Abstract: This invention relates to an imaging element, such as a photographic or photothermographic element comprising a silver halide emulsion layer, wherein the element also comprises a compound of Structure I: wherein the substituents are as defined in the specification.

Abstract: A photothermographic material comprising at least (a) a photosensitive silver halide, (b) a reducible silver salt, (c) a reducing compound represented by the following formula (1) or (2), (d) a binder and (e) a coupler compound on the same side of a support: 1

Abstract: Thermographic and photothermographic materials comprise a barrier layer to provide physical protection and to prevent migration of diffusible imaging components and by-products resulting from high temperature imaging and/or development. The barrier layer comprises a film-forming acrylic or methacrylic acid ester or amide polymer(s) that has a molecular weight of at least 8000 g/mole and comprises hydroxy functionality in from about 15 to 100 mole % of the acrylic or methacrylic acid ester or amide recurring units. This barrier layer is capable of retarding diffusion of mobile chemicals such as fatty carboxylic acids, developers, and toners. This barrier layer can also include at least one other film-forming polymer to provide a clear and scratch-resistant surface.

Abstract: A radiographic film material is described including a transparent film support having first and second major surfaces coated with a subbing layer, optionally overcoated with an antihalation undercoat. Coated adjacent on each side of the film support is a light-sensitive silver halide emulsion overcoated with a protective antistress layer. The emulsion layer has chemically and spectrally sensitized {111} tabular hexagonal grains or crystals, having silver iodide in an amount of at most 3 mole %, based on silver, covering at least 50% of the total projective surface of all grains, having an average grain thickness of less than 0.30 &mgr;m. The antistress layer, or the optional antihalation undercoat or both includes a N-amino mercapto-triazole compound containing one or more alkali soluble group(s). A radiographic screen/film combination is also described including the film material.

Abstract: A radiographic film material has been provided, comprising a transparent film support having first and second major surfaces coated, apart from a subbing layer and, optionally, a non-light-sensitive hydrophilic layer thereupon, with at least one light-sensitive silver halide emulsion layer overcoated with a protective antistress layer, said emulsion layer(s) having chemically and spectrally sensitized {111} tabular hexagonal core-shell emulsion grains or crystals in an amount of at least 50% of the total projective grain surface of all grains, said grains being composed of a silver bromide core and a silver bromoiodide shell having an average amount over the whole crystal volume of more than 90 mole % of silver bromide, said grains further having a mean equivalent volume diameter of from 0.3 &mgr;m up to 1.0 &mgr;m and an average grain thickness of less than 0.

Abstract: A black-and-white silver halide photographic film material, particularly suitable for use in radiography, has been disclosed, said material comprising a transparent film support having first and second major surfaces coated with a subbing layer, further coated adjacent thereto on one side (for a single-side coated material) or on both sides (for a duplitized material) of said film support and overcoated with a protective antistress layer, a light-sensitive silver halide emulsion layer having chemically and spectrally sensitized {111} tabular hexagonal grains, accounting for at least 50% of the total projective surface of all grains, wherein said film material is coated with a low amount of silver and wherein said protective antistress layer(s)and/or another hydrophilic non-light-sensitive layer comprise(s) a compound according to general formula (I) in an amount of at least 0.5 mmole per mole of coated silver halide, as claimed.

Abstract: The present invention relates to homopolymer and copolymer waxes which have been prepared by polymerization using metallocene compounds in the presence of hydrogen and have a melt viscosity of less then 100 mPas, measured at 170° C. As a result of their high thermal stabillty, these waxes display neither discoloration nor crosslinking reactions and are vary well suited for use in toners, for plastics processing, for masterbatches, for printing inks, surface coatings and melt adhesives.

Abstract: An object of the present invention is to provide an electrostatic image developing toner having good charge properties, low-temperature fixing properties, offset resistance and blocking resistance as well as good resistance against sticking to a heated roll and wax dispersibility and a novel urethane-modified polyester resin used for the toner.

Abstract: Thermographic or photothermographic image recording elements comprising (a) a reducible silver salt, (b) a reducing agent, (c) a binder, (d) a specific phthalazine derivative and (e) an organic acid compound experience a minimized drop of image density when stored under warm humid conditions.

