Abstract: In a GaAs epitaxial wafer including, for example, two epitaxial layers having high and low carrier concentrations, the carrier concentration of the low carrier concentration layer is liable to greatly vary, so that wafers suitable for FETs and Schottky barrier diodes operated at UHF and SHF are produced at only a low yield. This drawback is eliminated by adjusting the heating temperature of GaAs substrate to 690.degree. to 730.degree. C. during the growth of the low carrier concentration layer.

Abstract: An electrophotographic photoreceptor according to this invention has a photosensitive layer in which a photoconductive substance with the following general formula (I): ##STR1## wherein X is selected from the group consisting of hydrogen atom, lower alkyl group, lower alkoxy group, halogen atom and cyano group;Y is phenylene or naphthylene group;Z.sub.1 and Z.sub.2 are independently the divalent group represented by the following formula: ##STR2## wherein A is a divalent group derived from the aromatic hydrocarbon or heterocyclic compound including one or more nitrogen atoms in the ring; andn is 1 or 2, is incorporated.

Abstract: A hydrogenation catalyst for desulfurization and removal of heavy metals, comprises (a) at least one metal component selected from metals of Groups VI B and VIII of the Periodic Table, as a catalytically active component, and (2) a porous activated alumina carrier obtained by shaping a mixture of carbon black and a powder of activated alumina or a precursor of activated alumina, drying the shaped mixture and firing it in an oxygen-containing gas stream to burn off the carbon black.

Abstract: A deoxidizer comprises ferrous carbonate having a specific surface area of at least 20 m.sup.2 /g. The ferrous carbonate can be combined with a mixture of a reduced iron powder and a metal halide; or an alkli metal hydroxide and/or an alkline earth metal hydroxide or calcium oxide and/or ettringite. The deoxidizer is used for the deoxidation of a package so as to substitute oxygen by carbon dioxide.