The electrostatic chuck includes an insulating substrate having a placement surface on which a suction target object is placed and an opposite surface provided on an opposite side to the placement surface; and a gas hole penetrating from the opposite surface to the placement surface. The gas hole has a first hole portion extending from the opposite surface toward the placement surface, a second hole portion extending from the placement surface toward the opposite surface, and a third hole portion provided between the first hole portion and the second hole portion and formed to communicate the first hole portion and the second hole portion each other. The first hole portion is provided not to overlap with the second hole portion in a plan view.

A method for manufacturing a prefabricated concrete product is disclosed, in which method, a concrete slab with a recess at its upper surface is cast with slipform casting on a casting bed, and after the slipform casting of the slab the recess of the fresh cast slab is equipped with ducts, piping and/or wiring components, after which the recess is covered with concrete mass, and the concrete product is left to cure. The invention also relates to such a prefabricated concrete product.

A tapering assembly compresses a butt end of a barrier into a tapered end for enhanced installation. The barrier includes sheet rock panel. A plurality of rollers and at least one taper roller pass through a front end of a plate portion. The barrier passes through a predetermined distance between the taper roller and the plurality of rollers. The taper roller includes a gradient taper. The plurality of rollers guide the barrier against the taper roller. A rear end of the plate portion includes a bearing that enables the taper roller and plurality of rollers to pass through. A taper roller shaft extends from a rear end of the plate portion. A variable speed drill rotates the taper shaft to provide rotation and torque to the taper roller. The barrier butt end is tapered without causing damage to the barrier from the position and precision calibration of the rollers.

A placement member according to the present disclosure includes a base portion having a flat plate shape and a plurality of protruding portions on a main surface of the base portion. Each of the protruding portions includes a placement surface on which a to-be-inspected object or a to-be-treated object is placed. The placement surface includes a concave inner peripheral side curved surface and an outer peripheral side convex portion connected to the inner peripheral side curved surface.

Described herein is a system and method to produce a taper on a drywall board to facilitate taping and compounding where two boards abut. A groove is formed on the back side of a drywall board, resulting in a first gypsum-containing segment hingeably connected to a second gypsum-containing segment. A taper is created by rotating the segments until they meet, and then removing excess material.

Prefabricated floor element (1) having an elongated shape wherein a longitudinal direction (X), a transversal direction (Y), a height direction (Z), two end faces (11) which delimitate the element (1) in the longitudinal direction (X), two lateral faces (12) which delimitate the element (1) in the transversal direction (Y), a lower face (13) and an upper planar face (14) that delimitate the element (1) in the height direction (Z) are defined, which comprises transversal continuous upper grooves (15) on the upper planar face (14) or lateral grooves (26) on the lateral faces (24), the lateral grooves (26) extending from the lower tab (TS) to the upper planar face (24). The invention also relates to a structure comprising such prefabricated floor element (1) and further comprising a linear supporting element (LS) which supports one end of the prefabricated floor element.