Tohoku University · Medicine
Professor Masahiro Yamada's research lab specializes in advanced functional materials and their applications in photonics, materials chemistry, and biomedical engineering. The lab focuses on the design and fabrication of novel functional materials such as periodically poled lithium niobate (LiNbO3) for electro-optic devices, spin-crossover complexes for smart materials with tunable magnetic and optical properties, and biocompatible bone substitutes for regenerative medicine. Key research directions include room-temperature domain engineering in ferroelectrics, molecular engineering of spin-crossover systems, and the development of multifunctional materials for optoelectronic and biomedical applications.
Figures are computed from collected data and may differ slightly.
A novel method of fabricating a periodic domain structure with ideal laminar domains in LiNbO3 by applying an external field at room temperature is proposed. The method allows a high blue beam power of 20.7 mW and a high conversion efficiency of 600%/W cm2 to be obtained.
It is necessary to improve the biocompatibility of currently available bone substitutes and to strike an appropriate balance between bioabsorption and volume maintenance to achieve ideal bone remodeling.
A family of spin-crossover (SC) complexes, [Fe(II)H(3)L(Me)]Cl.X (X(-) = PF(6) (-), AsF(6) (-), SbF(6) (-), CF(3)SO(3) (-)), 1-4, has been synthesized, in which H(3)L(Me) denotes the hexadentate N(6) tripod-like ligand tris[2-{[(2-methylimidazol-4-yl)methylidene]amino}ethyl]amine, containing three imidazole groups, with a view to establishing the effect of the counter anion on the SC behavior. These complexes have been found to crystallize in the same monoclinic crystal system with similar cell
A series of two-dimensional (2D) spin crossover complexes, [FeIIH3L(Me)][FeIIL(Me)]X (X-=ClO4-, BF4-, PF6-, AsF6-, SbF6-) 1-5, have been synthesized, where H3L(Me) denotes an hexadentate N6 tripodlike ligand containing three imidazole groups, tris[2-(((2-methylimidazol-4-yl)methylidene)amino)ethyl]amine. Compounds 1-5 exhibit a two-step (HS-[FeIIH3L(Me)](2+) + HS-[FeIIL(Me)]-) <--> (HS-[FeIIH3L(Me)](2+) + LS-[FeIIL(Me)]-) <--> (LS-[FeIIH3L(Me)](2+) + LS-[FeIIL(Me)]-) spin-transition. The crystal
Three kinds of electro-optic devices composed of the inverted domains in LiNbO3 substrates were fabricated. The devices are induced and controlled by applying an electric field. The three devices are: (i) a cylindrical lens with an aperture of 340 μm and length of 10 mm, which can tune the focusing length from 20 to 50 mm depending on an electric field ranging from 250 to 150 V/mm, (ii) an optical switching device composed of a periodically inverted domain structure, which can reflect the whole
For the first time, the fabrication of a periodically reversed domain structure for LiNbO3 has been achieved at room temperature. The domain boundary is perpendicular to the positive c-face and is very deep which is advantageous for quasiphasematching SHG.
In this study, long term dextran sulphate sodium administration was studied to ascertain whether colorectal carcinoma could be produced in patients with long standing ulcerative colitis. Simultaneously, changes in the intestinal microflora were analysed. Low grade to high grade dysplasia was seen in three of the five hamsters treated with 1% dextran sulphate sodium solution for 100 days, while no dysplasia was detected in the eight animals concomitantly treated with metronidazole, an antianerobi
The purpose of the present study was to compare alpha- and beta-tricalcium phosphate (TCP) as bone graft material for augmenting highly resorbed alveolar ridges. The cranial bones of 15 rabbits were used. Three titanium chambers filled with porous blocks of alpha-TCP, beta-TCP, or blood clots were placed in each slit. The two TCP blocks had similar inner/outer structures and purities. Animals were sacrificed after 2, 4, and 8 weeks. Specimens were embedded in polyester resin as nondecalcified sp
Despite its proven cytotoxicity, poly-methyl methacrylate (PMMA) resin is one of the most frequently and extensively used materials in dental practice. This study hypothesized that an anti-oxidant amino acid, N-acetyl cysteine (NAC), has the potential to detoxify this material. Ten percent of the rat dental pulp cells were viable when cultured on the PMMA resin for 24 hours, while over 70% of the cells were viable on the NAC-added resin. Nearly all suppressed alkaline phosphatase activity, matri
Bragg diffraction by an electrically induced and controlled grating composed of periodically inverted domains in a lithium niobate crystal is discussed theoretically and experimentally. As the applications of the Bragg-diffraction grating, experimental results of an optical switch with one input port and six output ports and a wide band optical amplitude modulator for a violet-blue light with the wide frequency bandwidth from direct current to 1 GHz are presented.
In C(4) plants, mesophyll (M) chloroplasts are randomly distributed along the cell walls, while bundle sheath (BS) chloroplasts are typically located in either a centripetal or centrifugal position. We investigated whether these intracellular positions are affected by environmental stresses. When mature leaves of finger millet (Eleusine coracana) were exposed to extremely high intensity light, most M chloroplasts aggregatively re-distributed to the BS side, whereas the intracellular arrangement
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