Abstract: In an oxygen sensor of the type having an oxygen ion conductive tube of solid electrolyte, a ceramic heater disposed within the oxygen ion conductive tube for heating the same is in the form of a quadrangular prism or a bar of a rectangular cross section. The ceramic heater is formed by piling up ceramic green sheets with metallic thick-film patterns for heat generating resistors interposed between adjacent two of the ceramic green sheets. The ceramic heater is so shaped as to satisfy the relation of b/a=0.75.about.1 where "a" is the width and "b" is the thickness of the ceramic heater. The metallic thick films, which the metallic thick-film patterns are turned to by firing, are arranged so as to be parallel to the side surfaces opposed in the thickness direction of the ceramic heater.

Abstract: Disclosed is a compound represented by Formula (I): ##STR1## wherein Ar.sup.1, Ar.sup.2, n, A, B and Z are as defined in claims. Disclosed are also a process for preparing the compound and pharmaceutical compositions containing the compound.The compound has an antihistamic and antiallergic effect.

Abstract: A gas sensor has a ceramic substrate carrying a first ceramic layer formed thereon and a second ceramic layer formed on the first layer, the two layers having successive setbacks from one edge of the substrate so as to form a staircase-like edge structure, and a gas-sensitive layer is formed on the staircase-like edge portion of said substrate, height of said gas-sensitive layer above the substrate being less than the thickness of the first ceramic layer.

Abstract: A gas sensor has a heater circuit with a voltage-dividing element, and a voltage to energize the heater circuit is applied through a resistive lead wire element, while a sensor voltage to measure the resistance of a gas-sensitive element is branched from the heater circuit.

Abstract: There are disclosed a 4-alkoxy-1,3-dioxane-5-carbonitrile which is a novel compound represented by the formula ##STR1## wherein R represents a lower-alkyl group, and which is useful as an intermediate for the synthesis of Vitamin B.sub.1, and a process for preparing the novel compound by subjecting a 3-alkoxy-2-propenenitrile to reaction with a formaldehyde in the presence of an acid catalyst.

Abstract: A novel and industrial process for preparing cyclopentenone derivatives by heating C.sub.5 .about.C.sub.13 aliphatic acids having one substituent or intramolecular esters thereof in the presence of a solid acid catalyst in a good yield.