Abstract: A process for producing a photothermographic recording material having a support and a photo-addressable thermally developable element containing photosensitive silver halide in catalytic association with a substantially light-insensitive silver salt of an organic carboxylic acid, an organic reducing agent for the substantially light-insensitive silver salt of an organic carboxylic acid in thermal working relationship therewith and a binder including a water-soluble binder, a water-dispersible binder or a mixture of a water-soluble binder and a water-dispersible binder, comprising the steps of: (i) producing an aqueous dispersion or aqueous dispersions containing photosensitive silver halide, a substantially light-insensitive silver salt of an organic carboxylic acid, an organic reducing agent for the substantially light-insensitive silver salt of an organic carboxylic acid and a binder including a water-soluble binder, a water-dispersible binder or a mixture of a water-soluble binder and a water-dispersible

Abstract: The invention provides a photothermographic material comprising a photosensitive silver halide, an organic silver salt, a reducing agent, and a binder on a support. A layer containing the organic silver salt has been formed by using a solid particle dispersion of the organic silver salt and a polymer latex as a main binder, preparing a coating solution of the salt and the binder in an aqueous solvent, and coating the solution, followed by drying. Coating operation is easy, and coating surface quality and photographic properties are improved.

Abstract: A process for the preparation of branched thermoplastic resins comprising: heating a mixture of an unsaturated resin, a free radical initiator, and a stable free radical agent; adding to the heated mixture at least on polymerizable monomer; and cooling the mixture, wherein the resulting product is a branched thermoplastic resin with arms or branches comprised of polymerized monomer with substantially uniform length and narrow polydispersity.

Abstract: A silver halide photographic element has a silver halide emulsion layer primarily containing tabular silver halide grains and a hydrophilic colloid layer, either of which contains a pigment with a maximum absorption wavelength of 570-650 nm dispersed in lipophilic droplets of a high-boiling organic solvent. The photographic element has a high sensitivity and high silver covering power, and is improved in the transmission and reflection blackness of image silver and staining of fluorescent intensifying screens.

Abstract: A transfer material colored to a predetermined color is used when images are formed on a transfer material for use in thermal transfer comprising a substrate and a dye receiving layer by a thermal transfer process.When images are formed by an optional image forming method such as silver salt photographic process, ink jet process or thermal transfer process, a transfer material having sepia tone is used in each of the image forming processes thereby forming sepia tone images. Images having unique appearance can be formed easily upon forming images by a thermal transfer process. Images of sepia tone can be formed safely and conveniently.

Abstract: A transfer material colored to a predetermined color is used when images are formed on a transfer material for use in thermal transfer comprising a substrate and a dye receiving layer by a thermal transfer process.When images are formed by an optional image forming method such as silver salt photographic process, ink jet process or thermal transfer process, a transfer material having sepia tone is used in each of the image forming processes thereby forming sepia tone images. Images having unique appearance can be formed easily upon forming images by a thermal transfer process. Images of sepia tone can be formed safely and conveniently.

Abstract: A radiographic element is disclosed containing in a high bromide tabular grain emulsion layer a 5-mercaptotetrazole to increase covering power. The 5-mercaptotetrazole is additionally capable of increasing imaging speed and producing colder image tones when provided with a phenyl substituent in the 1 ring position, which phenyl substituent is in turn substituted in its para position with a substituent satisfying the formula R(OCH.sub.2 CH.sub.2).sub.n O-- wherein n is an integer of from zero to 5; when n is 1 to 5, R is hydrogen, methyl or ethyl; and, when n is zero, R is methyl.

Abstract: A black-and-white, negative-acting, silver halide emulsion is described which gives improved image tone when used in a photographic element. The toning agents are based on dithio-substituted compounds having the following general structures: ##STR1## where R.sub.1 and R.sub.2, independently, are selected from the group consisting of alkyl, aryl and heterocyclic groups, or R.sub.1 and R.sub.2 together complete a ring;n and m are integers from 1 to 5; Y is a hydrogen; R.sub.3 is a hydrogen or alkyl group;and X is selected from the group consisting of O, S, N--OH and N--N(R).sub.2, where R is a hydrogen or alkyl group.

Abstract: A silver halide photographic light-sensitive material is disclosed. The light-sensitive material comprises a transparent support having thereon a hydrophilic colloid layer comprising a silver halide emulsion layer and an electric conductive layer, in which the electric conductive layer contains colloidal particles of a kind of metal oxide and at least one layer of the hydrophilic colloid layer contains a leucocompound of a blue dye.

