Abstract: A water electrolyzer includes an electrochemical cell including an anode and a cathode, an electrolyte solution, a heater, a voltage applicator, and a controller. The heater heats the electrolyte solution. The voltage applicator applies a voltage between the anode and the cathode. The electrochemical cell includes nickel. In startup of the water electrolyzer, the controller causes the heater to increase the temperature of the electrolyte solution by heating and causes the voltage applicator to start application of a voltage when the temperature of the electrolyte solution is less than a predetermined threshold value.

Abstract: A water electrolysis cell includes an anode, a cathode, and an anion-exchange membrane disposed between the anode and the cathode. The anode includes a catalyst layer disposed on the anion-exchange membrane and an anode gas diffusion layer disposed on the catalyst layer. The anode gas diffusion layer includes metal fiber. In the metal fiber, a section constituting a surface of the metal fiber is composed of nickel.

Abstract: A water electrolyzer includes an electrochemical cell including an anode and a cathode, an electrolyte solution, a voltage applicator, and a controller. The voltage applicator applies a voltage between the anode and the cathode. The electrochemical cell includes nickel. In the shutdown of the water electrolyzer, the controller causes the voltage applicator to apply the voltage at least when the temperature of the electrolyte solution is equal to or more than a predetermined threshold value.

Abstract: The electrode catalyst ink for a water electrolysis cell includes a catalyst including a layered double hydroxide, an organic polymer, and a solvent. The Hansen solubility parameter distance Ra1 between the solvent and the catalyst is 15.0 MPa½ or more and less than 20.5 MPa½. The Hansen solubility parameter distance Ra2 between the solvent and the organic polymer is 10.0 MPa½ or more and 14.0 MPa½ or less.

Abstract: The electrode catalyst ink includes a catalyst including a layered double hydroxide, an organic polymer, and a solvent. The solvent includes a first solvent, a second solvent, and a third solvent. The third solvent has a boiling point higher than a boiling point of the first solvent and higher than a boiling point of the second solvent. The Hansen solubility parameter distance Ra1 [MPa1/2] between the third solvent and the catalyst and the Hansen solubility parameter distance Ra2 [MPa1/2] between the third solvent and the organic polymer satisfy a relationship of 2.08Ra1?16.0?Ra2?2.08Ra1?13.5.

Abstract: An electrode catalyst for a water electrolysis cell includes a catalyst, and a polymer of intrinsic microporosity having a Tröger's base skeleton containing a quaternary ammonium group. A water electrolysis cell includes an anode, a cathode, and an electrolyte membrane. The electrolyte membrane is disposed between the anode and the cathode. At least one selected from the group consisting of the anode and the cathode includes the electrode catalyst.

Abstract: An electrode catalyst for a water electrolysis cell includes a catalyst and a polymer of intrinsic microporosity, and the polymer of intrinsic microporosity is neutral.

Abstract: An electrode catalyst for a water electrolysis cell includes a catalyst, a support, and an organic compound. The catalyst is a layered double hydroxide that contains a chelating agent. The support contains a transition metal. The organic compound has an anionic functional group.

Abstract: A catalyst includes a layered double hydroxide and a metal particle. The layered double hydroxide includes ions of at least two transition metals. The metal particle includes at least one transition metal. The metal particle has a surface coated with the layered double hydroxide.

Abstract: A fuel cell system includes: a fuel cell that includes a cathode and an anode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes, with an oxidant, the mediator reduced by the cathode; an oxidant feed path that is connected to the regenerator, wherein through the oxidant feed path, the oxidant to be supplied to the regenerator flows; a reformer; a combustor that heats the reformer; and a first heat exchanger that exchanges heat between combustion exhaust discharged from the combustor and the oxidant to be supplied to the regenerator.

Abstract: An eye movement analysis system includes an image-capturing unit configured to capture a moving image including at least one of a right eye and a left eye of a subject and a comparison target on a surface of a face of the subject, and an analysis unit configured to analyze a movement of an eyeball of the at least one of the right eye and the left eye of the subject, based on a relationship between the at least one of the right eye and the left eye of the subject and the comparison target on the moving image captured by the image-capturing unit.

