What's New
2021（January－June）
-
2021.6.25
-
2021.6.10
-
2021.6.10
-
2021.6.9
-
2021.6.9
-
2021.6.8
-
2021.5.28
-
2021.5.23
-
2021.5.19
-
2021.5.12
-
2021.5.12
-
2021.5.9
-
2021.5.5
-
2021.4.23
-
2021.4.20
-
2021.4.17
-
2021.4.16
-
2021.4.14
-
2021.4.14
-
2021.4.1
-
2021.3.31
-
2021.3.23
-
2021.3.16
-
2021.3.16
-
2021.3.14
-
2021.3.9
-
2021.2.22
-
2021.2.22
-
2021.2.21
-
2021.2.17
-
2021.2.14
-
2021.2.6
-
2021.2.5
-
2021.2.1
-
2021.1.20
-
2021.1.19
-
2021.1.18
-
2021.1.13
-
2021.1.5
-
2021.6.25
A paper on the antimicrobial effect of Ti alloy using Cu was published in Materials Transactions.
Qiang Li, Jinshuai Yang, Junjie Li, Ran Zhang, Masaaki Nakai, Mitsuo Niinomi, Takayoshi Nakano:
Antibacterial Cu-doped calcium phosphate coating on pure titanium,
Materials Transactions, 62 [7], (2021), 1052-1055.
http://doi.org/10.2320/matertrans.MT-M2021005Click here for this paper.
Abstract
Cu-doped amorphous calcium phosphate (ACP) coatings were fabricated on the surface of pure titanium (Ti) by electrochemical deposition at initial electrolyte temperatures of 35, 45, and 55 °C. The antibacterial activities of the coatings were then evaluated by the plate counting method using Escherichia coli as the indicator. The Cu concentrations on the surfaces of samples are increased from 6.90 to 15.05 mass% as initial electrolyte temperature is increased from 35 to 55 °C. The Cu-doped ACP coatings show that they can fully inhibit the growth of E. coli.
-
2021.6.10
A study on the peculiar microstructure and mechanical study of γ-TiAl intermetallic compound with β-phase formed by electron beam metal 3D printing has been published in Additive Manufacturing in open access.
Ken Cho, Hajime Kawabata, Tatsuhiro Hayashi, Hiroyuki Y. Yasuda*, Hirotoyo Nakashima, Masao Takeyama, Takayoshi Nakano:
Peculiar microstructural evolution and tensile properties of β-containing γ-TiAl alloys fabricated by electron beam melting,
Additive Manufacturing, (2021), 102091.
https://doi.org/10.1016/j.addma.2021.102091Click here for this paper.
ABSTRACT
The microstructure and tensile properties of β-containing Ti-44Al-4Cr alloy rods additively manufactured by electron beam melting (EBM) process were examined as a function of input energy density determined by the processing parameters. To the best of our knowledge, this is the first report to demonstrate that two types of fine microstructures have been obtained in the β-containing γ-TiAl alloys by varying the energy density during the EBM process. A uniform α2/β/γ mixed structure containing an α2/γ lamellar region and a β/γ dual-phase region is formed at high energy density conditions. On the other hand, a lower energy density leads to the formation of a peculiar layered microstructure perpendicular to the building direction, consisting of a ultrafine α2/γ lamellar grain layer and a α2/β/γ mixed structure layer. The difference in the microstructures originates from the difference in the solidification microstructure and the temperature distribution from the melt pool, which are dependent on the energy density. Furthermore, it was found that the strength of the alloys is closely related to the volume fractions of the β phase and the ultrafine α2/γ lamellar grains which originates from the massive α grains formed by rapid cooling under low energy density conditions. The alloys with high amounts of these peculiar microstructures exhibit high strength comparable to and higher than the conventional β-containing γ-TiAl at room temperature and 1023 K, respectively. -
2021.6.10
A study on the peculiar microstructure and mechanical study of γ-TiAl intermetallic compound with β-phase formed by electron beam metal 3D printing has been published in Additive Manufacturing in open access.
Ken Cho, Hajime Kawabata, Tatsuhiro Hayashi, Hiroyuki Y. Yasuda*, Hirotoyo Nakashima, Masao Takeyama, Takayoshi Nakano:
Peculiar microstructural evolution and tensile properties of β-containing γ-TiAl alloys fabricated by electron beam melting,
Additive Manufacturing, 46, (2021), 102091; 1-12.
https://doi.org/10.1016/j.addma.2021.102091Click here for this paper.
ABSTRACT
The microstructure and tensile properties of β-containing Ti-44Al-4Cr alloy rods additively manufactured by electron beam melting (EBM) process were examined as a function of input energy density determined by the processing parameters. To the best of our knowledge, this is the first report to demonstrate that two types of fine microstructures have been obtained in the β-containing γ-TiAl alloys by varying the energy density during the EBM process. A uniform α2/β/γ mixed structure containing an α2/γ lamellar region and a β/γ dual-phase region is formed at high energy density conditions. On the other hand, a lower energy density leads to the formation of a peculiar layered microstructure perpendicular to the building direction, consisting of a ultrafine α2/γ lamellar grain layer and a α2/β/γ mixed structure layer. The difference in the microstructures originates from the difference in the solidification microstructure and the temperature distribution from the melt pool, which are dependent on the energy density. Furthermore, it was found that the strength of the alloys is closely related to the volume fractions of the β phase and the ultrafine α2/γ lamellar grains which originates from the massive α grains formed by rapid cooling under low energy density conditions. The alloys with high amounts of these peculiar microstructures exhibit high strength comparable to and higher than the conventional β-containing γ-TiAl at room temperature and 1023 K, respectively. -
2021.6.9
A paper reported the phenomenon that the orientation of human iPSC-osteoblasts is strongly oriented through the adhesion group by an oriented collagen scaffold material has been published in the International Journal of Molecular Sciences as an openaccess
Ryosuke Ozasa#, Aira Matsugaki#, Tadaaki Matsuzaka, Takuya Ishimoto, Yun Hui-suk, Takayoshi Nakano*:
Superior alignment of human iPSC-osteoblasts associated with focal adhesion formation stimulated by oriented collagen scaffold,
International Journal of Molecular Sciences, 22, (2021), 6232; 1-11.
https://doi.org/10.3390/ijms22126232
#These authors contributed equally to this work.