Abstract: A transfer material colored to a predetermined color is used when images are formed on a transfer material for use in thermal transfer comprising a substrate and a dye receiving layer by a thermal transfer process.When images are formed by an optional image forming method such as silver salt photographic process, ink jet process or thermal transfer process, a transfer material having sepia tone is used in each of the image forming processes thereby forming sepia tone images. Images having unique appearance can be formed easily upon forming images by a thermal transfer process. Images of sepia tone can be formed safely and conveniently.

Abstract: An image-forming film-screen system for medical diagnostic imaging is disclosed comprising a light-sensitive silver halide photographic film material in operative association with at least one intensifying screen comprising on a support a layer of a visible light emitting luminescent phosphor, the said film material comprising a support and on at least one side thereof a light-sensitive silver halide emulsion layer having spectrally sensitized tabular silver halide and a non-light-sensitive protective layer, wherein said protective layer contains a polymeric compound selected from the group consisting of gelatin, a synthetic, semi-synthetic or natural substitute for gelatin and latex (co)polymers, in an amount of at least 0.4 g per m.sup.2 ; characterized in that between a light-sensitive silver halide emulsion layer and said protective layer there is an intermediate layer comprising a blue colored pigment in dispersed form, having a solubility in isopropanol at 25.degree. C. of less than 10 mg per liter.

Abstract: A silver halide photographic light-sensitive material is disclosed. The light-sensitive material comprises comprising a support, having thereon, a silver halide emulsion layer and optionally a hydrophilic colloid layer, in which the silver halide emulsion layer comprises silver halide grains sensitized by a selenium compound or a tellurium compound, and a polysulfide compound, and at least one of the silver halide emulsion layer and the hydrophilic colloid layer contains a tabular particle of a silicate compound.

Abstract: A substantially non-photosensitive recording material comprising a thermosensitive element comprising a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith and a binder, on a support, characterized in that the thermosensitive element further comprises in reactive association with the light-insensitive organic silver salt and the organic reducing agent a 1,2,4-triazole compound with at least one of the nitrogen atoms having a hydrogen atom and none of the carbon atoms being part of a thione-group, said compound not being annulated with an aromatic ring system; and a thermal image recording process therefor.

Abstract: A toner resin composition and toner is provided, wherein said toner resin composition comprises a high molecular weight resin having a peak molecular weight of about 100,000-4,000,000, or a gel content of about 20% or more is blended with another resin comprising at least a low molecular weight component (having a peak molecular weight of about 3,000-50,000, making up about 60-95 wt % of the resin weight) and a high molecular weight component (having a peak molecular weight of about 100,000-4,000,000, making up about 5-40 wt % of another resin weight).

Abstract: Toning agents are provided for use in thermographic and photothermographic materials, either on their own or in combination with at least one other toning agent, with improved compatibility with hydrophobic media as shown by reduced crystallization and reduced diffusion through the material, which properties enabling an improved imaging performance to be achieved and in particular a more neutral image tone after storage.

Abstract: The present invention provides a method for reproducing continuous tone images by means of a thermal head. The method involves the image-wise heat transfer of a reducing agent from a donor element to a receiving layer of a receiving element. The receiving element contains a thermoreducible silver source such as e.g. silver behenate. The process of the present invention provides high density images with multiple intermediate density levels.

Abstract: A direct thermal recording process wherein a direct thermal recording material is heated dot-wise and said direct thermal recording material comprises on a substrate an imaging layer containing uniformly distributed in a film-forming polymeric binder (i) one or more substantially light-insensitive organic silver salts being no double salts, said silver salt(s) being in thermal working relationship with (ii) an organic reducing agent therefor, characterized in that said reducing agent is a benzene compound the benzene nucleus of which is substituted by no more than two hydroxy groups which are present in 3,4-position on said nucleus and have in the 1-position of said nucleus a substituent linked to said nucleus by means of a carbonyl group.

Abstract: Metal oxidizing agents (such as silver oxide or silver nitrate) are added to a solution of organic chemicals which comprise an unwanted level of organic reducing agents (either aqueous or organic solutions in which the metal oxidizing agent does not dissolve) and the metal oxidizing agent oxidizes at least some portion of said organic reducing agents. Because the metal oxidizing agent is insoluble in the solution, it is readily removed (e.g., by filtration or sedimentary techniques) to leave a solution with reduced amounts of reducing agents therein. This process is particularly useful for purifying phthalazine, behenic acid, and other toners, the component forming the counterion with silver ion in forming the light-insensitive silver source material and any other additives and raw materials which can be dissolved in a solvent medium in which the metal oxidizing agent is not highly soluble.