Abstract: A fuel cell system includes: a fuel cell that includes an anode and a cathode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes the mediator reduced by the cathode; a first path that leads from the cathode to the regenerator and through which the mediator reduced by and discharged from the cathode is guided to the regenerator; a second path that leads from the regenerator to the cathode and through which the mediator oxidized at the regenerator is returned to the cathode; and a first heat exchanger that exchanges heat between a first fluid and a second fluid, the first fluid being a fluid flowing in the first path and containing the mediator reduced by cathode, and the second fluid being a fluid flowing in the second path and containing the mediator oxidized at the regenerator.

Abstract: A layered double hydroxide of the present disclosure includes two or more transition metals and a chelating agent. The layered double hydroxide has an average particle diameter of 10 nm or less.

Abstract: A fuel cell system includes a fuel cell, a regenerator, an oxidant feed path, a gas discharge path, and a heat exchanger. The fuel cell includes an anode and a cathode and reduces a mediator with the cathode. The regenerator oxidizes, with an oxidant, the mediator reduced by the cathode. Through the oxidant feed path, the oxidant is guided to the regenerator. Through the gas discharge path, the gas present inside the regenerator is guided out of the regenerator. The heat exchanger heats the oxidant by exchanging heat between the oxidant flowing in the oxidant feed path and the gas flowing in the gas discharge path.

Abstract: Provided is a threaded-hole inspection device having high inspection precision. An incomplete thread ridge portion of a gauge portion 5 of a thread gauge 1 is removed, a phase-positioning portion 8 for positioning a tip-side start point 7 of a complete thread ridge at a prescribed phase when the thread gauge 1 is mounted on a rotating-shaft portion 2 is provided to a fastening portion 6 of the thread gauge 1 that is to be fastened to the rotating-shaft portion 2, and a phase-positioning engaging portion 9 that is to engage with the phase-positioning portion 8 is provided to the rotating-shaft portion 2.

Abstract: A fuel cell system includes: a fuel cell that includes a cathode and an anode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes, with an oxidant, the mediator reduced by the cathode; an oxidant feed path that is connected to the regenerator, wherein through the oxidant feed path, the oxidant to be supplied to the regenerator flows; a reformer; a combustor that heats the reformer; and a first heat exchanger that exchanges heat between combustion exhaust discharged from the combustor and the oxidant to be supplied to the regenerator.

Abstract: A fuel cell system includes a fuel cell, a regenerator, an oxidant feed path, a gas discharge path, and a heat exchanger. The fuel cell includes an anode and a cathode and reduces a mediator with the cathode. The regenerator oxidizes, with an oxidant, the mediator reduced by the cathode. Through the oxidant feed path, the oxidant is guided to the regenerator. Through the gas discharge path, the gas present inside the regenerator is guided out of the regenerator. The heat exchanger heats the oxidant by exchanging heat between the oxidant flowing in the oxidant feed path and the gas flowing in the gas discharge path.

Abstract: A fuel cell system includes: a fuel cell that includes an anode and a cathode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes the mediator reduced by the cathode; a first path that leads from the cathode to the regenerator and through which the mediator reduced by and discharged from the cathode is guided to the regenerator; a second path that leads from the regenerator to the cathode and through which the mediator oxidized at the regenerator is returned to the cathode; and a first heat exchanger that exchanges heat between a first fluid and a second fluid, the first fluid being a fluid flowing in the first path and containing the mediator reduced by cathode, and the second fluid being a fluid flowing in the second path and containing the mediator oxidized at the regenerator.

Abstract: A fuel cell system includes a fuel cell that includes an anode and a cathode and generates electricity by reducing a mediator at the cathode, a regenerator that oxidizes the mediator, a fuel gas feed path through which fuel gas to be supplied to the anode flows, a humidifier that is disposed in the fuel gas feed path and humidifies the fuel gas, and a water collection path that extends from the regenerator to the humidifier and guides to the humidifier at least one selected from steam produced at the regenerator and condensation formed from the steam.

Abstract: Provided is a threaded-hole inspection device having high inspection precision. An incomplete thread ridge portion of a gauge portion 5 of a thread gauge 1 is removed, a phase-positioning portion 8 for positioning a tip-side start point 7 of a complete thread ridge at a prescribed phase when the thread gauge 1 is mounted on a rotating-shaft portion 2 is provided to a fastening portion 6 of the thread gauge 1 that is to be fastened to the rotating-shaft portion 2, and a phase-positioning engaging portion 9 that is to engage with the phase-positioning portion 8 is provided to the rotating-shaft portion 2.