Abstract: An actinic ray-sensitive or radiation-sensitive resin composition in the present invention contains a nitrogen-containing compound (N) which is represented by the following general formula (N1): wherein, in the general formula (N1), X represents a group including a hetero atom; L represents a single bond or an alkylene group; R2 represents a substituent, in the case where a plurality of R2's are present, they may be the same as or different from each other and a plurality of R2's may be bonded to each other to form a ring; R3 represents a hydrogen atom or a substituent; and n represents an integer of 0 to 4.

Abstract: The subject matter of the invention is a method for producing illuminated, holographic media comprising a photopolymer formulation having the adjustable mechanical modulus GUV. A further subject matter of the invention is an illuminated, holographic medium that can be obtained by means of the method according to the invention.

Abstract: A photosensitive resin composition for a color filter includes (A) a dye polymer composite including a repeating unit derived from a compound represented by the following Chemical Formula 1, wherein in Chemical Formula 1, each substituent is the same as described in the detailed description, (B) an acrylic-based photopolymerizable monomer, (C) a photopolymerization initiator, and (D) a solvent, and a color filter using the same.

Abstract: In the method for forming a protective coat on an electrode for a touch panel according to the invention, a photosensitive layer comprising a photosensitive resin composition containing a binder polymer having a carboxyl group and an acid value of 30 to 120 mgKOH/g, a photopolymerizable compound having at least three ethylenic unsaturated groups, and a photopolymerization initiator, is formed on a base material having an electrode for a touch panel, prescribed sections of the photosensitive layer are cured by irradiation with active light rays and then the sections other than the prescribed sections are removed, to form a protective coat comprising the cured sections of the photosensitive resin composition covering all or a portion of the electrode.

Abstract: The present disclosure provides a micro-composite material used in the fabrication of three-dimensional objects, and associated methods and systems. In one example, a micro-composite material used in the fabrication of a three-dimensional object can comprise micronized polymeric particles; a photocurable curing agent; and a dye present in the micro-composite material in an amount at from 0.0001 wt % to 0.1 wt %, the dye having a ?max between 350 nm and 800 nm.

Abstract: The present invention provides a CTP photosensitive flexographic printing original plate which causes no printing blur while the conventional printing durability, developing property and image-reproducing property are still maintained. A photosensitive resin composition for CTP flexographic printing original plate containing at least a hydrophobic polymer obtained from water-dispersible latex (A), a hydrophilic polymer (B), a photopolymerizable unsaturated compound (C), a photopolymerization initiator (D), and if necessary, rubber (E), characterized in that, the photopolymerizable unsaturated compound (C) comprises a photopolymerizable oligomer containing no hydroxyl group (C-1), a hydroxyl group-containing photopolymerizable monomer having a pentaerythritol skeleton, a dipentaerythritol skeleton or a glycerol skeleton (C-2) and, optionally, a photopolymerizable monomer containing no hydroxyl group (C-3).

Abstract: Compounds of formula (I), (II), and (III), wherein R1, R2, R?2 and R??2 for example are C1-C20alkyl, provided that at least one of R1, R2, R?2 and R??2 carries a specified substituent; R3, R4, and R5 for example independently of one another are hydrogen or a defined substituent provided that at least one of R3, R4 or R5 is other than hydrogen or C1-C20alkyl; R6, R7, R8, R?7, RV, R?8, R?6, R?7, R??6 and R??7 for example independently of one another have one of the meanings as given for R3, R4, and R5; and R9 for example is C1-C20alkyl; exhibit an unexpectedly good performance in photopolymerization reactions.

Abstract: There is provided a pattern forming method comprising (A) forming a film by using an actinic ray-sensitive or radiation-sensitive resin composition containing a resin containing a repeating unit having a phenol skeleton and a repeating unit having a group capable of decomposing by the action of an acid to produce an alcoholic hydroxy group; (B) exposing the film; and (C) developing the exposed film by using an organic solvent-containing developer.

Abstract: A negative tone resist composition for solvent developing including: a base component (A) which exhibits decreased solubility in an organic solvent under the action of acid; a photodecomposable quencher (D0) which generates acid having a pKa of 2.0 or more; and a fluorine additive (F) containing a fluorine-containing polymeric compound (f) which has a structural unit (f0-1) represented by general formula (f0-1) shown below or a structural unit (f0-2) represented by general formula (f0-2) shown below. In the formulae, R represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; and Rf1 represents an aliphatic hydrocarbon group containing a fluorine atom.

