Abstract: A piezoelectric acoustic device capable of permitting an increase in area or space of an operation face section of an electronic equipment required for arranging parts for the electronic equipment, attaining small-sizing of an electronic equipment and minimizing intrusion of water and dust into a front air chamber through a drum. The piezoelectric acoustic device includes a piezoelectric vibrator including a metal vibrating plate and a piezoelectric ceramic element joined to the metal vibrating plate, a casing including a front side wall and a rear side wall arranged on both sides of the piezoelectric vibrator so as to define a space therebetween in which the piezoelectric vibrator is received, and a drum arranged on an outside of the front side wall so as to extend in a direction across the front side wall. The piezoelectric vibrator and front side wall are arranged so as to define a chamber therebetween and the drum is formed therein with a passage in a manner to communicate with the chamber.

Abstract: A piezoelectric acoustic device capable of keeping a substantial diameter of a metal vibrating plate from being reduced and preventing clogging of a damping cloth member. The piezoelectric acoustic device includes a piezoelectric vibrator including a metal vibrating plate and a piezoelectric ceramic element joined to the metal vibrating plate. The piezoelectric vibrator is arranged in a casing which is formed on an inner peripheral surface thereof with an inclined joint surface section of an annular shape which surrounds an outer peripheral portion of the metal vibrating plate. The piezoelectric acoustic device also includes a pressure-sensitive adhesive layer formed by coating a pressure-sensitive adhesive on the inclined joint surface section. The outer peripheral portion of the metal vibrating plate is joined through the pressure-sensitive adhesive layer to the inclined joint surface section.

Abstract: Novel substantially linear, or at least partially cross-linked, nitrogen-containing polymers having an aryleneimine or arylenether unit in the main chain with an amino group or a group derived from it being bonded as a pendant group to a nuclear carbon atom of the arylene group of the above unit. According to the number and type of the pendant groups, the polymers can have various useful properties such as thermal stability, hydrophilicity, oxidative reducibility, photosensitivity, color formability or the ability to form coordination bonds. Furthermore, the polymers have good solubility in aprotic polar organic solvents. Permselective membranes having good performance can be prepared from solutions of the polymers in these solvents.

Abstract: Novel aromatic polymers containing a nitrogen-containing ring group which comprises at least 30 mol% of a recurring unit of the formula ##STR1## Preferably,, the nitrogen-containing ring group ##STR2## is a benzimidazolone, benzimidazolthione, benzimidazole, quinoxalidinedione, benzotriazole, benzothiazolidine, benzothiadiazolidine-S-oxide, benzothiadiazolidine-S-dioxide, benzodithiadiazine, benzodiazophosphole-p-oxide, benzodiazophosphole, benzodiazosilole, or benzodiazoborole ring.These polymers are soluble in various polar solvents. They find a wide range of applications ascribable to these ring groups, for example, as thermally stable resins and permselective membranes. These polymers can be prepared by reacting substantially linear aromatic polymers comprising at least 30 mol% of a recurring unit of the formula ##STR3## with reagents capable of forming 5- or 6-membered nitrogen-containing rings.

Abstract: Novel aromatic imine polymers containing as at least a part of its entire recurring units an aromatic imino group ##STR1## wherein .phi. is an aromatic ring group having a valence of at least two and has at least one electron-attracting group with respect to the group ##STR2## and R.sub.1 is a hydrogen atom or a non-aromatic hydrocarbon residue having a valence of at least 1. These polymers find a wide variety of applications by utilizing their thermal stability and various other desirable properties such as reducibility or photosensitivity. The polymers are prepared by reacting specific aromatic dihalogen compound with specific difunctional amino-containing compounds in an inert organic solvent in the presence of an acid acceptor. Copolymers can be obtained by carrying out the reaction using specific difunctional comonomers.

Abstract: This invention provides a novel permselective polymeric membrane excellent in permselectivity which allows permeation of water in an aqueous solution at a high rate but is highly preventive of permeation of solutes, and a process for the preparation of such permselective membrane, said polymeric membrane consisting essentially of a linear polymer containing N-aryl-substituted-benzimidazole units as the main-chain-constituting units.