Abstract: A radiation thermally imageable, solid toner addressable article comprises a substrate having on at least one surface thereof a layer comprising a) a solid binder which can be converted to a supercooled liquid upon heating and subsequent cooling to room temperature, b) a dye which absorbs radiation (at the wavelength of the imaging device,, e.e., ultraviolet, visible [especially the red], and infrared wavelengths) and converts infrared radiation to thermal energy, and c) a fluorinated surfactant. A directly thermally addressable article does not require the radiation absorbable dye.

Abstract: Metal oxidizing agents (such as silver oxide or silver nitrate) are added to a solution of organic chemicals which comprise an unwanted level of organic reducing agents (either aqueous or organic solutions in which the metal oxidizing agent does not dissolve) and the metal oxidizing agent oxidizes at least some portion of said organic reducing agents. Because the metal oxidizing agent is insoluble in the solution, it is readily removed (e.g., by filtration or sedimentary techniques) to leave a solution with reduced amounts of reducing agents therein. This process is particularly useful for purifying phthalazine, behenic acid, and other toners, the component forming the counterion with silver ion in forming the light-insensitive silver source material and any other additives and raw materials which can be dissolved in a solvent medium in which the metal oxidizing agent is not highly soluble.

Abstract: A heat-sensitive coating composition, and heat-sensitive material for thermal imaging containing the heat sensitive composition. The composition comprises a color-forming amount of a finely divided, solid, colorless noble metal salt of an organic acid; a color-developing amount of an organic reducing agent which at thermal copy and printing temperatures is capable of a color-forming reaction with the noble metal salt; an image toning agent; and a carrier composition in which the noble metal salt, organic reducing agent, and toning agent are distributed. The carrier composition requires no organic solvents and comprises one or more substantially water-soluble polymeric carrier materials and a solubility-enhancing amount of a dispersing agent. A protective, clarifying, radiation-cured overcoat is provided. Methods of forming the heat-sensitive composition and the overcoat are also disclosed.

Abstract: A process for preparing images, particularly color proof prints, in which tacky and non-tacky areas are produced by imagewise exposure of a radiation-sensitive layer is described. The tacky areas are toned with a toner having a tackiness that can be increased by irradiation with actinic radiation.

Abstract: A low melt toner resin with low minimum fix temperature and wide fusing latitude contains a linear portion and a cross-linked portion containing high density cross-linked microgel particles, but substantially no low density cross-linked polymer. The resin may be formed by reactive melt mixing.

Abstract: A silver halide color photographic material comprising a support having thereon a cyan color-forming silver halide emulsion layer, a magenta color-forming silver halide emulsion layer, a yellow color-forming silver halide emulsion layer and at least one light-insensitive hydrophilic layer disposed farther from the support than any of these silver halide emulsion layers, in which the light-insensitive hydrophilic layer contains nonglobular fine-particle powder in a dispersion in an amount of at least 25% by weight based on the whole components therein, thereby ensuring excellent tone reproduction in the images and reduced dependence of image qualities upon the positions of viewing light sources. In addition, the color photographic material can provide images well-expressing a feeling of massiveness even in rapid photographic processing.

Abstract: The present invention provides an image receiving material comprising on a support an image receiving layer containing physical development nuclei characterised in that said image receiving material contains a nacreous pigment in said image receiving layer and/or in an optional layer between said support and said image receiving layer. Excellent contone images with an antique look can be obtained with such an image receiving material in a silver salt diffusion transfer process.

Abstract: Photothermographic compositions comprising a photographic silver halide, an organic silver salt, and a reducing agent for the organic silver salt, display improved stabilty in the presence of a compound having a nucleus of the formula: ##STR1## wherein: A represents any monovalent group for which the corresponding compound AH functions as a post-processing stabilizer,R.sup.1, R.sup.2, and R.sup.3, are independently hydrogen or methyl and with the proviso that R.sup.1 can represent an aryl group when R.sup.2 and R.sup.3 are hydrogen;R.sup.4 is hydrogen or lower alkyl of from 1 to 4 carbon atoms;R.sup.5 and R.sup.6 independently represent hydrogen, an alkyl group, a cycloalkyl group, an aryl group or R.sup.5 and R.sup.6 taken together with the carbon atom to which they are joined form a ring of 4 to 12 atoms;R.sup.7 and R.sup.8 are independently hydrogen or lower alkyl of 1 to 4 carbon atoms; andn is 0 or 1.

