The present disclosure provides HRG-Mn.sub.3O.sub.4 hybrid nanoparticles. The HRG-Mn.sub.3O.sub.4 hybrid nanoparticles do not pose any cytotoxicity at normal physiological conditions and therefore they are nontoxic and biocompatible at physiological conditions. The HRG-Mn.sub.3O.sub.4 hybrid nanoparticles under exposure of laser light cause massive cellular damage indicating their potential use for photodynamic therapy of cancer. The HRG-Mn.sub.3O.sub.4 hybrid nanoparticles enhance the magnetic resonance signals from cancer cells and exhibit excellent MRI contrast property for tumor imaging and are therefore useful contrast agent.

A method for producing lithium hydroxide that allows reducing a load of removing divalent or more ions with an ion-exchange resin is provided. The method for producing lithium hydroxide includes steps (1) to (3) below. (1) a neutralization step: a step of adding an alkali to a first lithium chloride containing liquid to obtain a post-neutralization liquid, (2) an ion-exchange step: a step of bringing the post-neutralization liquid into contact with an ion-exchange resin to obtain a second lithium chloride containing liquid, and (3) a conversion step: a step of electrodialyzing the second lithium chloride containing liquid to obtain a lithium hydroxide containing liquid. Since this producing method allows roughly removing divalent or more ions in the neutralization step, a load of metal removal with the ion-exchange resin is reducible.

A method for preparing a cathode active material is provided. The method for preparing a cathode active material can comprise the steps of: preparing a first metal oxide; preparing a second metal oxide having an oxygen ratio lower than that of the first metal oxide by heat treating the first metal oxide in a nitrogen-containing gas atmosphere; and preparing a lithium metal oxide by firing the second metal oxide and a lithium salt.

A positive electrode active material that is used in a high-temperature operation type lithium ion solid secondary battery, wherein the positive electrode active material is made of oxide particles, which contains a first transition element and does not include an alkali metal.

The present invention relates an indicator system for assessing a reduction state of unconsolidated material that includes a delivery tube defining an interior chamber, and a substrate disposed within the interior chamber and including a reactive coating thereon. The reactive coating is at least partially removable from the substrate upon exposure to a reducing condition of unconsolidated material over a period of time. An indicator device including a reactive coating comprising a manganese oxide is also disclosed.

The present invention relates an indicator system for assessing a reduction state of unconsolidated material that includes a delivery tube defining an interior chamber, and a substrate disposed within the interior chamber and including a reactive coating thereon. The reactive coating is at least partially removable from the substrate upon exposure to a reducing condition of unconsolidated material over a period of time. An indicator device including a reactive coating comprising a manganese oxide is also disclosed.

The disclosure relates to porous manganese oxide nanoparticles which include flocculated primary nanoparticles, with air pores formed between the primary nanoparticles. Unlike in the prior art, the porous manganese oxide nanoparticles of the disclosure have 6 nm or less MnO.sub.2 primary nanoparticles and Mn.sub.3O.sub.4 primary nanoparticles uniformly mixed and flocculated, exhibiting a 16 times higher specific surface area as compared with the conventional manganese oxide particles and superior storage characteristics and stability.

The disclosure relates to porous manganese oxide nanoparticles which include flocculated primary nanoparticles, with air pores formed between the primary nanoparticles. Unlike in the prior art, the porous manganese oxide nanoparticles of the disclosure have 6 nm or less MnO.sub.2 primary nanoparticles and Mn.sub.3O.sub.4 primary nanoparticles uniformly mixed and flocculated, exhibiting a 16 times higher specific surface area as compared with the conventional manganese oxide particles and superior storage characteristics and stability.

In a method for recovering an active metal of a lithium secondary battery, a cathode active material mixture is prepared from a cathode of a lithium secondary battery. A first reductive process using a first reductive reaction gas and a second reductive process using a second reductive reaction gas that has a higher reaction source concentration than that of the first reductive reaction gas are performed sequentially and continuously to convert the cathode active material mixture into a preliminary precursor mixture. A lithium precursor is recovered from the preliminary precursor mixture. A lithium recovery ratio may be increased by a stepwise reduction while preventing an increase of heating value.

A reducing agent for use in production of a product gas containing carbon monoxide, the reducing agent being brought into contact with a raw material gas containing carbon dioxide to reduce the carbon dioxide to produce the product gas; the reducing agent containing an oxygen carrier having oxygen ionic conductivity, and a basic oxide supported on the oxygen carrier. In addition, the basic oxide preferably contains at least one selected from the group consisting of lithium (Li), sodium (Na), potassium (K), magnesium (Mg), manganese (Mn), cobalt (Co), strontium (Sr), and rubidium (Rb). The reducing agent has a high conversion efficiency of carbon dioxide to carbon monoxide, and can be used, for example, in a chemical looping method, and a method for producing a gas using such a reducing agent.