*Corresponding authorClick here for this paper.
Abstract:
Human-induced pluripotent stem cells (hiPSCs) can be applied in patient-specific cell therapy to regenerate lost tissue or organ function. Anisotropic control of the structural organization in the newly generated bone matrix is pivotal for functional reconstruction during bone tissue regeneration. Recently, we revealed that hiPSC-derived osteoblasts (hiPSC-Obs) exhibit preferential alignment and organize in highly ordered bone matrices along a bone-mimetic collagen scaffold, indicating their critical role in regulating the unidirectional cellular arrangement, as well as the structural organization of regenerated bone tissue. However, it remains unclear how hiPSCs exhibit the cell properties required for oriented tissue construction. The present study aimed to characterize the properties of hiPSCs-Obs and those of their focal adhesions (FAs), which mediate the structural relationship between cells and the matrix. Our in vitro anisotropic cell culture system revealed the superior adhesion behavior of hiPSC-Obs, which exhibited accelerated cell proliferation and better cell alignment along the collagen axis compared to normal human osteoblasts. Notably, the oriented collagen scaffold stimulated FA formation along the scaffold collagen orientation. This is the first report of the superior cell adhesion behavior of hiPSC-Obs associated with the promotion of FA assembly along an anisotropic scaffold. These findings suggest a promising role for hiPSCs in enabling anisotropic bone microstructural regeneration. -
2021.6.9
The winners of the Japan Institute of Metals Fall Awards were unofficially announced, and Nakano Lab received three awards.
〇Aira Matsugaki et al: The 18th Murakami Encouragement Award,
The Japan Institute of Metals and Materials, September 14, 2021〇Taketsugu Nagase, Mitsuhiro Toshiro, Takayoshi Nakano: 69th Best Paper Award, Development of Co-Cr-Mo-Fe-Mn-W and Co-Cr-Mo-Fe
For : Development of Co-Cr-Mo-Fe-Mn-W and Co-Cr-Mo-Fe-Mn-W-Ag High-Entropy Alloys Based on Co-Cr-Mo Alloys.
The Japan Institute of Metals and Materials, September 14, 2021〇Aira Matsugaki and T. Nakano: The 11th Matelia Award, for the
For : Induction of Bone Functionalization Based on the Mechanism of Cell and Bone Matrix Orientation
The Japan Institute of Metals and Materials, September 14, 2021 -
2021.6.8
A paper on antibacterial properties and osteoblast adhesion of Ag-doped defective apatite was published as open access in Crystals (MDPI).
Ozkan Gokcekaya, Celaletdin Ergun*, Thomas J. Webster, Abdurrahman Bahadir, Kyosuke Ueda, Takayuki Narushima, Takayoshi Nakano:
Effect of precursor deficiency induced Ca/P ratio on antibacterial and osteoblast adhesion properties of Ag-incorporated hydroxyapatite: Reducing Ag toxicity,
Materials, 14, (2021), 3158; 1-18.
https://doi.org/10.3390/ma14123158
*: Corresponding authorClick here for this paper.
Abstract: Ag-containing hydroxyapatite (HA) can reduce risks associated with bacterial infections which may eventually require additional surgical operations to retrieve a failed implant. The biological properties of HA in such applications are strongly affected by its composition in terms of dopants as well as Ca/P stoichiometry, which can be easily controlled by altering processing parameters, such as precursor concentrations. The objective of this in vitro study was to understand the effect of variations in HA precursor solutions on antibacterial properties against Escherichia coli (E. coli) and for promoting osteoblast (bone-forming cell) adhesion on Ag incorporated HA (AgHA) which has not yet been investigated. For this, two groups of AgHAs were synthesized via a precipitation method by adjusting precursor reactants with a stoichiometric value of 1.67, being either (Ca + Ag)/P (Ca-deficient) or Ca/(P + Ag) (P-deficient), and were characterized by XRD, FTIR, and SEM1EDS. Results showed that Ag+ incorporated into the Ca2+ sites was associated with a corresponding OH− vacancy. Additional incorporation of CO32− into PO43− sites occurred specifically for the P-deficient AgHAs. While antibacterial properties increased, osteoblast adhesion decreased with increasing Ag content for the Ca-deficient AgHAs, as anticipated. In contrast, significant antibacterial properties with good osteoblast behavior were observed on the P-deficient AgHAs even with a lower Ag content, owing to carbonated HA. Thus, this showed that by synthesizing AgHA using P-deficient precursors with carbonate substitution, one can keep the antibacterial properties of Ag in HA while reducing its toxic effect on osteoblasts.
-
2021.5.28
The journal Additive Manufacturing (Elsevier) has published an open access paper showing that the improvement in corrosion resistance of stainless steel (SUS316L) by metal 3D printing is not affected by microstructure and the associated dislocation densit
Yusuke Tsutumi*, Takuya Ishimoto, Tastuya Oishi, Tomoyo Manaka, Peng Chen, Maki Ashida, Kotaro Doi, Hideki Katayama, Takao Hanawa, Takayoshi Nakano*:
Crystallographic texture- and grain boundary density-independent improvement of corrosion resistance in austenitic 316L stainless steel fabricated via laser powder bed fusion,
Additive manufacturing, (2021), 102066; 1-9.
https://doi.org/10.1016/j.addma.2021.102066
*: Corresponding authorClick here for this paper.