Abstract: A resin composition for toners with excellent characteristics is provided. The composition comprises, as principal components, a resin (A) containing carboxyl groups and a resin (B) containing glycidyl or .beta.-methylglycidyl groups, wherein the resin (A) is obtained by a reaction between a multivalent metal compound (m) and copolymer .alpha., said copolymer .alpha. being obtained from a styrene type monomer (a), a (meth)acrylic ester monomer (b), and a vinyl type monomer (c) containing carboxyl groups, and the resin (B) is copolymer .beta. obtained from a vinyl type monomer (d) containing glycidyl or .beta.-methylglycidyl groups and another vinyl type monomer (e).

Abstract: Herein disclosed is a binder for dry toners which comprises a copolymer resin obtained by reacting 10 to 50% by weight of a polyester resin which has free carboxyl groups, whose acid value ranges from 10 to 100 and whose number-average molecular weight ranges from 1,000 to 5,000 and 90 to 50% by weight of a mixture of a vinyl compound having a glycidyl group and the an another vinyl compound, wherein the amount of the vinyl compound having a glycidyl group corresponds to the number of the glycidyl groups equal to 0.25 to 1.5 time that of the carboxyl groups present in the polyester resin. The binder for dry toners is used in the electrophotography technique.

Abstract: Toner fusing members with improved properties are formed with an outer layer comprising a melamine-cured polyurethane coating composition. Such a polyurethane is formed by polycondensation of a diisocyanate, and a polysiloxane diol containing units of 2,2-bis(4-hydroxyphenyl) hexafluoropropane.

Abstract: A film unit for use in a silver salt diffusion transfer image-forming process is disclosed. The film unit includes a light-sensitive element, an alkaline treating element, and an image-receiving element. The light-sensitive element includes a light-sensitive silver halide emulsion layer containing a light-sensitive silver halide emulsion which contains silver bromoiodide or silver bromoiodochloride having a silver iodide content of 0.5 to 3.5 mol %, wherein silver bromoiodide having a silver iodide content of 1 to 5 mol % is formed on the surface of the silver halide grains in an amount of from 3 to 10% on a silver basis after completion of chemical sensitization. The alkaline treating element contains a water-soluble iodide in an amount of from 0.3 to 3.0 mM/l and tetrahydrophyrimidinethione in an amount of from 0.3 to 3.0 mM/l. The film unit allows rapid completion of transfer images without loss of photographing sensitivity.

Abstract: Provided is an image receiving material for silver complex diffusion transfer process which comprises a support, an image receiving layer provided on the support and an upper layer provided on the image receiving layer wherein physical development nuclei are distributed densely in the vicinity of the surface of the support and gradually diminishing towards the upper layer and a color toning agent is contained densely in the upper layer and gradually diminishing towards the surface of the support and the physical development nuclei and the color toning agent are thus mutually distributed. The image receiving material is produced by coating on a support a hydrophilic colloid coating solution for image receiving layer which contains physical development nuclei and contains substantially no color toning agent and thereon at least one hydrophilic colloid coating solution which contains at least one color toning agent and contains substantially no physical development nuclei.

Abstract: Undesired stain is minimized for pearlescent toners, adapted for toning elements having non-tacky and tacky areas that define an image, by including in the toner inert, substantially spherical particles having a particle size of approximately 0.3 to 42 microns and by including a slip-agent surface coating on at least the pearlescent pigment particles, and preferably also on the inert, substantially spherical particles.

Abstract: A process for the preparation of a color filter is described utilizing an exposure step of a light-sensitive material, imagewise exposing, toning and heat treating.

