Abstract: Two pipe-construction houses of a shed-roofed type, facing each other at their ridge sides with a gap provided between the ridges, are coupled with girders to make an integrated construction. The sides are covered with rollable ventilative sheets, and its roof is made of a soft plastic film span on a pipe-construction roof frame above a hard plastic sheet spread along the central part in the longitudinal direction of the roof. Cultivation beds of rust-prevention-coated thin steel sheet are hung on bed bearing fittings of a pipe structure. Nutrient solution is fed by an air lift pump under control by electric conductance thereof.

Abstract: This invention relates to a soilless culture device comprising a culture solution tank and a cultivation vessel having a flow path for the solution fed from the solution tank. Where the solution flow path, or cultivation vessel is substantially long, the flow path is arranged to turn at an intermediate point so that it is divided into two portions, forward and return, disposed in parallel relation and allowed to communicate with each other at any desired point by means of a short-circuiting path. Equalization of the culture solution between the supply side and the discharge side can be thus attained. A level regulating pipe adapted to regulate the solution level in the cultivation vessel is provided between the solution tank and the cultivation vessel. A cup for adjusting the solution level is removably mounted in the opening of the level regulating pipe.

Abstract: Electrolysis is employed for raising or reducing pH of culture solution. Electrolyte contained in a vessel having at least one ion exchange membrane as a wall is provided so as to confront the culture solution, with the ion exchange membrane lying therebetween. Electrodes are provided both in the electrolyte and the culture solution. With these electrodes the electrolysis is carried out through the ion exchange membrane. Thus formed alkali or acid changes the pH of the culture solution. By controlling the time or supplied current for the electrolysis, required pH can be accurately obtained.

Abstract: In removing nitrogen oxide from a gas containing it, the gas is passed through a region where at least one of calcium sulfate and calcium hydroxide coexists with powerful oxidation agents such as sodium chlorite, potassium permanganate, etc. thereby removing the nitrogen oxide, mainly nitrogen monoxide, from the gas. This method is very effective in purifying exhaust gases resulting from burning operations, since 80 to 90% or more of the nitrogen oxide contained in the exhaust gases is nitrogen monoxide. In addition, this method is also effective in purifying indoor air.

Abstract: In removing nitrogen oxide from a gas containing it, the gas is passed through a region where at least one of calcium sulfate and calcium hydroxide coexists with powerful oxidation agents such as sodium chlorite, potassium permanganate, etc. thereby removing the nitrogen oxide, mainly nitrogen monoxide, from the gas. This method is very effective in purifying exhaust gases resulting from burning operations, since 80 to 90% or more of the nitrogen oxide contained in the exhaust gases is nitrogen monoxide. In addition, this method is also effective in purifying indoor air.