フィリピンにおける公衆衛生に関する留学記

As a second-year resident at the University of Tokushima Hospital, I report on my experience of overseas training in the Philippines under the training program of the National Institute of Health Sciences. The National Institute of Health Sciences is an institution that conducts education, investigation, and research related to health, medical care, and welfare, and I trained for two months in the Department of Clinical Training in Community Health, Specialty Course III. In addition to the out-of-hospital training at the Ministry of Health, Labour and Welfare, Chiba Prefectural Government, and National Institute of Infectious Diseases, the one week overseas training in the Philippines（Manila） consisted mainly of lectures and training on mosquito-borne infectious diseases, zoonosis, and parasites at the University of the Philippines, Philippine General Hospital, Suburban Health Center, and WHO Western Pacific Office. Infectious diseases are very different from those in Japan. The actual observation made us understand that rabies and parasitic infections are raging in the Philippines due to the sanitary conditions of the living environment, which is very different from that of Japan. By learning about the medical system at overseas medical facilities, we were able to rethink deeply about the merits of the Japanese medical system and the direction it should take in the future from various perspectives

Spectral Duality in Integrable Systems from AGT Conjecture

We describe relationships between integrable systems with N degrees of freedom arising from the AGT conjecture. Namely, we prove the equivalence (spectral duality) between the N-cite Heisenberg spin chain and a reduced gl(N) Gaudin model both at classical and quantum level. The former one appears on the gauge theory side of the AGT relation in the Nekrasov-Shatashvili (and further the Seiberg-Witten) limit while the latter one is natural on the CFT side. At the classical level, the duality transformation relates the Seiberg-Witten differentials and spectral curves via a bispectral involution. The quantum duality extends this to the equivalence of the corresponding Baxter-Schrodinger equations (quantum spectral curves). This equivalence generalizes both the spectral self-duality between the 2x2 and NxN representations of the Toda chain and the famous AHH duality

Behavior of hydrogen atom at Nafion-Pt interface

We present a mechanism depicting how a hydrogen atom migrates from a platinum catalyst to a Nafion membrane using ab initio calculations based on density functional theory (DFT). The H atom initially adsorbed on Pt is extracted by the sulfonate group (-SO3-), which is a part of the side chain of Nafion. We found partial electron transfer from the H atom to the Pt, which directly binds to the -SO3- group, through this reaction. The electron-poor H atom conducts in Nafion, and the partial electron transfer from the H atom results in the generation of electric power in polymer electrolyte fuel cells (PEFCs). © 2005 Elsevier Ltd. All rights reserved

Spin polarization effects on O2 dissociation from heme-O 2 adduct

We consider singlet and triplet iron-porphyrin-O2 (FeP-O 2) adducts to investigate spin polarization effects on the FeP-O 2 interaction using ab initio calculations based on density functional theory (DFT). The presence of the imidazole (Im) ligand induces spin polarization from O2 to Fe in the triplet (Im)FeP-O2 adduct. The O-O bond of the triplet (Im)FeP-O2 is weaker than that of the triplet FeP-O2 because of this spin polarization effects. Our results suggest that magnetization of heme or heme-based nanomaterials may be utilized as cathode electrode catalysts in polymer electrolyte fuel cells (PEFCs). ©2005 The Japan Society of Applied Physics

Hydrogenase-based nanomaterials as anode electrode catalyst in polymer electrolyte fuel cells

We consider hydrogenase-based nanomaterials for possible use as anode electrode catalysts in polymer electrolyte fuel cells (PEFCs). We choose Fe-only hydrogenase component of Desulfovibrio desulfuricans (DdHase) as a hydrogenase complex, and investigate its catalytic activity for H2 dissociation using ab initio calculations based on density functional theory (DFT). We found two possible H-H bond cleavage pathways, which are heterolytic and possess low activation barriers. Moreover, the H2 dissociation can be promoted by inducing spin polarization of the H2 adduct. We report that hydrogenase or hydrogenase-based nanomaterials can manipulate to exhibit the catalytic activity equivalent to the well-known platinum catalyst. © 2004 Elsevier Ltd. All rights reserved

Behavior of hydrogen atom at Nafion-Pt interface

We present a mechanism depicting how a hydrogen atom migrates from a platinum catalyst to a Nafion membrane using ab initio calculations based on density functional theory (DFT). The H atom initially adsorbed on Pt is extracted by the sulfonate group (–SO3−), which is a part of the side chain of Nafion. We found partial electron transfer from the H atom to the Pt, which directly binds to the –SO3− group, through this reaction. The electron-poor H atom conducts in Nafion, and the partial electron transfer from the H atom results in the generation of electric power in polymer electrolyte fuel cells (PEFCs)

O2 binding to cytochrome c oxidase-inspired nanomaterials

We investigate O2 binding to cytochrome c oxidase (CcO)-inspired nanomaterials using ab initio density functional calculations. We consider iron-porphyrin (FeP) and copper-(imidazole)3 [Cu(Im)3] as a representative of the active binuclear center, and explore the effect of the Cu(Im)3 on the FeP–O2 adduct in relation to the geometric, vibrational, electronic and energetic properties. We find that the Cu(Im)3 induces the weak O–O and Fe–O bonds mainly because of the electron transfer to the O2 and the spin polarization of the Fe and O2 by bridging the O2 between the Fe and Cu, possibly resulting in the facile O2 dissociation

Ab initio study of H2 desorption from magnesium hydride MgH 2 cluster

In the present study, we investigate H2 desorption from a magnesium hydride MgH2 cluster by performing total energy calculations based on the density functional theory (DFT). We calculate the potential energy surface (PES) for the H2 desorption from a (MgH 2), cluster. According to the total atomic charges of the Mg and H atoms at the initial (MgH2)5 cluster, the Mg-H bond is ionic-like. Because of this, the activation barrier for the H2 desorption is considerably high (3.30 eV). Moreover, the structural relaxation for the system, allowing for only the two Mg atoms closest to the two desorbing H atoms, does not largely affect the potential energy of the system. The results indicate that the ionic-like Mg-H interaction is related to the thermodynamical stability of MgH2. © 2004 The Physical Society of Japan

Ab initio study of cyclohexane dehydrogenation with a transition metal (Pt, Pd, Ni and Cu) atom

To investigate cyclohexane dehydrogenation by a transition metal M (M: Pt, Pd, Ni and Cu) atom, we perform total energy calculations, based on the density functional theory. We consider the process where cyclohexane approaches the M atom. Upon interacting with the M atom, the M atom draws an H atom from the cyclohexane, forming an H-M bond. With a broken C-H bond, the dehydrogenated cyclohexane separates from the M atom. Of the M elements we investigated, a Pt atom exhibited the highest reactivity. In breaking the C-H bond of the cyclohexane, the σ donation dominates for a Pd and Cu atom as compared with the Pt atom, and the π back-donation dominates for a Ni atom as compared with the Pt atom. The results indicate that the excess charge transfer requires more energy for breaking the C-H bond of the cyclohexane with the Pd, Ni and Cu atom. ©2004 The Physical Society of Japan