Rare earth compound particles are prepared by a step of heating an aqueous solution containing rare earth metal ions and urea to form a rare earth compound by a reaction of a hydrolysis product of urea, and the rare earth metal ions. In the heating step, heating the aqueous solution into which an acetylene glycol-ethylene oxide adduct is added.

A cerium oxide nanoparticle whose surface is covered with a vinyl polymer has a heterocyclic amine skeleton such as piperazine, pyridine, imidazole, or carbazole or with a polyamide having a heterocyclic amine skeleton such as piperazine, pyridine, imidazole, or carbazole; and a decomposition method of a nucleic acid or a polypeptide by using the cerium oxide nanoparticle.

A cerium oxide nanoparticle whose surface is covered with a vinyl polymer has a heterocyclic amine skeleton such as piperazine, pyridine, imidazole, or carbazole or with a polyamide having a heterocyclic amine skeleton such as piperazine, pyridine, imidazole, or carbazole; and a decomposition method of a nucleic acid or a polypeptide by using the cerium oxide nanoparticle.

The present disclosure provides for compositions, methods of making compositions, and methods of using the composition. In an aspect, the composition can be a reactive material that can be used to split a gas such as water or carbon dioxide.

The present disclosure provides for compositions, methods of making compositions, and methods of using the composition. In an aspect, the composition can be a reactive material that can be used to split a gas such as water or carbon dioxide.

Disclosed are a composite oxide which is capable of maintaining a large volume of pores even used in a high temperature environment, and which has excellent heat resistance and catalytic activity, as well as a method for producing the composite oxide and a catalyst for exhaust gas purification employing the composite oxide. The composite oxide contains cerium and at least one element selected from aluminum, silicon, or rare earth metals other than cerium and including yttrium, at a mass ratio of 85:15 to 99:1 in terms oxides, and has a property of exhibiting a not less than 0.30 cm.sup.3/g, preferably not less than 0.40 cm.sup.3/g volume of pores with a diameter of not larger than 200 nm, after calcination at 900° C. for 5 hours, and is suitable for a co-catalyst in a catalyst for vehicle exhaust gas purification.

The present invention relates to a process for purifying and concentrating rare earths contained in phosphogypsum, characterised in that it comprises the following steps of: from a phosphogypsum, a) Leaching the phosphogypsum with a solution of one or more strong acid(s) selected from among: sulphuric acid, nitric acid and hydrochloric acid, in order to obtain a leaching mixture comprising a liquid phase formed by a leaching solution containing rare earths from the phosphogypsum and the leaching acid, and a solid phase comprising the phosphogypsum, b) Adding, to the phosphogypsum, an oxidising agent to promote passage of the rare earths from the phosphogypsum into the leaching solution, and/or a reducing agent to reduce solubility of mineral impurities contained in the leaching solution in order to allow their passage from the leaching solution into the solid phase, c) Separating the liquid phase enriched in rare earths and depleted in mineral impurities, and the solid phase enriched in mineral impurities.

The present invention relates to a process for purifying and concentrating rare earths contained in phosphogypsum, characterised in that it comprises the following steps of: from a phosphogypsum, a) Leaching the phosphogypsum with a solution of one or more strong acid(s) selected from among: sulphuric acid, nitric acid and hydrochloric acid, in order to obtain a leaching mixture comprising a liquid phase formed by a leaching solution containing rare earths from the phosphogypsum and the leaching acid, and a solid phase comprising the phosphogypsum, b) Adding, to the phosphogypsum, an oxidising agent to promote passage of the rare earths from the phosphogypsum into the leaching solution, and/or a reducing agent to reduce solubility of mineral impurities contained in the leaching solution in order to allow their passage from the leaching solution into the solid phase, c) Separating the liquid phase enriched in rare earths and depleted in mineral impurities, and the solid phase enriched in mineral impurities.

A method of preparing a polishing composition includes forming a dispersion solution containing ceria particles, and irradiating ultraviolet (UV) light onto the dispersion solution.

Processes for making lightweight armor, hardened casts, hardened parts, nonstructural reinforced hardened casts, structural shrapnel-resistant blocks, attachable hardened surfaces, and for hardening surfaces utilize rare earth material nanoparticles including metal anhydride nanoparticles that are refined under supercritical conditions.