Abstract: An aqueous alkaline processing liquid suitable for use in the silver complex diffusion transfer reversal (DTR-) process, wherein said liquid contains one or more alkanolamines, the said alkanolamine(s) consisting of one or more tertiary alkanolamines in an amount in the range from 0.3 mol to 1.5 mol/l, and one or more secondary alkanolamines in an amount from 0 mol % to 5 mol % with respect to the amount of tertiary alkanolamine(s), and said liquid also contains a mixture of a silver image toning agent A being 1-phenyl-1H-tetrazole-5-thiol or a tautomer thereof and at least one other silver image toning agent B being a 1-phenyl-1H-tetrazole-5-thiol or a tautomer thereof, wherein the phenyl nucleus is substituted with halogen, the toning agent A and toning agent(s) B being present in said liquid in a molar ratio from 1/15 to 15/1.

Abstract: An aqueous alkaline processing liquid suitable for use in the silver complex diffusion transfer (DTR-) process, wherein said liquid contains one or more alkanolamines, the said alkanolamine(s) consisting of one or more tertiary alkanolamines in an amount in the range from 0.15 mol to 1.5 mol/l, and one or more secondary alkanolamines in an amount higher than 5 mol % but not higher than 100 mol % with respect to the amount of tertiary alkanolamine(s), and said liquid also contains a mixture of a silver image toning agent A being 1-phenyl-1H-tetrazole-5-thiol or a tautomer thereof and at least one other silver image toning agent B being a 1-phenyl-1H-tetrazole-5-thiol or a tautomer thereof, wherein the phenyl nucleus is substituted with halogen, the toning agent A and toning agent(s) B being present in said liquid in a molar ratio from 1/15 to 15/1.

Abstract: Disclosed is a silver complex diffusion transfer process which comprises processing a photosensitve material comprising a support and at least a silver halide emulsion layer provided thereon and an image receiving material comprising a support and at least an image receiving layer provided thereon which are brought into close contact with each other in a developing processing solution. This process is characterized in that said image receiving layer has 1-3 g/m.sup.2 of a hydrophilic colloid at least 80% by weight of which is gelatin; total amount of hydrophilic colloid present on the emulsion layer side of the photosensitive material is 5-8 g/m.sup.2 ; when the materials are immersed in a 0.1N aqueous sodium hydroxide solution at 20.degree. C. for 1 minute, amount of absorbed solution per 1 g of hydrophilic colloid is 3.

Abstract: Process for the production of a laminated article including a sheet support bearing a silver image produced by the silver complex diffusion transfer process in a layer containing developement nuclei, wherein such supported image is heat-laminated with a protective thermoplastic resin layer of sheet that covers it. The heat-lamination of the nuclei-containing layer with the silver image therein takes place in the presence of at least one of certain heterocyclic black-toning agents which are effective to prevent degradation of the neutral black coloration and density loss of the silver image as a result of heat-lamination.

Abstract: A non-light-sensitive image-receiving element useful in a silver complex diffusion transfer process includes at least one layer containing certain S-thiuronium alkyl sulfonates which act as tone controlling agents that accelerate the physical development of silver.

Abstract: A non-light-sensitive image-receiving element useful in a silver complex diffusion transfer process includes at least one layer containing certain tone controlling agents that accelerate the physical development of silver. Compounds useful for this purpose are alkyl disulfides substituted by a water solubilizing group, thiazolidine carboxylic acids, .gamma.-thiobutyrolactones, higher alkyl thioglycolates, and carboxy-substituted rhodanines.

Abstract: An epoxy resin comprising an active hydrogen compound having at least three active hydrogen atoms capable of reacting with an epoxy group in its molecule or butadine or isoprene as a main monomer is modified with an oligomer having on average at least 1.5 equivalents of active hydrogen capable of reacting with an epoxy group in its molecule. An epoxy resin modified with a bisphenol and a compound having active hydrogen or acid anhydride groups capable of reacting with an epoxy group is also provided. A toner containing the epoxy resin as a binder is useful in electrostatography.

Abstract: A method for processing an imagewise exposed photographic silver halide emulsion material using a receptor element for complexed silver halide which element contains a stabilizing agent corresponding to one of the following general formulae (I) or (II), tautomeric structures or a precursor form thereof: ##STR1## wherein: X represents hydrogen, alkali metal, ammonium or organic amine,Z represents the non-metallic atoms necessary to form a 5- or 6-membered heterocyclic nucleus, andeach of R.sup.1 and R.sup.2 (same or different) represents hydrogen, amino, alkyl, alkenyl, cycloalkyl, aryl, alkoxy, alkylthio, alkylsulfonyl, sulfamoyl, acyl, --SH or a heterocyclic group.