Abstract: A novel catalyst for catalytic reduction of nitrogen oxide using a hydrocarbon as a reducing agent is provided, which comprises (a) at least an element of the platinum group selected from the group consisting of platinum, iridium, rhodium and ruthenium and (b) gold, and which may further comprises (c) at least a metallic oxide selected from the group consisting of cerium oxide, lanthanum oxide, neodymium oxide, germanium oxide and gallium oxide.

Abstract: A catalyst for catalytic reduction of nitrogen oxide using at least one reducing agent selected from the group consisting of a hydrocarbon and an oxygen-containing organic compound is described, which includes an oxide represented by formula (V):A.sup.5.sub.x B.sup.3.sub.3-x C.sup.4.sub.3 O.sub.7 (V)wherein A.sup.5 represents at least one element selected from the group consisting of La, Y, Ce, Pr, Nd, Sm, Eu, and Gd; B.sup.3 represents at least one element selected from the group consisting of Ba, Sr, Ca, Mg, Pb, Zn, and Ag; C.sup.4 represents at least one element selected from the group consisting of Mn, Co, Fe, Ni, Cr, Cu, V, Mo, W, Ti, Zr, Nb, Pd, Rh, Ru, and Pt; and x is a number of from 0 to 1, supported on a solid acid carrier.

Abstract: Apparatus for sealing a magnetic shaft includes a magnetic housing having a throughbore with a stepped enlargement at one end, a pair of annular disk-shaped yokes spaced apart by an axially magnetized permanent magnet positioned in the stepped enlargement and surrounding the shaft, and magnetic fluid in the gaps between the yokes and the shaft. The outside diameter of one yoke is spaced from the magnetic housing and is smaller than the outside diameter of the other yoke, while the larger yoke abuts the magnetic housing at its outside diameter. A plastic, non-magnetic member can separate the smaller diameter yoke from the magnetic housing.

Abstract: A device for inscribing additional informations on microfilms of a construction, wherein informations already recorded on microfilms are projected on an image screen by means of an enlarging and projecting device, additional informations to be entered on this microfilm are written in on the projected enlarged information images on the screen by a pen through guide means which moves on the projected image on the screen, the additional informations thus written-in on an appropriate portion on the projected image on the screen are reduced by a scale reducing means interlinked with the guide means and which reduces the movement of the guide means, and the thus reduced additional informations are then inscribed on the microfilm by means of write-in needle attached to the scale-reducing means.