A layered double hydroxide is represented by the following formula (I): Ni.sup.2+.sub.1−(x+y+z)Fe.sup.3+.sub.xV.sup.3+.sub.yCo.sup.3+.sub.z(OH).sub.2A.sup.n−.sub.(x+y+z)/n.Math.mH.sub.2O . . . (I). In one embodiment, in the formula (I), (x+y+z) is from 0.2 to 0.5, “x” represents more than 0 and 0.3 or less, “y” represents from 0.04 to 0.49, and “z” represents more than 0 and 0.2 or less.

A method for making an iron-based oxide magnetic powder includes adding raw material solution containing trivalent iron ions, or trivalent iron ions and ions of a metal element that partially substitutes Fe sites, and an alkaline aqueous solution for neutralizing the raw material solution to a reaction system to adjust the pH of the reaction system to 1.0 or higher and 3.0 or lower. Hydroxycarboxylic acid is added to the obtained reaction solution and thereafter the pH of the reaction system is neutralized to 7.0 or higher and 10.0 or lower. The obtained precipitate of a substituent metal element-containing iron oxyhydroxide is coated with silicon oxide and then heated, whereby an iron-based oxide magnetic powder is obtained with a reduced content of fine and coarse particles, a particle shape close to a perfect sphere, and particles of ε-iron oxide in which Fe sites are partially substituted by other metal elements.

A gas-sensitive material, a preparation method therefore and an application thereof, and a gas sensor using the gas-sensitive material are provided. The gas-sensitive material is a carbon material-metal oxide composite nanomaterial formed by compounding a carbon material and metal oxides. The content of the carbon material is 0.5˜20 wt. % and the content of the metal oxides is 80˜99.5 wt. %; the metal oxides contain tungsten oxide and one or more selected from tin oxide, iron oxide, titanium oxide, copper oxide, molybdenum oxide, and zinc oxide; the metal oxides are formed on the carbon material in the form of nanowires, and the nanowires are tungsten oxide-doped nanowires. The gas-sensitive material has reduced resistance, is capable of responding to various gases at a reduced working temperature.

A sensing material for detecting hydrogen sulfide capable of detecting hydrogen sulfide even having a low concentration, a hydrogen sulfide-sensitive layer containing the sensing material for detecting hydrogen sulfide, and a metal oxide semiconductor-type gas sensor having the hydrogen sulfide-sensitive layer are provided. The sensing material for detecting hydrogen sulfide includes CuFe.sub.2O.sub.4-type complex oxide (W). The CuFe.sub.2O.sub.4-type complex oxide (W) contains, as a main component (W1), 35.0 to 49.5 mol % of iron oxide in terms of Fe.sub.2O.sub.3 and 50.5 to 65 mol % of copper oxide in terms of CuO, and an average particle diameter of particles is 3 μm or less.

An immuno-therapy for treatment of a tumor is provided. An effective dose of a composition containing a low dose of superparamagnetic iron oxide nanoparticle is administered to a tumor. Once the composition has been administered, it is recommended to avoid any means that would cause direct cytotoxic effects to the cancer cells and to normal/healthy tissue. The combination of composition-administered cancer cells with the avoidance of direct cytotoxic effects has been shown to be successful to inhibit the growth of the cancer cells or result in aptosis of the cancer cells. Additional dose(s) can be administered when it is determined that: (i) the tumor starts to grow and/or (ii) the remaining composition falls below a threshold. The immuno-therapy method is a safe, clinically applicable, ready-to-use theranostic approach for cancer patients who are unable to start chemoradiotherapy in a timely manner, i.e. an effective interim or adjunctive treatment for patients.

The present invention provides an electrocatalytic material and a method for making an electrocatalytic material. There is also provided an electrocatalytic material comprising amorphous metal or mixed metal oxides. There is also provided methods of forming an electrocatalyst, comprising an amorphous metal oxide film.

A radio wave absorber provided with a radio wave absorbing film formed on a substrate, the radio wave absorber being capable of absorbing radio waves over a broad frequency band and exhibiting superior radio wave absorbing properties even with a radio wave absorbing film thinner than 1 mm. A film forming paste suitable for forming a radio wave absorbing film that is provided in the radio wave absorber. In a radio wave absorber provided with a radio wave absorbing film formed on a substrate, a particular epsilon-type iron oxide is employed in the radio wave absorbing film and relative permittivity of the radio wave absorbing film is set to 6.5 to 65.

A method for formation of scorodite and for stabilization of arsenic by formation of scorodite, comprising using sodium hypochlorite as an oxidizing agent. The method comprises producing sodium hypochlorite having a concentration in a range between 1 and 3 w/w % using a diaphragm-less electrolytic cell operating with a sodium salt solution having a salt concentration in a range between 2 and 10 w/w %; diluting a sodium hypochlorite solution to less than 1 w/w % in an arsenic solution at an oxydo reduction potential in a range between 900 and 1100 mV (Pt, AgCl reference) and a pH comprised in range between 0.5 and 2.0; contacting a resulting oxidized arsenic with a ferric salt; and raising the pH to 5.

An e-type iron-based oxide magnetic particle powder has narrow particle size distribution and has a low content of fine particles which do not contribute to magnetic recording characteristics. As a result, a narrow coercive force distribution is achieved and the powder is suitable for increasing recording density of a magnetic recording medium. The powder containing substituting metal elements can be obtained by: adding an alkali to an aqueous solution containing trivalent iron ions and ions of the metals for partially substituting Fe sites to neutralize the aqueous solution to a pH of 1.5 to 2.5; then adding a hydroxycarboxylic acid; further adding the alkali to neutralize the aqueous solution to a pH of 8.0 to 9.0; washing with water a precipitation of an iron oxyhydroxide containing the substituting metal elements produced; and coating the iron oxyhydroxide containing the substituting metal elements with a silicon oxide and heating the resultant.

Provided is hexagonal strontium ferrite powder for magnetic recording, in which an activation volume is 800 to 1,500 nm.sup.3, a content of rare earth atom with respect to 100 atom % of iron atom is 0.5 to 5.0 atom %, and a rare earth atom surface portion uneven distribution is provided.