Abstract
Improvement of corrosion resistance of austenitic 316 L 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 the corrosion resistance of LPBF-fabricated parts have not been elucidated. For biomedical applications, crystallographic texture control from a single crystalline-like to randomly oriented polycrystalline microstructure is highly attractive for optimizing the mechanical properties (particularly the Young’s modulus) of implants. An investigation of the impacts of crystallographic planes and grain boundaries exposed to the biological environment on corrosion behavior is necessary. 316 L stainless steels with different crystallographic textures and grain boundary densities were successfully fabricated via LPBF. The corrosion resistances of the LPBF-fabricated specimens were comprehensively assessed by anodic polarization, dissolution, and crevice corrosion repassivation tests. The LPBF-fabricated specimens showed extremely high pitting potentials in the physiological saline compared with the commercially available counterparts, and importantly, excellent pitting corrosion resistance was observed irrespective of the crystallographic planes and grain boundary density exposed. Moreover, the LPBF-fabricated specimens did not show metastable pitting corrosion even in an accelerated test using an acid solution. The repassivation behavior of the specimens was not affected by LPBF. Such a drastic improvement in the corrosion resistances of the LPBF-fabricated specimens might be attributed to suppression of inclusion coarsening owing to the rapid cooling rate during solidification in LPBF. By using LPBF, the desired crystallographic texture can be introduced based on the desired mechanical properties without concern for corrosiveness. -
2021.5.23
The results of a joint research with Professor Mikako Hayashi at Osaka University Graduate School of Dentistry have been published as an open access article in Dental Materials Journal.
Kyoko Yagi, Reo Uemura, Hiroko Yamamoto, Takuya Ishimoto, Katsuaki Naito, Shousaku Itoh, Yasuhiro Matsuda, Katsushi Okuyama, Takayoshi Nakano, Mikako Hayashi:
In-air micro-proton-induced X-ray/gamma-ray emission analysis of the acid resistance of root dentin after applying fluoride-containing materials incorporating calcium,
Dental Materials Journal, (2021), online.
https://doi.org/10.4012/dmj.2020-273Click here for this paper.
Click here for this PDF.Abstract
This study employed an in-air micro-proton-induced X-ray/gamma-ray emission system to assess the effectiveness of fluoride-containing materials (FCMs) incorporating calcium in preventing root caries. Dentin surfaces of human third molars were coated with one of three FCMs: fluoride-releasing glass-ionomer cement (F7) and experimental materials in which half (P1) or all (P2) of the strontium in F7 was replaced with calcium. Dentin without FCM coating served as the control. Specimens were immersed in saline at 37°C for 1 month, sectioned, and then demineralized. Calcium loss after demineralization was lower in the Ca-substituted groups than in the Ca-unsubstituted groups (p<0.05). Calcium loss was negatively correlated with fluoride uptake (p<0.01). In the F7, P1, and P2 groups, the retraction of the dentin surface was significantly suppressed as compared with the control group. FCMs incorporating calcium improved the acid resistance of root dentin and could help prevent root caries. -
2021.5.19
A paper quantitatively demonstrating that the shape and arrangement of osteocyte lacunae are determinants of bone orientation has been published as an open access article in Calcified Tissue International. This is a joint research with Prof. Ueoka of Okay
Takuya Ishimoto, Keita Kawahara, Aira Matsugaki, Hiroshi Kamioka, Takayoshi Nakano*:
Quantitative Evaluation of Osteocyte Morphology and Bone Anisotropic Extracellular Matrix in Rat Femur,
Calcified Tissue International, (2021), online.
https://doi.org/10.1007/s00223-021-00852-1Click here for this paper
Click here for PDFAbstract
Osteocytes are believed to play a crucial role in mechanosensation and mechanotransduction which are important for maintenance of mechanical integrity of bone. Recent investigations have revealed that the preferential orientation of bone extracellular matrix (ECM) mainly composed of collagen fibers and apatite crystallites is one of the important determinants of bone mechanical integrity. However, the relationship between osteocytes and ECM orientation remains unclear. In this study, the association between ECM orientation and anisotropy in the osteocyte lacuno-canalicular system, which is thought to be optimized along with the mechanical stimuli, was investigated using male rat femur. The degree of ECM orientation along the femur longitudinal axis was significantly and positively correlated with the anisotropic features of the osteocyte lacunae and canaliculi. At the femur middiaphysis, there are the osteocytes with lacunae that highly aligned along the bone long axis (principal stress direction) and canaliculi that preferentially extended perpendicular to the bone long axis, and the highest degree of apatite c-axis orientation along the bone long axis was shown. Based on these data, we propose a model in which osteocytes can change their lacuno-canalicular architecture depending on the mechanical environment so that they can become more susceptible to mechanical stim -
2021.5.12
Acta Materialia has published an open access article on unique tissues freely formed with Inconel718 by laser metal 3D printing.
Ozkan Gokcekaya#, Takuya Ishimoto#, Shinya Hibino, Jumpei Yasutomi, Takayuki Narushima, Takayoshi Nakano*:
Unique crystallographic texture formation in Inconel 718 by laser powder bed fusion and its effect on mechanical anisotropy,
Acta Materialia, 212, (2021), 116876; 1-12..
https://doi.org/10.1016/j.actamat.2021.116876
#: The authors equally contribute to this article.Click here for this paper.
Abstract
Additive manufacturing offers an exclusive way of anisotropic microstructure control with a high degree of freedom regarding variation in process parameters. This study demonstrates a unique texture formation in Inconel 718 (IN718) using a bidirectional laser scan in a laser powder bed fusion (LPBF) process for tailoring the mechanical properties. We developed three distinctive textures in IN718 using LPBF: a single-crystal-like microstructure (SCM) with a <110> orientation in the build direction (BD), crystallographic lamellar microstructure (CLM) with a <110>-oriented main layer and <100>-oriented sub-layer in the BD, and polycrystalline with a weak orientation. The microstructure observations and finite element simulations showed that the texture evolution of the SCM and CLM was dominated by the melt-pool shape and related heat-flow direction. The specimen with CLM exhibited a simultaneous improvement in strength and ductility owing to the stress-transfer coefficient between the <110>-oriented main and <100>-oriented sub-grains, showing superior mechanical properties compared to cast-IN718. This behavior is largely attributed to the presence of the boundary between the main and sub-layers (crystallographic grain boundary) lying parallel to the BD uniquely formed under the LPBF process. Furthermore, the strength–ductility balance of the part with the CLM can be controlled by changing the stress-transfer coefficient and the Schmidt factor through an alteration of the loading axis. Control of the crystallographic texture, including the CLM formation, is beneficial for tailoring and improving the mechanical performance of the structural materials, which can be a promising methodology
Keywords
Laser powder bed fusion, Inconel 718, Crystallographic texture, Lamellae, Mechanical anisotropy -
2021.5.12
Our research on the mechanism and stability of crystallographic orientation relationships formed by metal AM, as well as the possibility of seeding single crystals, has been published as an open access paper in Additive Manufacturing.