Abstract: A negative photosensitive resin composition including a novolac resin (A), a photoacid generator (B), a basic compound (C), a cross-linking agent (D), and a solvent (E) is provided. The novolac resin (A) includes a hydroxy-type novolac resin (A-1) and a xylenol-type novolac resin (A-2). The hydroxy-type novolac resin (A-1) is synthesized by polycondensing a hydroxybenzaldehyde compound and an aromatic hydroxy compound. The xylenol-type novolac resin (A-2) is synthesized by polycondensing an aldehyde compound and a xylenol compound.

Abstract: Disclosed are compositions for negative-working thick film photophotoresists based on acrylic co-polymers. Also included are methods of using the compositions.

Abstract: Monomeric formulations appropriate for creating self-propagating polymer optical waveguides, and methods for their fabrication, are disclosed. Multiple polymer waveguides can be fabricated simultaneously into a three-dimensional micro-truss structure, while avoiding significant polymerization outside the confines of the illuminated region. The formulations described to accomplish this controlled polymerization include species containing one or more unsaturated carbon-carbon bonds capable of being free-radical polymerized in the presence of photoinitiator and either a radical inhibitor species or a solvent, or both. The radical inhibitor and/or solvent are included to minimize heat buildup and thermal decomposition of initiator. This invention enhances the versatility of the chemistry by significantly increasing the number of chemical building blocks available for micro-truss fabrication.

Abstract: A method of patterning a device comprises providing on a device substrate a layer of a fluorinated photopolymer comprising at least three distinct repeating units including a first repeating unit having a fluorine-containing group, a second repeating unit having an acid- or alcohol-forming precursor group, and a third repeating unit having a sensitizing dye. The photopolymer has a total fluorine content in a range of 15 to 60% by weight. The photopolymer layer is exposed to patterned light and contacted with a developing agent to remove a portion of exposed photopolymer layer in accordance with the patterned light, thereby forming a developed structure having a first pattern of photopolymer covering the substrate and a complementary second pattern of uncovered substrate corresponding to the removed portion of photopolymer. The developing agent comprises at least 50% by volume of a fluorinated solvent.

Abstract: There is provided an actinic ray-sensitive or radiation-sensitive resin composition, having: (A) a resin having a repeating unit represented by formula (I); (B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation; and (C) a resin having at least one repeating unit (x) out of a repeating unit represented by formula (II) and a repeating unit represented by formula (III) and containing substantially neither fluorine atom nor silicon atom, wherein the content of the repeating unit (x) is 90% or more by mole based on all repeating units in the resin (C).

Abstract: A resist composition comprising a compound (m0) (wherein Rb1 represents an electron withdrawing group; Rb2 and Rb3 each independently represents an aryl group, an alkyl group or an alkenyl group, provided that Rb2 and Rb3 may be mutually bonded to form a ring with the sulfur atom; and X0? represents a monovalent counteranion).

Abstract: A colored radiation-sensitive composition contains (A) a dye multimer, (B) a pigment, (C) a polymerizable compound, (D) a photopolymerization initiator, and (E) a dispersion resin obtained by reacting a polymer, which has a hydroxyl group on one terminal, with an acid anhydride.

Abstract: There is provided a pattern forming method, including: (a) forming a film by an actinic ray-sensitive or radiation-sensitive resin composition containing: (A) a resin capable of increasing polarity by an action of an acid to decrease solubility in an organic solvent-containing developer, (B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation, (C) a solvent, and (D) a resin, which contains substantially no fluorine atom and silicon atom and is other than the resin (A), (b) exposing the film; and (c) performing development using the organic solvent-containing developer to form a negative type pattern, wherein a receding contact angle of water on the film formed by (a) is 70° or more.

Abstract: There is provided an actinic ray-sensitive or radiation-sensitive resin composition containing a compound capable of generating an acid upon irradiation with an actinic ray or radiation, represented by the formula (Z1), and the formula (Z1) is defined as herein, and a resist film formed using the actinic ray-sensitive or radiation-sensitive resin composition, a pattern forming method comprising a step of forming a film by using the actinic ray-sensitive or radiation-sensitive resin composition, a step of exposing the film, and a step of developing the exposed film, a method for manufacturing an electronic device, comprising the pattern forming method, and an electronic device manufactured by the method for manufacturing an electronic device.

