Abstract: A proton-conductive cell structure includes an air electrode, a hydrogen electrode, and a solid electrolyte layer disposed between the air electrode and the hydrogen electrode, wherein the solid electrolyte layer includes at least a first solid electrolyte layer formed of a compact material. The first solid electrolyte layer includes a metal oxide having a perovskite structure and represented by Formula 1 below, a ratio of Sr to a total amount of Ba and Sr in an air-electrode-side near-surface region of the first solid electrolyte layer is 0.4 or more, and a ratio of Sr to a total amount of Ba and Sr in a hydrogen-electrode-side near-surface region of the first solid electrolyte layer is 0.003 to 0.3.

Abstract: An optical fiber includes a core, and a cladding. When a refractive index of silica glass is set as no, a refractive index of the core is set as n1, and a refractive index of the cladding is set as n2, a relative refractive index difference ? defined by Expression (1): ?[%]=100×(n12?n22)/2n02??(1) is 0.2% or higher. A ratio of a maximum value of a concentration of the dopant composed of the alkali metal element or the alkaline-earth metal element in the cladding to a maximum value of a concentration of the dopant composed of the alkali metal element or the alkaline-earth metal element in the core is 0.06 or higher and 0.25 or lower.

Abstract: The present embodiment relates to an optical fiber preform producing method for effectively suppressing breaking of symmetry of refractive index profile defined on a cross section of an optical fiber preform. In the present embodiment, when producing a center glass rod forming a part of the optical fiber preform, prior to grinding an outer peripheral portion of an intermediate glass rod in which an element-doped region is formed by collapse, an non-defective article determination regarding the intermediate glass rod to be a grinding target is performed.

Abstract: The present embodiment relates to an optical fiber preform producing method for effectively suppressing breaking of symmetry of refractive index profile defined on a cross section of an optical fiber preform. In the present embodiment, when producing a center glass rod forming a part of the optical fiber preform, prior to grinding an outer peripheral portion of an intermediate glass rod in which an element-doped region is formed by collapse, an non-defective article determination regarding the intermediate glass rod to be a grinding target is performed.