Takuya Ishimotoǂ, Koji Hagiharaǂ, Kenta Hisamoto, Takayoshi Nakano*:
Stability of crystallographic texture in laser powder bed fusion: Understanding the competition of crystal growth using a single crystalline seed,
Additive Manufacturing, 43, (2021), 102004; 1-11.
https://doi.org/10.1016/j.addma.2021.102004
ǂ These authors contributed equally to this work.Click here for this paper.
Abstract
In metal additive manufacturing, crystallographic orientation control is a promising method for tailoring the functions of metallic parts. However, despite its importance in the fabrication of texture-controlled functional parts, the stability of the crystallographic texture is not widely discussed. Herein, the crystallographic texture stability under laser powder bed fusion was investigated. Two methodologies were employed. One is that a laser scanning strategy was alternately changed for a specific number of layers. The other is a “seeding” experiment in which single-crystalline substrates with controlled crystallographic orientations in the building (z-) direction and the xy-plane (perpendicular to the building direction) were used as the starting substrate. The transient zone width, where the crystallographic orientation was inherited from the layer beneath, was analyzed to evaluate the texture stability. The crystallographic direction of the seed within the xy-plane, rather than the building direction, determined the transient zone width, i.e., the texture stability. In particular, the texture in the newly deposited portion was stable when the laser scanning direction matched the <100> orientation in the underneath layer, otherwise the crystal orientation switched rapidly, such that the <100> orientation was parallel to the scanning direction. Interestingly, the crystallographic orientation along the building direction in the underneath layer hardly impacted the stability of the texture. Therefore, for the first time, it has been clarified that the <100> orientation in the scanning direction, rather than the building direction, was preferentially stabilized, whereas the orientation in the other directions secondary stabilized. -
2021.5.9
Our paper on the discovery of lattice deformation due to residual strain in AM-formed β-type titanium alloy has been published as an open access paper in Scripta Materialia.
Aya Takase*, Takuya Ishimoto, Ryoya Suganuma, Takayoshi Nakano*:
Lattice distortion in selective laser melting (SLM)-manufactured unstable β-type Ti-15Mo-5Zr-3Al alloy analyzed by high-precision X-ray diffractometry,
Scripta Materialia, 201, (2021), 113953; 1-6.
https://doi.org/10.1016/j.scriptamat.2021.113953Abstract
A peculiar lattice distortion in a selective laser melting (SLM)-manufactured unstable β-type Ti-15Mo-5Zr-3Al was observed for the first time, through high-precision X-ray diffraction (XRD) analyses. After SLM, Ti-15Mo-5Zr-3Al exhibited a body-centered-tetragonal structure instead of a body-centered-cubic structure; the c-axis was 0.63% shorter than the a-axis. The XRD analyses also revealed tensile residual stresses of 210 ± 12 MPa at the specimen surface. A numerical simulation indicated rapid cooling during the SLM, which could have caused the residual stresses. A comparison of the partially stress-released SLM specimen and an electron beam melting-manufactured specimen with negligible residual stress suggested that the residual stress caused by the rapid cooling in SLM induced the lattice distortion. This finding is not consistent with the previous understanding that residual stress changes the lattice parameter without lattice distortion. This study provides new insight into lattice distortion generated by a combination of SLM-specific ultrarapid cooling and unstable phases.Click here for this paper.
-
2021.5.5
A joint research paper with Keio University School of Medicine and others on the discovery of auditory osteoblasts and their functionalization through bone density and apatite orientation was published as an open access paper in Journal of Bone and Minera
Yukiko Kuroda, Katsuhiro Kawaai, Naoya Hatano, Yanlin Wu, Hidekazu Takano, Atsushi Momose, Takuya Ishimoto, Takayoshi Nakano, Paul Roschger, Stéphane Blouin, Koichi Matsuo*:
Hypermineralization of hearing-related bones by a specific osteoblast subtype,
Journal of Bone and Mineral Research, (2021)
https://doi.org/10.1002/jbmr.4320Click here for this paper.
Abstract
Auditory ossicles in the middle ear and bony labyrinth of the inner ear are highly mineralized in adult mammals. Cellular mechanisms underlying formation of dense bone during development are unknown. Here, we found that osteoblast‐like cells synthesizing highly mineralized hearing‐related bones produce both type I and type II collagens as the bone matrix, while conventional osteoblasts and chondrocytes primarily produce type I and type II collagens, respectively. Furthermore, these osteoblast‐like cells were not labeled in a “conventional osteoblast”‐specific green fluorescent protein (GFP) mouse line. Type II collagen‐producing osteoblast‐like cells were not chondrocytes as they express osteocalcin, localize along alizarin‐labeled osteoid, and form osteocyte lacunae and canaliculi, as do conventional osteoblasts. Auditory ossicles and the bony labyrinth exhibit not only higher bone matrix mineralization but a higher degree of apatite orientation than do long bones. Therefore, we conclude that these type II collagen‐producing hypermineralizing osteoblasts (termed here auditory osteoblasts) represent a new osteoblast subtype. -
2021.4.23
Dr. Nakano has been appointed as the 70th President of the Japan Institute of Metals and Materials. His term of office is for two years.
Dr. Nakano has been appointed as the 70th President of the Japan Institute of Metals and Materials. His term of office is for two years.
-
2021.4.20
Our paper on the discovery of lattice deformation due to residual strain in AM-formed β-titanium alloys has been accepted by Scripta Materialia. The paper will be published as an open access article.
Aya Takase*, Takuya Ishimoto, Ryoya Suganuma, Takayoshi Nakano*:
Lattice distortion in selective laser melting (SLM)-manufactured unstable β-type Ti-15Mo-5Zr-3Al alloy analyzed by high-precision X-ray diffractometry,
Scripta Materialia, (2021), in press. -
2021.4.17
In collaboration with Tokyo Dental University, our paper on botulinum-induced changes in bone quality was published in the Journal of Hard Tissue Biology as open access.
