Analysis of the Pathogenesis of Experimental Autoimmune Optic Neuritis

Optic neuritis associated with multiple sclerosis has a strong association with organ-specific autoimmune disease. The goal of our research is to establish an optimal organ-specific animal model to elucidate the pathogenetic mechanisms of the disease and to develop therapeutic strategies using the model. This paper is divided into five sections: (1) clinical picture of optic neuritis associated with multiple sclerosis, (2) elucidation of pathogenesis using animal models with inflammation in optic nerve and spinal cord, (3) clinical relevance of concurrent encephalomyelitis in optic neuritis model, (4) retinal damage in a concurrent multiple sclerosis and optic neuritis model, and (5) development of novel therapies using mouse optic neuritis model. Advanced therapies using biologicals have succeeded to control intractable optic neuritis in animal models. This may ultimately lead to prevention of vision loss within a short period from acute onset of optic neuritis in human. By conducting research flexibly, ready to switch from the bench to the bedside and from the bedside to the bench as the opportunity arises, this strategy may help to guide the research of optic neuritis in the right direction

Oxy-trifluoromethylation of alkenes and its application to the synthesis of β-trifluoromethylstyrene derivatives

AbstractOxy-trifluoromethylation of di-substituted styrenes and dienes was achieved by using Cu/Togni's reagent system. Not only gem-di-substituted styrenes, but also a β-methylstyrene derivative were transformed to the corresponding oxy-trifluoromethylation products. 1,4-Addition products were obtained selectively in the reaction of mono-substituted dienes. These reactions provide a new approach for the synthesis of β-trifluoromethyl styrene derivatives

Novel BiS2-based layered superconductor Bi4O4S3

Exotic superconductivity has often been discovered in materials with a layered (two-dimensional) crystal structure. The low dimensionality can affect the electronic structure and can realize high transition temperatures (Tc) and/or unconventional superconductivity mechanisms. As standard examples, we now have two types of high-Tc superconductors. The first group is the Cu-oxide superconductors whose crystal structure is basically composed of a stacking of spacer (blocking) layers and superconducting CuO2 layers.1-4 The second group is the Fe-based superconductors which also possess a stacking structure of spacer layers and superconducting Fe2An2 (An = P, As, Se, Te) layers.5-13 In both systems, dramatic enhancements of Tc are achieved by optimizing the spacer layer structure, for instance, a variety of composing elements, spacer thickness, and carrier doping levels with respect to the superconducting layers. In this respect, to realize higher-Tc superconductivity, other than Cu-oxide and Fe-based superconductors, the discovery of a new prototype of layered superconductors needs to be achieved. Here we show superconductivity in a new bismuth-oxysulfide layered compound Bi4O4S3. Crystal structure analysis indicates that this superconductor has a layered structure composed of stacking of Bi4O4(SO4)1-x and Bi2S4 layers; the parent compound (x = 0) is Bi6O8S5. Band calculation suggests that Bi4O4S3 (x = 0.5) is metallic while Bi6O8S5 (x = 0) is a band insulator with Bi3+. Furthermore, the Fermi level for Bi4O4S3 is just on the peak position of the partial density of states of the Bi 6p orbital within the BiS2 layer. The BiS2 layer is a basic structure which provides another universality class for layered superconducting family, and this opens up a new field in the physics and chemistry of low-dimensional superconductors.Comment: 13 pages, 3 figures, 1 tabl

Pressure-induced volumetric negative thermal expansion in CoZr2 superconductor

We investigate the thermal expansion and superconducting properties of a CuAl2-type (tetragonal) superconductor CoZr2 under high pressures. We perform high-pressure synchrotron X-ray diffraction in a pressure range of 2.9 GPa < P < 10.4 GPa and discover that CoZr2 exhibits volumetric negative thermal expansion under high pressures. Although the uniaxial positive thermal expansion (PTE) along the a-axis is observed under ambient pressure, that is suppressed by pressure, while the large uniaxial negative thermal expansion (NTE) along the c-axis is maintained under the pressure regime. As a result of a combination of the suppressed uniaxial PTE along the a-axis and uniaxial NTE along the c-axis, volumetric negative thermal expansion is achieved under high pressure in CoZr2. The mechanisms of volumetric NTE would be based on the flexible crystal structure caused by the soft Co-Co bond as seen in the iso-structural compound FeZr2, which exhibits uniaxial NTE along the c-axis. We also perform high-pressure electrical resistance measurements of CoZr2 to confirm the presence of superconductivity under the examined pressure regime in the range of 0.03 GPa < P < 41.9 GPa. We confirm the presence of superconductivity under all pressures and observe dome-like shape pressure dependence of superconducting transition temperature. Because of the coexistence of two phenomena, which are volumetric NTE and superconductivity, in CoZr2 under high pressure, the coexistence would be achievable under ambient pressure by tuning chemical compositions after our present observation.Comment: 22 pages, 7 figures, supporting informatio