TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Particles: The metal-oxide nanoparticles and metal sulfide nanoparticles are doped with element chosen from zinc, titanium, zirconium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, rhodium, iridium, nickel, palladium, copper, silver, cadmium, aluminum, gallium, indium, silicon, germanium, tin, lead, lanthanoid and/or actinoids. 90 mol% or more of metal in the metal sulfide nanoparticles is zinc.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Particles: The metal-oxide nanoparticles or metal sulfide nanoparticles have number average particle diameter of 10 mm or less. The metal-oxide nanoparticles are formed by reacting organometallic compound (A) and hydroxyl group-containing basic compound in a solvent. The hydoxyl group-containing basic compound is chosen from lithium hydroxide, sodium hydroxide and potassium hydroxide. The organometallic compound (A) is chosen from zinc acetate, zinc-acetate dihydrate, acetyl acetones zinc hydrate, zinc benzoate, zinc citrate, zinc dibutyl dithiocarbamate, zinc diethyl dithiocarbamate, zinc formate, zinc dihydrate formate, zinc laurate and zinc salicylate trihydrate. The metal sulfide nanoparticles are formed by reacting organometallic compound (B) and sulfur compound. The organometallic compound (B) is chosen from zinc carboxylic-acid compound, zinc dithiocarbamic acid compound, zinc xanthogenic-acid compound, zinc acetylacetonato compound, manganese carboxylic acid compound, manganese acetylacetonato compound, copper carboxylic acid compound and copper dithiocarbamic acid compound. The sulfur compound is chosen from sulfide of alkali metal, sulfide of alkaline earth metal, sulfohydrate of alkali metal, hydrogen sulfide and thiourea.    TECHNOLOGY FOCUS - POLYMERS - Preferred Process: A terminal thiol group is introduced into the polymer using a processing agent after performing reversible addition-elimination chain-transfer polymerization. The processing agent is chosen from hydrogen-nitrogen-bond-containing compound, basic compound and reducing agent. Preferred Composition: The polymer is formed by polymerizing a monomer chosen from (meth)acrylic ester, (meth)acrylamide, (meth)acrylic acid, alkali metal salt of (meth)acrylic acid, styrene, alkali metal salt of p-styrene sulfonic acid, (vinyl benzyl) trimethyl ammonium chloride, acrylonitrile, vinyl pyrrolidone, vinyl pyridine, vinyl acetate, vinyl chloride, maleic acid anhydride and/or maleimide. The polymer has molecular weight distribution of 1.5 or less. EXAMPLE - N,N-dimethyl formamide (50 ml), azoisobutyronitrile (5.3 mg), 1-phenyl ethyl dithiobenzoate (42 mg) and acrylic acid (20 ml) were added to 4-lot flask, and reacted at 60degreesC. Then, the reaction solution was cooled to room temperature, and dimethylamine (10 ml) was added and stirred for 8 hours. The resulting reaction solution was poured into toluene and polymer was precipitated. The obtained polymer was poly(acrylic acid/N,N-dimethylacrylamide) having thiol group at the terminal, according to nuclear magnetic resonance. The obtained polymer had weight average molecular weight of 17200, number average molecular weight of 14300 and molecular weight distribution of 1.2. The conversion ratio of acrylic acid to acrylamide was 15%. The obtained polymer (0.5) was dissolved in 2-propanol solution (5 ml) of zinc oxide nanoparticles (formed using zinc-acetate dihydrate and 2-propanol) having number average particle diameter of 8.5 nm. The resulting solution was subjected to ultrasonic irradiation at room temperature for 1 hour, and hexane (10 ml) was added, to precipitate polymer-modified zinc oxide nanoparticles. The obtained polymer-modified zinc oxide nanoparticles were dissolved in methanol (1 ml) and re-precipitated by adding into hexane (10 ml). The obtained polymer-modified zinc oxide nanoparticles exhibited an emission spectrum in 510 nm wavelength. The transmission electron microscope (TEM) observation of the modified nanoparticles confirmed the absence of aggregation of modified zinc oxide nanoparticles.