Gaku Kusaba, Satoru Matsunaga, Kei Kitamura, Masaaki Kasahara, Yoshiaki Shimoo, Shinichi Abe, Takayoshi Nakano, Takuya Ishimoto, Atsuhiko Hikita, Kunihiko Nojima, Yasushi Nishii:
Micro/nanostructural Characteristic Changes in the Mandibles of Rats after Injection of Botulinum Neurotoxin, Journal of Hard Tissue Biology, 30(2), (2021), 183-192.
DOI: 10.2485/jhtb.30.183Click here for this paper.
Click here for this PDF.Abstract
Our objective was to perform a quantitative evaluation of changes in the micro/nanostructural characteristics of entheses in rats with reduced masticatory muscle functional pressure, with the aim of elucidating the mechanism whereby masticatory muscle functional pressure contributes to growth and development of the mandible from a biomechanical perspective. Male Wister rats aged 4, 11, 18 and 25 weeks were divided into a Botox group injected with a botulinum toxin serotype A formulation to reduce muscle function (BTX) and a control group (CTRL). They were euthanized 6 weeks later and bone quality at the masseter insertion at the mandibular was analyzed. In the BTX group, the number of fibrous chondrocytes at entheses was significantly lower than in the CTRL group at all ages. The diameter of collagen fiber bundles in rats in the BTX group injected with BoNT/A during their growth phase was significantly smaller than that of rats in the CTRL group. In the mandibles of rats in the CTRL group the preferential alignment was consistent with the orientations of the muscle and tendon, but in growing rats treated with BTX, it was less closely aligned with the orientations of the muscle and tendon. -
2021.4.16
A paper on tissue control simulation in AM was published as open access in Materials Transactions.
Jun Kubo, Yuichiro Koizumi, Takuya Ishimoto and Takayoshi Nakano:
Modified Cellular Automaton Simulation of Metal Additive Manufacturing,
Materials Transactions, (2021) 103–109.Click here for this paper
Abstract
Metal additive manufacturing (AM) technologies are attracting attentions not only as a fabrication process of complicated three-dimensional parts but also as microstructure controlling processes. In powder bed fusion (PBF)-type AM, crystallographic texture can be controlled by scanning strategies of energy beam. To optimize microstructures, computer simulations for predicting microstructures play very important roles. In this work, we have developed simulation programs to explain the mechanism of the crystal orientation control. First, we simulated the shape of melt pool by analyzing the heat transfer using apparent heat conductivity when the penetration of laser beam through keyholes was taken into consideration because of the evaporation and accompanying convections. It was assumed that the primary crystal growth direction can be determined by the temperature gradient, and the crystals grow keeping the growth direction as generally recognized. The shapes of simulated melt pools agree well with experimental observations. The modified cellular automaton simulations successfully reproduced two typical textures with different preferential orientations along the building directions of 〈100〉 and 〈110〉 when the bidirectional scanning with and without a rotation of 90°, respectively, was accomplished between the layers. -
2021.4.14
A new mechanism for the strengthening of LPSO layers by Mg alloys has been published in Acta Materialia as an open access article.
Koji Hagihara*, Ryohei Ueyama, Michiaki Yamasaki, Yoshihito Kawamura, Takayoshi Nakano:
Surprising increase in yield stress of Mg single crystal using long-period stacking ordered nanoplates,
Acta Materialia, (2021), 116797.
https://doi.org/10.1016/j.actamat.2021.116797Click here for this paper.
Click here for this PDF.Abstract
Mg–Zn–Y ternary alloys containing the long-period stacking ordered (LPSO) phase exhibit superior mechanical properties. This is believed to be originating from the LPSO phase acting as the strengthening phase. However, we first clarify that the mechanical properties of the matrix Mg solid solution in the Mg/LPSO two-phase alloy are significantly different from those of pure Mg. The yield stress of a Mg99.2Zn0.2Y0.6 single crystal (matrix Mg solid solution) is almost the same as that of an LPSO single-phase alloy. This is ascribed to the formation of thin stacking-fault-like defects, named “LPSO nanoplate”. In Mg99.2Zn0.2Y0.6, kink-band formation is induced in the same manner as that in the LPSO phase in deformation, resulting in high strength accompanied with increased ductility. Our results suggest that the strengthening mechanism of the Mg/LPSO two-phase alloy must be reconsidered depending on the microstructure. Furthermore, the results suggest that new ultrahigh-strength Mg alloys, which have much lower Zn and Y contents but the mechanical properties are comparable or superior than the present Mg/LPSO two-phase alloys, are expected to be developed via the appropriate control of LPSO nanoplate microstructures. -
2021.4.14
A study on the mechanism of improved wear properties of biological Co-Cr-Mo alloy single crystals was published as an open access paper in Wear magazine (Elsevier).
Takayoshi Nakano*, Koji Hagihara, Ana R. Ribeiro, Yusuke Fujiia, Tsubasa Todo, Ryo Fukushima, Luís Augusto Rocha:Orientation dependence of the wear resistance in the Co–Cr–Mo single crystal, Wear 478–479 (2021) 203758.
https://doi.org/10.1016/j.wear.2021.203758Click here for this paper.
Click here for this PDF.
Abstract
This is the report clarifying the orientation dependence of the wear behavior of Co–Cr–Mo alloy. The wear resistance of the Co–Cr–Mo alloy with face-centered cubic (fcc) structure was found to be higher on the planes in order of {110}, {001} and {111}. Quantitatively, the wear resistance on {110} is 1.5 times larger than that on {111}. The tendency showed in coincident with the orientation dependence of the surface hardness, as empirically suggested. However, we additionally found in the observation of the worn surface in the fcc-single crystals that the volume fraction of the hexagonal close-packed (hcp)-phase, which was formed as the strain-induced martensite during the wear test, was larger in the same order of the wear resistance. The variation in formation frequency of the hcp-phase during the wear test can be explained by focusing on the Schmid factor along the resultant direction of the applied stress and the friction stress. On the {111} surface where the Schmid factor for the strain-induced ε-martensite formation is small, homogeneous deformation microstructure covered by it was not developed even after long-time wear, resulting in lower wear resistance. The results strongly suggest that not only the hardness, but the distribution of the ε-martensite is important to control the wear behavior of the Co–Cr alloys with the extremely low stacking fault energy, and it can be achieved by the crystal orientation control in the γ-phase. -
2021.4.1
Our paper on CaO-SrO-P2O5-TiO2 bioglass has been published as an open access article in Materials (MDPI).