Abstract: The radiation-sensitive resin composition includes a compound represented by a following formula (1), and a resin. The resin has an acid-dissociable group, is insoluble or hardly soluble in an alkali, and turns to be soluble in an alkali when the acid-dissociable group is dissociated. R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R1 represents a hydrocarbon group having 1 to 20 carbon atoms or the like, R2 to R5 each independently represent an alkyl group having 1 to 4 carbon atoms, an alicyclic hydrocarbon group having 4 to 20 carbon atoms, or the like, and R6 represents a halogen atom or the like.

Abstract: Lithographic printing plates and processes for preparing the lithographic printing plates are provided. The plates have excellent printing durability, staining resistance and staining resistance over time. The lithographic printing plate precursor includes: a substrate; a photosensitive layer provided on the substrate; and an extra layer optionally provided between the substrate and the photosensitive layer. The photosensitive layer or the extra layer adjacent to the substrate contains (A) a copolymer. The copolymer (A) includes: (a1) a repeating unit of formula (a1-1) below in a side chain, and (a2) a repeating unit having at least one of the structures represented by formulae (a2-1) to (a2-6) shown in the specification in a side chain. L1, Z1, R1, and R21, R22 and R23 in formula (a1-1) and the variables in formulae (a2-1) to (a2-6) are as defined in the specification.

Abstract: The invention provides a patterning process for forming a negative pattern by lithography, comprising at least the steps of: using a composition for forming silicon-containing film, containing specific silicon-containing compound (A) and an organic solvent (B), to form a silicon-containing film; using a silicon-free resist composition to form a photoresist film on the silicon-containing film; heat-treating the photoresist film, and subsequently exposing the photoresist film to a high energy beam; and using a developer comprising an organic solvent to dissolve an unexposed area of the photoresist film, thereby obtaining a negative pattern. There can be a patterning process, which is optimum as a patterning process of a negative resist to be formed by adopting organic solvent-based development, and a composition for forming silicon-containing film to be used in the process.

Abstract: The present invention provides a radiation-sensitive resin composition that contains a polymer having a structural unit that includes an acid-labile group; and an acid generator, wherein the acid generator includes a compound including a sulfonate anion having SO3?, wherein a hydrogen atom or an electron-donating group bonds to an ? carbon atom with respect to SO3?, and an electron-withdrawing group bonds to a ? carbon atom with respect to SO3?; and a radiation-degradable onium cation. The compound preferably has a group represented by the following formula (1-1) or (1-2). In the following formulae (1-1) and (1-2), R1 and R2 each independently represent a hydrogen atom or a monovalent electron-donating group. R3 represent a monovalent electron-withdrawing group. R4 represents a hydrogen atom or a monovalent hydrocarbon group.

Abstract: [Object] To provide a photosensitive siloxane resin composition excellent in alkali-solubility and in sensitivity, and also to provide a pattern-formation method employing that. [Means] The present invention provides a photosensitive siloxane resin composition comprising: a siloxane resin having silanol groups or alkoxysilyl groups, a crown ether, a photosensitive material, and an organic solvent. This photosensitive composition is cast on a substrate, subjected to imagewise exposure, treated with an alkali aqueous solution, and cured to form a pattern.

Abstract: The present application relates to a photoactive compound including an oxime ester group and a phosphonate group together, and a photosensitive resin composition comprising the same, the compound of the present application having excellent storage stability and high-temperature process characteristics.

Abstract: A photocurable composition comprising a photoresist component, and an ethylenically unsaturated perfluoropolyether is disclosed. The composition enables easier release of phototool from a photoresist.

Abstract: The present invention provides a colored curable composition including a phthalocyanine pigment, a dioxazine pigment, a dye, a polymerization initiator, a polymerizable compound and a solvent; and a colored curable composition including a phthalocyanine pigment, a dye multimer having a polymerizable group and a group derived from a dipyrromethene dye, a polymerization initiator, a polymerizable compound and a solvent.

Abstract: With the objective of providing a photosensitive transparent resin composition that is reduced in the exposure illuminance dependency, allows high residual film ratio and little development scum and can stably form a pattern with good resolution, a color filter ensuring little decrease in the transmittance for visible light and enabling display of a high-quality definite image, and a production method thereof, there is provided a photosensitive transparent resin composition containing at least a polymerizable monomer, an alkali-soluble resin, a photopolymerization initiator and a compound represented by the following formula (I): wherein each of R1 and R2 independently represents a hydrogen atom, an alkyl group having a carbon number of 1 to 20 or an aryl group having a carbon number of 6 to 20, R1 and R2 may be the same or different but are not a hydrogen atom at the same time, R1 and R2 may form a cyclic amino group together with the nitrogen atom, each of R3 and R4 independently represents an electron-

Abstract: The invention relates to an imaging element and a method of using the imaging element to form a recording element. The imaging element includes a composition sensitive to actinic radiation at a first wavelength and a photoluminescent tag that is responsive to radiation at a second wavelength different from the first wavelength. The photoluminescent tag can be used to authenticate the identity of the element, provide information about the element, and/or to establish one or more conditions in a device used to prepare the recording element from the imaging element.

