Abstract: An electroacoustic transducer comprises: a lower electrode; an upper electrode including an oscillation portion and a support portion for supporting the oscillation portion at least at a part of a periphery of the oscillation portion; and an insulating layer for insulating the lower electrode from the upper electrode, wherein the upper electrode has an up and down in the oscillation portion and/or in the support portion to provide a cavity between the upper electrode and the lower electrode.

Abstract: A concrete block having comparatively light weight and capable of being manufactured easily and used in various fields of application; a block joint for the concrete blocks, capable of carrying out the arrangement of the concrete blocks simply and retaining the arranged concrete blocks in good order; and a structure made by using the concrete blocks and the block joints.

Abstract: A reaction vessel and method of preventing evaporation employing a vessel body, a cap closing an open end of the vessel body and a piston head movable within the volume defined by the vessel body. A fluid to be reacted is introduced into the vessel body. An inner passage gradually converges toward the closed end from the open end so that the piston head, which is compressible, increasingly deforms under compression as it displaces further away from the open end. The piston head is moved tip a relative position relative to the closed end so that it sealingly engages the wall of the vessel and is positioned adjacent the upper surface of the fluid. In this position, the fluid may be heated to promote the reaction and evaporation is prevented by the piston head being adjacent the upper surface of the fluid and sealingly engaging the vessel wall.

Abstract: A plurality of open-top sample tubes, each containing a simple liquid containing cells to be treated, are removably mounted on a disklike sample carrier which is rotatable about a vertical axis for centrifuging the samples. Disposed above the sample carrier are a set of fixed reagent supply nozzles for dropping a desired reagent or reagents into the sample tubes and at least one supply-discharge nozzle movable into and out of the successive sample tubes. A hydropneumatic circuit is coupled to the supply-discharge nozzle for intimately intermingling the samples and the reagents and for rinsing the supply-discharge nozzle and other required parts. In an alternate embodiment a single supply-discharge nozzle is employed for reagent supply into the sample tubes, for intermingling the samples and the reagents, and for rinsing.

Abstract: A method for removing an amorphous selenium-containing photosensitive layer from an electrophotographic photoreceptor including an electroconductive metallic substrate having thereon the amorphous selenium-containing photo-sensitive layer using a method in which the combination of substrate and selenium-containing photosensitive layer is treated with an aqueous solution of sodium sulfide or sodium thiourea.

Abstract: A tubular container for centrifugal separation suited for easy separation of a relatively small amount of the phase having an intermediate specific gravity from the heaviest and lightest phases. The container has a first section defining a bottom chamber of a certain volume for containing therein the heaviest phase, a second section contiguous to the first section and defining an intermediate chamber for containing therein the phase having the intermediate specific gravity, and a third section contiguous to the second section and defining an upper chamber for containing therein the lightest phase. The diameter of said second section is smaller than the diameters of the first and third sections.

Abstract: A compound capable of forming a color on contact with an electron accepting compound and useful as a chromogenic material for recording members represented by the general formula (I) ##STR1## wherein A represents an oxygen atom or a group capable of forming a lactam ring with benzen ring D; Y represents a hydrogen atom or a functional group (such as a halogen atom or a nitro group); and when A is an oxygen atom, R represents an amino, i.e., unsubstituted, group or a substituted amino group; R.sub.1 and R.sub.3, which may be the same or different, each represents a hydrogen atom, a lower alkyl group, a nitro group, an amino group, or a substituted amino group; and R.sub.2 represents a hydrogen atom or a lower alkyl group; wherein R.sub.1 and R.sub.2 or R.sub.2 and R.sub.3 may combine with benzene ring C to form a nitrogen-containing heterocyclic ring condensed therewith; and when A is a group capable of forming a lactam ring with benzene ring D, R represents ##STR2## R.sub.2 represents ##STR3## R.sub.4 ', R.

Abstract: A process for the preparation of 4-amino-3-methyl-N-substituted or unsubstituted alkylanilines comprising acylating and/or sulfonylating 4-amino-3-methyl-nitro-benzene having the formula (I) ##STR1## with an acylation or sulfonylation agent to obtain a compound having the general formula (II) ##STR2## wherein R.sub.1 represents a hydrogen atom or an acyl group, R.sub.2 represents an acyl group or a sulfonyl group, or R.sub.1 and R.sub.2 can combine as a difunctional acyl group; reducing the nitro group of the compound having the general formula (II) with hydrogen in the presence of a metal hydrogenation catalyst to obtain a compound having the general formula (III) ##STR3## wherein R.sub.1 and R.sub.2 are as above defined; alkylating the amino group of the compound having the general formula (III) with an alkylation agent selected from the group consisting of an alkyl halide, a substituted alkyl halide and an alkylene oxide to obtain a compound having the general formula (IV) ##STR4## wherein R.sub.1 and R.

Abstract: A color developer is disclosed which, when contacted with a color former, is capable of forming a distinct color, the color developer comprising a metallic compound of an aromatic carboxylic acid. Suitable metals are, for example, those of the following groups of the Periodic Table: Ib, IIa, IIIb, IVb, VIa, VIIa and VIII. A recording sheet employing the color developer is also disclosed.