Sungho Lee*, Fukue Nagata, Katsuya Kato, Takayoshi Nakano, Toshihiro Kasuga:
Structures and dissolution behaviors of quaternary CaO-SrO-P2O5-TiO2 glasses,
Materials, 14 [7], (2021), 1736; 1-13.
https://doi.org/10.3390/ma14071736Click here for this paper.
Click here for this PDF.Abstract
Calcium phosphate glasses have a high potential for use as biomaterials because their composition is similar to that of the mineral phase of bone. Phosphate glasses can dissolve completely in aqueous solution and can contain various elements owing to their acidity. Thus, the glass can be a candidate for therapeutic ion carriers. Recently, we focused on the effect of strontium ions for bone formation, which exhibited dual effects of stimulating bone formation and inhibiting bone resorption. However, large amounts of strontium ions may induce a cytotoxic effect, and there is a need to control their releasing amount. This work reports fundamental data for designing quaternary CaO-SrO-P2O5-TiO2 glasses with pyro- and meta-phosphate compositions to control strontium ion-releasing behavior. The glasses were prepared by substituting CaO by SrO using the melt-quenching method. The SrO/CaO mixed composition exhibited a mixed cation effect on the glassification degree and ion-releasing behavior, which showed non-linear properties with mixed cation compositions of the glasses. Sr2+ ions have smaller field strength than Ca2+ ions, and the glass network structure may be weakened by the substitution of CaO by SrO. However, glassification degree and chemical durability of pyro- and meta-phosphate glasses increased with substituted all CaO by SrO. This is because titanium groups in the glasses are closely related to their glass network structure by SrO substitution. The P-O-Ti bonds in pyrophosphate glass series and TiO4 tetrahedra in metaphosphate glass series increased with substitution by SrO. The titanium groups in the glasses were crosslink and/or coordinate phosphate groups to improve glassification degree and chemical durability. Sr2+ ion releasing amount of pyrophosphate glasses with >83% SrO substitution was larger than 0.1 mM at day seven, an amount that reported enhanced bone formation by stimulation of osteogenic markers.Keywords: bioactive glass; phosphate glass; structure; dissolution behavior; strontium
-
2021.3.31
Nakano Lab's paper has been published in the Journal of Japanese Society For Bone Morphometry as an open access journal.
T. Matsuzaka, A. Matsugaki, and T. Nakano:
Construction of an anisotropic co-culture model under stress loading to elucidate the mechanism of micro-orientation structure formation in bone,
Journal of the Japanese Society For Bone Morphometry, (2021), 31, 45-51.Click here for this article.
-
2021.3.23
Dr. Nakano was informally selected to receive JSPM Award for Distinguished Achievements in Research from Japan Society of Powder and Powder Metallurgy on June 3, 2021.
Takayoshi Nakano:
Research and Development on Anisotropic Microstructure Control Based on Powder Metallurgy including Three-Dimensional Laminated Metal Fabrication,
JSPM Award for Distinguished Achievements in Research, June 3, 2021, Japan Society of Powder and Powder Metallurgy -
2021.3.16
Dr. Matsugaki will receive the Research Encouragement Award of the Biomedical Materials Division, The Society of Materials Sciences, Japan, 2020.
Aira Matsugaki:
Elucidation of the Biological Mechanism of Bone Functionalization and Development of Bone Orientation Inducing Materials Based on the Mechanism,
The Society of Materials Sciences, Japan, the Research Encouragement Award of the Biomedical Materials Division, 2020. -
2021.3.16
Dr. Nakano was awarded The 27th Japan Institute of Metals and Materials Masumoto Hakaru Award.
Takayoshi Nakano:
Elucidation of the Mechanism of Bone Microstructure Orientation as a Functional Material and Research on Bone Metal Implants Based on the Mechanism,
The 27th Japan Institute of Metals and Materials Masumoto Hakaru Award, March 16, 2021, The Japan Institute of Metals and Materials.
-
2021.3.14
A new mechanism for the strengthening of LPSO layers by Mg alloys has been published in Acta Materialia as an open access article.
Koji Hagihara*, Ryohei Ueyama, Michiaki Yamasaki, Yoshihito Kawamura, Takayoshi Nakano:
Surprising increase in yield stress of Mg single crystal using long-period stacking ordered nanoplates,
Acta Materialia, (2021), 116797.
https://doi.org/10.1016/j.actamat.2021.116797Click here dor this paper.
Click here for this PDF.Abstract
Mg–Zn–Y ternary alloys containing the long-period stacking ordered (LPSO) phase exhibit superior mechanical properties. This is believed to be originating from the LPSO phase acting as the strengthening phase. However, we first clarify that the mechanical properties of the matrix Mg solid solution in the Mg/LPSO two-phase alloy are significantly different from those of pure Mg. The yield stress of a Mg99.2Zn0.2Y0.6 single crystal (matrix Mg solid solution) is almost the same as that of an LPSO single-phase alloy. This is ascribed to the formation of thin stacking-fault-like defects, named “LPSO nanoplate”. In Mg99.2Zn0.2Y0.6, kink-band formation is induced in the same manner as that in the LPSO phase in deformation, resulting in high strength accompanied with increased ductility. Our results suggest that the strengthening mechanism of the Mg/LPSO two-phase alloy must be reconsidered depending on the microstructure. Furthermore, the results suggest that new ultrahigh-strength Mg alloys, which have much lower Zn and Y contents but the mechanical properties are comparable or superior than the present Mg/LPSO two-phase alloys, are expected to be developed via the appropriate control of LPSO nanoplate microstructures. -
2021.3.9
Our paper has been published in The Journal of The Society of Inorganic Materials in Open Access.
Seong-Ho Lee, Okue Nagata, Katsuya Kato, Takayoshi Nakano, Toshihiro Kasuga:
Improving chemical durability of calcium phosphate invert glasses by Al2O3 addition,
The Journal of The Society of Inorganic Materials, (2021), 28, 67-73.Click here for this PDF.
