Abstract: In a flat Panel solar collector adapted to be evacuable and vacuum-tight, at least one absorber is provided. At least one conduit is provided which is at least Partially thermally associated with the at least one absorber. A holding structure is provided comprising a perimetric frame. At least one first transparent wall is provided, the first transparent wall and the holding structure having a overlapping area. At least one side of the first transparent wall comprises at least partially at said overlapping area a metal coating forming at least one metallized area on the transparent wall. A first soft metal ribbon is provided sealing the junction between the first transparent wall and the holding structure and which is soldered to the holding structure and to the metallized area of the first transparent wall.

Abstract: A diaphragm system to center and hold at least one inner body within an outer body, which inner body and outer body extend in a first direction, has a plurality of washers positioned between an inner surface of the outer body and has a recess or aperture for receiving each of the inner bodies. The washers have an outer circumference provided with a surface contact portion for engaging an inner surface of the outer body, and each of the recesses has a surface contact portion for engaging an outer surface of the inner body with the contact portion for engaging the outer body and the contact portion for engaging each of the inner bodies having an angular extent up to 180°. The washers are mounted at different angular orientations perpendicular to the first direction regarding their contact portions, so that pressure is applied uniformly around each of the inner bodies.

Abstract: A bath composition for the electropolishing of a metal surface made of nonalloyed titanium is disclosed. The bath composition may comprise sulfuric acid of 2 to 40% by volume, hydrofluoric acid of 10 to 18% by volume and acetic acid of 42 to 62% by volume.