Abstract: A cyclic compound of the present invention has a molecular weight of 500 to 5000, and is represented by the following formula (1):

Abstract: A photosensitive resin composition is disclosed. The disclosed photosensitive resin composition includes an acryl-based copolymer formed by copolymerizing i) unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, or a mixture thereof, and ii) an olefin-based unsaturated compound or a mixture thereof, a dissolution inhibitor in which a phenolic hydroxyl group is protected by an acid-degradable acetal or ketal group, a photoacid generator, and a solvent.

Abstract: The invention relates to a photopolymer formulation comprising matrix polymers, writing monomers and photo initiators, to a method for producing said photopolymer formulation, a photopolymer formulation obtained according to said method, a sheeting, a film, a layer, a layer structure or a moulded body made from said photopolymer formulation and to the use of said photopolymer formulation for producing optical elements, in particular for producing holographic elements and images.

Abstract: There is provided a photosensitive resin composition containing (A) an alkali-soluble resin, (B) a compound which generates an acid when exposed to light, (C) a thermal crosslinking agent, and (D) a nitrogen-containing aromatic compound represented by the following formula (1): wherein R1 represents a hydrogen atom or a hydrocarbon group; R2 represents a hydrogen atom, an amino group or a phenyl group; and A and B each independently represent a nitrogen atom, or a carbon atom and a hydrogen atom bonded thereto.

Abstract: A negative pattern is formed by coating a resist composition comprising a polymer comprising recurring units of formulae (1) and (2) and a photoacid generator of formula (3) onto a substrate, baking, exposure, PEB and developing in an organic solvent. In formulae (1) and (2), R1 is H, F, CH3 or CF3, Z is a single bond, phenylene, naphthylene, or (backbone)-C(?O)—O—Z?—, Z? is alkylene, phenylene or naphthylene, XA is an acid labile group, YL is H or a polar group. In formula (3), R2 and R3 are a monovalent hydrocarbon group, R4 is a divalent hydrocarbon group, or R2 and R3, or R2 and R4 may form a ring with the sulfur, L is a single bond or a divalent hydrocarbon group, Xa and Xb are H, F or CF3, and k is an integer of 1 to 4.

Abstract: A photosensitive polysiloxane composition including a nitrogen-containing heterocyclic compound (A), a polysiloxane (B), an o-naphthoquinone diazide sulfonate (C), and a solvent (D) is provided.

Abstract: A resist composition including a base component which exhibits changed solubility in a developing solution under action of acid and an acid generator which generates acid upon exposure, the base component containing a polymeric compound containing a structural unit represented by general formula (a0-1) and the acid generator containing a compound represented by general formula (b1). In the formulae, R represents H, an alkyl group of C1 to 5 or a halogenated alkyl group of C1 to 5; Ya1 represents a single bond or a divalent linking group; La1 and La2 represents —SO2— or —C(?O)—; Ra1 represents a cyclic group which may have a substituent and the like; n1 and n2 represents 0 or 1; R11 represents a cyclic group of C5 to 30 which may have a substituent; V11 represents a single bond or an alkylene group of C1 to 6; L11 represents an ester bond; Y11 represents an alkylene group of C1 to 5 which may have a fluorine atom; m represents an integer of 1 or more; and Mm+ represents an organic cation having a valency of m.

Abstract: The present invention relates to a photoactive compound having a novel structure and a photosensitive resin composition including the same, and the photoactive compound according to the present invention has excellent sensitivity due to efficient absorption to a UV light source by including a nitro group and a phosphonate structure, and has excellent retention rate, mechanical strength, heat resistance, chemical resistance and developing resistance by improving solubility of the photosensitive resin composition by excellent compatibility of the phosphonate structure and a binder resin. Therefore, the photosensitive resin composition according to the present invention is useful to cure a column spacer, an overcoat, a passivation material and the like of a liquid crystal display device, and is useful in view of a high temperature process property.

Abstract: The present invention provides photoacid generators for use in chemically amplified resists and lithographic processes using the same.

