Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, an actuator, a controller, and a ramp. The magnetic head is configured to record data on and reproduce data from the magnetic disk. The actuator is configured to move the magnetic head relative to the magnetic disk. The controller is configured to control the actuator. The ramp is configured to hold the magnetic head. The controller is configured to, in a retract operation for causing the actuator to retract the magnetic head to the ramp, alternate detection of a back electromotive force of the actuator and application of a voltage corresponding to the back electromotive force to the actuator, and skip the detection of the back electromotive force a predetermined number of times in response to an event that the magnetic head moves at a speed outside a predetermined range.

Abstract: An exploration method includes: a step of exploring a natural resource on a satellite, a minor planet, or a planet; a step of acquiring the natural resource detected by the exploration; and a step of storing the acquired natural resource.

Abstract: An object of the present invention is to provide a method for recovering a rare earth element, including subjecting a workpiece containing at least a rare earth element and an iron group element to an oxidation treatment, then turning the treatment environment into an environment where carbon is present, and subjecting an oxidation-treated workpiece to a heat treatment, thereby separating a rare earth element in the form of an oxide from an iron group element, according to which an oxide of a rare earth element can be efficiently separated from an iron group element at low treatment cost, and also wear and damage to the treatment container can be suppressed to allow the container to be used repeatedly for a long period of time.

Abstract: An object of the present invention is to provide a method for recovering a heavy rare earth element from a workpiece containing at least a heavy rare earth element and an iron group element, which can be put into practical use as a low-cost, simple recycling system. The method for recovering a heavy rare earth element from a workpiece containing at least a heavy rare earth element and an iron group element of the present invention as a means for resolution is characterized by including at least the following step: a workpiece is subjected to an oxidation treatment or mixed with an oxidation-treated R—Fe—B based magnet alloy, and then subjected to a heat treatment in the presence of carbon at a temperature of 1000° C. or more, thereby separating a heavy rare earth element in the form of an oxide from an iron group element.

Abstract: An object of the present invention is to provide a method for recovering a rare earth element from a workpiece containing at least a rare earth element and an iron group element, which can be put into practical use as a low-cost, simple recycling system. The method for recovering a rare earth element from a workpiece containing at least a rare earth element and an iron group element of the present invention as a means for resolution is characterized by including at least a step of separating a rare earth element in the form of an oxide from an iron group element by subjecting a workpiece to an oxidation treatment, then turning the treatment environment into an environment where carbon black is present, and subjecting the oxidation-treated workpiece to a heat treatment at a temperature of 1000° C. or more in an inert gas atmosphere or in vacuum.

Abstract: An object of the present invention is to provide a method according to which a rare earth element can be efficiently recovered from a workpiece containing at least a rare earth element and an iron group element, and also wear and damage to the treatment container can be suppressed, allowing the container to be used repeatedly for a long period of time. The method of the present invention as a means for resolution is characterized in that in the heat treatment of an oxidation-treated workpiece in the presence of carbon, when the oxidation-treated workpiece is placed in a treatment container, a carbon substance is interposed between the oxidation-treated workpiece and the bottom surface of the container, and the heat treatment is performed in an inert gas atmosphere or in vacuum at a temperature of 1300° C. or more.

Abstract: An object of the present invention is to provide a method for recovering a rare earth element, including subjecting a workpiece containing at least a rare earth element and an iron group element to an oxidation treatment, then turning the treatment environment into an environment where carbon is present, and subjecting an oxidation-treated workpiece to a heat treatment, thereby separating a rare earth element in the form of an oxide from an iron group element, according to which an oxide of a rare earth element can be efficiently separated from an iron group element at low treatment cost, and also wear and damage to the treatment container can be suppressed to allow the container to be used repeatedly for a long period of time.

Abstract: An object of the present invention is to provide a method according to which a rare earth element can be efficiently recovered from a workpiece containing at least a rare earth element and an iron group element, and also wear and damage to the treatment container can be suppressed, allowing the container to be used repeatedly for a long period of time. The method of the present invention as a means for resolution is characterized in that in the heat treatment of an oxidation-treated workpiece in the presence of carbon, when the oxidation-treated workpiece is placed in a treatment container, a carbon substance is interposed between the oxidation-treated workpiece and the bottom surface of the container, and the heat treatment is performed in an inert gas atmosphere or in vacuum at a temperature of 1300° C. or more.

Abstract: An object of the present invention is to provide a method for recovering a heavy rare earth element from a workpiece containing at least a heavy rare earth element and an iron group element, which can be put into practical use as a low-cost, simple recycling system. The method for recovering a heavy rare earth element from a workpiece containing at least a heavy rare earth element and an iron group element of the present invention as a means for resolution is characterized by including at least the following step: a workpiece is subjected to an oxidation treatment or mixed with an oxidation-treated R—Fe—B based magnet alloy, and then subjected to a heat treatment in the presence of carbon at a temperature of 1000° C. or more, thereby separating a heavy rare earth element in the form of an oxide from an iron group element.

Abstract: An object of the present invention is to provide a method for recovering a rare earth element from a workpiece containing at least a rare earth element and an iron group element, which can be put into practical use as a low-cost, simple recycling system. The method for recovering a rare earth element from a workpiece containing at least a rare earth element and an iron group element of the present invention as a means for resolution is characterized by including at least a step of separating a rare earth element in the form of an oxide from an iron group element by subjecting a workpiece to an oxidation treatment, then turning the treatment environment into an environment where carbon black is present, and subjecting the oxidation-treated workpiece to a heat treatment at a temperature of 1000° C. or more in an inert gas atmosphere or in vacuum.

Abstract: Provided are a high-quality graphene or graphite thin film compatible with a large surface area, a manufacturing method that can epitaxially form the graphene or graphite thin film on a Si substrate, a thin film structure, and an electronic device having the same. The present invention provides a graphene or graphite thin film formed on a cubic SiC crystal thin film having a (111) orientation formed on a Si substrate, the cubic SiC crystal thin film being used as a base material. Additionally, the development of ultra-high-speed devices that support next-generation high-speed communication services can be advanced by means of an electronic device having a graphene or graphite thin film structure grown as a crystal on a substrate.