-
2021.2.22
The results of a collaorate research project with the Department of Orthopaedic Surgery, Osaka University on bone control using magnetic fields have been published in the journal "Bone Reports" as open access.
Rintaro Okada, Kai Yamato, Minoru Kawakami, Joe Kodama, Junichi Kushioka, Daisuke Tateiwa , Yuichiro Ukon , Bal Zeynep, Takuya Ishimoto, Takayoshi Nakano, Hideki Yoshikawa, Takashi Kaito＊:
Low magnetic field promotes recombinant human BMP-2-induced bone formation and influences orientation of trabeculae and bone marrow-derived stromal cells,
Bone Reports, (2021), 100757; 1-.
https://doi.org/10.1016/j.bonr.2021.100757Click here for this paper.
Click here for this PDF.Abstract
Effects of high magnetic fields [MFs, ≥ 1 T (T)] on osteoblastic differentiation and the orientation of cells or matrix proteins have been reported. However, the effect of low MFs (< 1 T) on the orientation of bone formation is not well known. This study was performed to verify the effects of low MFs on osteoblastic differentiation, bone formation, and orientation of both cells and newly formed bone. An apparatus was prepared with two magnets (190 mT) aligned in parallel to generate a parallel MF. In vitro, bone marrow-derived stromal cells of rats were used to assess the effects of low MFs on cell orientation, osteoblastic differentiation, and mineralization. A bone morphogenetic protein (BMP)-2-induced ectopic bone model was used to elucidate the effect of low MFs on microstructural indices, trabecula orientation, and the apatite c-axis orientation of newly formed bone. Low MFs resulted in an increased ratio of cells oriented perpendicular to the direction of the MF and promoted osteoblastic differentiation in vitro. Moreover, in vivo analysis demonstrated that low MFs promoted bone formation and changed the orientation of trabeculae and apatite crystal in a direction perpendicular to the MF. These changes led to an increase in the mechanical strength of rhBMP-2-induced bone. These results suggest that the application of low MFs has potential to facilitate the regeneration of bone with sufficient mechanical strength by controlling the orientation of newly formed bone. -
2021.2.22
Our laboratory's commentary was published in Precision Medicine's "Utilization of Personal Health Records" (March issue).
Aira Matsugaki, Takuya Ishimoto, Ryosuke Ozasa, Naoko Ikeo, Takayoshi Nakano:
Evaluation and control of bone collagen/apatite orientation for the realization of personal bone quality medicine,
Precision Medicine "Utilization of personal health record", Vol. 4, March, (2021),pp.59-68 (245-254).
Click here for this commentary.
Click here for this PDF. -
2021.2.21
Our laboratory's commentary will appear in the March issue of Precision Medicine's "Utilization of Personal Health Records".
Aira Matsugaki, Takuya Ishimoto, Ryosuke Kozasa, Naoko Igeo, and Takayoshi Nakano:
Evaluation of bone collagen/apatite orientation and its control for the realization of personal bone quality medicine,
Precision Medicine "Utilization of personal health record", March, (2021), in press. -
2021.2.17
The results of a collaborative study with the Department of Orthopaedic Surgery of Osaka University on bone control using magnetic fields have been accepted for publication in Bone Reports and will be open access.
Rintaro Okada, Kai Yamato, Minoru Kawakami, Joe Kodama, Junichi Kushioka, Daisuke Tateiwa , Yuichiro Ukon , Bal Zeynep, Takuya Ishimoto, Takayoshi Nakano, Hideki Yoshikawa, Takashi Kaito＊:
Low magnetic field promotes recombinant human BMP-2-induced bone formation and influences orientation of trabeculae and bone marrow-derived stromal cells,
Bone Reports, (2021), in press. -
2021.2.14
Our article on the early ossification process has been published in Tissue Engineering as an open access article.
Emilio Satoshi Hara, Masahiko Okada, Noriyuki Nagaoka, Takayoshi Nakano, Takuya Matsumoto*:
Re-evaluation of initial bone mineralization from an engineering perspective,
Tissue Engineering, Review Article-Part B, (2021), online.
https://doi.org/10.1089/ten.TEB.2020.0352Click here for this paper.
Click here for this PDF.Abstract
Bone regeneration was one of the earliest fields to develop in the context of tissue regeneration, and currently, repair of small-sized bone defects has reached a high success rate. Future researches are expected to incorporate more advanced techniques towards achieving rapid bone repair and modulation of the regenerated bone quality. For these purposes, it is important to have a more integrative understanding of the mechanisms of bone formation and maturation from multiple perspectives and to incorporate these new concepts into the development and designing of novel materials and techniques for bone regeneration. This review focuses on the analysis of the earliest stages of bone tissue development from the biology, material science, and engineering perspectives for a more integrative understanding of bone formation and maturation, and for the development of novel biology-based engineering approaches for tissue synthesis in vitro. More specifically, the authors describe the systematic methodology that allowed the understanding of the different nucleation sites in intramembranous and endochondral ossification, the space-making process for mineral formation and growth, as well as the process of apatite crystal cluster growth in vivo in the presence of suppressing biomolecules. -
2021.2.6
Mr. Ryo Fukushima (M1) was awarded the Best Presentation Award at The Iron and Steel Institute of Japan, The Japan Institute of Metals and Materials Kansai Branch, The 2nd Conference on Materials Science and Engineering (Student Conference) held on Februa
Ryo Fukushima:
Elucidation of the mechanism of bone mechanics control originating from trace metal elements,
Best Presentation Award, The Iron and Steel Institute of Japan and The Japan Institute of Metals and Materials Kansai Branch, (2021), Feb. 4, 2021 (WEB)
-
2021.2.5
A novel BioHEA capable of tensile deformation was successfully fabricated and published in Materials & Design as open access. It is expected to be developed into new practical applications.
Yuuka Iijima, Takeshi Nagase, Aira Matsugaki, Pan Wang, Kei Ameyama, Takayoshi Nakano*:
Design and development of Ti-Zr-Hf-Nb-Ta-Mo high-entropy Alloys for metallic biomaterials,
Materials & Design, (2021), in press.
https://doi.org/10.1016/j.matdes.2021.109548Click here for this paper.
