Abstract: A wafer placement table includes a ceramic plate that has at least a wafer placement part at an upper surface thereof, a cooling plate that is joined to a lower surface of the ceramic plate and that has a refrigerant flow path, gas common paths that are provided above the refrigerant flow path, gas introduction paths that extend from a lower surface of the cooling plate to a corresponding one of the gas common paths, and a plurality of gas distribution paths, that are provided for the gas common paths. The gas distribution path that is disposed at an outermost periphery of the ceramic plate is provided at a position that does not overlap the refrigerant flow path in plan view.

Abstract: Electric resistance welded steel pipe excellent in weld zone quality suitable for oil country tubular goods and line pipe wherein steel plate forming the base metal of the electric resistance welded steel pipe has a predetermined chemical composition, the contents of Ca, O, S, Ce, La, and Al satisfy XCASO = ( Ca O + Ca S + 0.285 ? Ce + La O + 0.285 ? Ce + La S ) × ( Al Ca ) > 78 the oxide-based inclusions in the weld zone of the electric resistance welded steel pipe contains one or both of Ce and La, and the long axis/short axis of the oxide-based inclusions is 2.5 or less.

Abstract: Electric resistance welded steel pipe excellent in weld zone quality suitable for oil country tubular goods and line pipe wherein steel plate forming the base metal of the electric resistance welded steel pipe has a predetermined chemical composition, the contents of Ca, O, S, Ce, La, and Al satisfy XCASO = ( Ca O + Ca S + 0.285 ? Ce + La O + 0.285 ? Ce + La S ) × ( Al Ca ) > 78 the oxide-based inclusions in the weld zone of the electric resistance welded steel pipe contains one or both of Ce and La, and the long axis/short axis of the oxide-based inclusions is 2.5 or less.

Abstract: Disclosed herein is a method of sequentially and continuously determining the concentrations of carbon, hydrogen, and nitrogen in molten steel using a single apparatus. Disclosed also herein are a method and an apparatus for determining trace amounts of carbon in molten steel which are the specialized application of the principle used for the above-mentioned method.