Click here for this PDF.Abstract
Applying empirical alloy parameters (including Mo equivalent), the predicted ground state diagram, and thermodynamic calculations, noble nonequiatomic Ti–Zr–Hf–Nb–Ta–Mo high-entropy alloys for metallic biomaterials (BioHEAs) were designed and newly developed. It is found that the Moeq and valence electron concentration (VEC) parameters are useful for alloy design involving BCC structure formation in bio medium-entropy alloys and BioHEAs. Finally, we find a Ti28.33Zr28.33Hf28.33Nb6.74Ta6.74Mo1.55 (at.%) BioHEA that exhibits biocompatibility comparable to that of CP–Ti, higher mechanical strength than CP–Ti, and an appreciable room-temperature tensile ductility. The current findings pave the way for new Ti–Zr–Hf–Nb–Ta–Mo BioHEAs development and are applicable for another BioHEA alloys system. -
2021.2.1
Our paper on microstructure control to improve mechanical properties of Co-Cr-W-Ni for biomedical applications has been published in Materials Transactions.
Kosuke Ueki, Soh Yanagihara, Kyosuke Ueda, Masaaki Nakai, Takayoshi Nakano, Takayuki Narushima:
Improvement of Mechanical Properties by Microstructural Evolution of Biomedical Co-Cr-W-Ni Alloys with the Addition of Mn and Si,
Materials Transactions, 62 [2], (2021), 229-238.Click here for this paper.
Click here for this PDF.Abstract
We investigated changes in the microstructure and mechanical properties of biomedical Co-20Cr-15W-10Ni alloys (mass%) containing 8 mass% Mn and 0-3 mass% Si due to hot forging, solution treatment, cold swaging, and static recrystallization. The η-phase (M6X-M12X type cubic structure, M: metallic elements, X: C and/or N, space group: Fd-3m (227)) and CoWSi type Laves phase (C14 MgZn2 type hexagonal structure, space group: P63/mmc (194)) were confirmed as precipitates in the as-cast and as-forged alloys. To the best of our knowledge, this is the first report that reveals the formation of CoWSi type Laves phase precipitates in Co-Cr-W-Ni-based alloys. The addition of Si promoted the formation of precipitates of both η-phase and CoWSi type Laves phase. The solution-treated 8Mn+(0, 1)Si-added alloys exhibited TWIP-like plastic deformation behavior with an increasing work-hardening rate during the early to middle stages of plastic deformation. This plastic deformation behavior is effective in achieving both the low yield stress and high strength required to develop a high-performance balloon-expandable stent. The 8Mn+2Si-added alloy retained the CoWSi type Laves phase even after solution treatment, such that the ductility decreased but the strength improved. Additions of Mn and Si are effective in improving the ductility and strength of the Co-Cr-W-Ni alloy, respectively. -
2021.1.20
An open-access paper was published in MDPI's "Biomolecules" (IF=4.082) on osteoblast disruption, which is closely related to the formation of bone matrix in cancer (melanoma) bone metastases.
Aira Matsugaki*, Yumi Kimura, Ryota Watanabe, Fumihito Nakamura, Ryo Takehana, Takayoshi Nakano*:
Impaired alignment of bone matrix microstructure associated with disorganized osteoblast arrangement in malignant melanoma metastasis,
Biomolecules, 11(2), (2021), 131: 1-9.
https://doi.org/10.3390/biom11020131Click here for this paper.
Click here for this PDF.Abstract
Malignant melanoma favors spreading to bone, resulting in a weakened bone with a high fracture risk. Here, we revealed the disorganized alignment of apatite crystals in the bone matrix associated with the homing of cancer cells by developing an artificially controlled ex vivo melanoma bone metastasis model. The ex vivo metastasis model reflects the progressive melanoma cell activation in vivo, resulting in decreased bone mineral density and expression of MMP1-positive cells. Moreover, less organized intercellular connections were observed in the neighboring osteoblasts in metastasized bone, indicating the abnormal and randomized organization of bone matrix secreted by disconnected osteoblasts. Our study revealed that the deteriorated microstructure associated with disorganized osteoblast arrangement was a determinant of malignant melanoma-related bone dysfunction.
Keywords: malignant melanoma; ex vivo metastasis model; bone tissue microstructure; osteoblast -
2021.1.19
Dr. Nakano's column article appeared in today's Nikkan Kogyo Shimbun.
Thank you for your filial piety,
Nikkan Kogyo Shimbun, January 19, 2021, Morning Edition, page 23 (Science and Technology, University)
-
2021.1.18
Our paper on micro-simulation of crystal aggregate microstructure formation in AM has been published in the Journal of the Japan Institute of Metals.
Jun Kubo, Yuichiro Koizumi, Takuya Ishimoto and Takayoshi Nakano:
Microscopic simulation by improved CA method for clarifying the mechanism of crystal aggregate microstructure formation in laser additive manufacturing,
Journal of the Japan Institute of Metals and Materials, (2021), in press.
DOI: https://doi.org/10.2320/jinstmet.J2020028Click here for this paper.
-
2021.1.13
An article on the suppression of crack formation in heat-resistant materials by metal 3D printers appeared on page 25 of today's Nikkan Kogyo Shimbun.
Heat-Resistant Material Crack Prevention by Metal 3D Printer at Osaka University
Nikkan Kogyo Shimbun, Jan. 13, 2021, Morning Edition, page 25 (Science and Technology, University)
Click here for this electric version
-
2021.1.5
The proceedings of Thermec2021 was published in Materials Science Forum.
K. Ueki, S. Yanagihara, K. Ueda, M. Nakai, T. Nakano and T. Narushima:
Improvement of Strength and Ductility by Combining Static Recrystallization and Unique Heat Treatment in Co-20Cr-15W-10Ni Alloy for Stent Application,
Materials Science Forum, 1016, (2021), 1503-1509.M. Todai, T. Nagase and T. Nakano:
Fabrication of Be-Ta Ti Alloys without Pre-Alloyed Powders via SLM,
Materials Science Forum, 1016, (2021), 1797-1801.