Abstract: A negative pattern is formed by coating a resist composition comprising a polymer comprising recurring units of acid labile group-substituted vinyl alcohol and maleic anhydride and/or maleimide, an acid generator, and an organic solvent onto a substrate, prebaking, exposing to high-energy radiation, and developing in an organic solvent developer such that the unexposed region of resist film is dissolved away and the exposed region of resist film is not dissolved. In image formation via positive/negative reversal by organic solvent development, the resist film is characterized by a high dissolution contrast between the unexposed and exposed regions.

Abstract: A negative pattern is formed by applying a resist composition onto a substrate, prebaking, exposing to high-energy radiation, PEB, and developing the exposed resist film in an organic solvent developer to dissolve the unexposed region of resist film. The resist composition is based on a polymer comprising recurring units (a1) of formula (1) wherein R1 is H or CH3, R2 and R3 are H, F or a monovalent hydrocarbon group, R4 is H or a monovalent hydrocarbon group, R5 and R6 are a monovalent hydrocarbon group, X1 is a divalent hydrocarbon group, and k1=0 or 1. A fine hole or trench pattern can be formed therefrom.

Abstract: A cyclic compound having a molecular weight of 500 to 5000 is represented by the following formula (1), wherein at least one of R0 is a monovalent group containing an iodine atom. Also disclosed are a method for producing the cyclic compound, a composition containing the cyclic compound, and a method for forming a resist pattern using the composition.

Abstract: There is provided a pattern forming method comprising (i) a step of forming a film by using an actinic ray-sensitive or radiation-sensitive resin composition containing (A) a resin capable of increasing the polarity by the action of an acid to decrease the solubility for an organic solvent-containing developer, (B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation, (C) a solvent, and (D) a resin substantially free from a fluorine atom and a silicon atom and different from the resin (A), (ii) a step of exposing the film, and (iii) a step of performing development by using an organic solvent-containing developer to form a negative pattern.

Abstract: A polyimide precursor and a polyimide precursor resin composition, the polyimide precursor having repeating units represented by formula (1) and a photosensitive resin composition comprising the polyimide precursor and a photoacid generator or photobase generator: where R1 is a tetravalent organic group; R2 is a divalent organic group; R1s may be the same or different from each other and R2s may be the same or different from each other in the repeating units; R3 and R4 respectively represent a monovalent organic group having a structure represented by formula (2) and may be the same or different from each other; and R3s and R4s in the repeating units may be the same or different from each other, respectively. R5, R6, R7 and R8 are as described in the specification.

Abstract: A resist composition includes a polymer that includes an acid-labile group-containing structural unit, a photoacid generator, and a solvent. The solvent includes a compound that includes a ketonic carbonyl group and an alcoholic hydroxyl group. The alcoholic hydroxyl group is preferably a tertiary alcoholic hydroxyl group. The solvent preferably further includes an alkylene glycol monoalkyl ether carboxylate.

Abstract: The present invention relates to a polyurethane composition comprising A) a polyisocyanate component comprising an exclusively diol-based NCO-terminated polyurethane prepolymer, wherein the NCO groups are bonded in a primary manner, B) an isocyanate-reactive polymer, C) a compound having groups which react by polymerizing with an ethylenically unsaturated compound under the action of actinic radiation (radiation-curing groups) wherein the compound is free of NCO groups, D) a free-radical stabilizer, E) a photoinitiator, F) optionally a catalyst, G) optionally assistants and additives.

Abstract: This invention provides a volume hologram photosensitive composition, which can realize a hologram having an excellent brightness and, at the same time, having excellent heat resistance and mechanical strength, and a photosensitive medium for volume hologram recording using the volume hologram photosensitive composition. The volume hologram photosensitive composition comprises at least a photopolymerizable monomer, a photopolymerization initiator, a sensitizing dye for sensitizing the initiator, and a binder resin. The binder resin comprises a heat curing resin, and optionally a thermoplastic resin, and the thermoplastic resin is contained in an amount of 0 to 25% by weight based on the total solid content of the photosensitive composition.

Abstract: A resist pattern-forming method includes coating a radiation-sensitive resin composition on a substrate to provide a resist film. The resist film is exposed. The exposed resist film is developed using a developer solution including no less than 80% by mass of an organic solvent. The radiation-sensitive resin composition includes a polymer, a radiation-sensitive acid generator, and an acid diffusion controller which includes a compound having an amide group. The polymer has a weight average molecular weight in terms of the polystyrene equivalent of greater than 6,000 and includes a first structural unit that includes an acid-labile group. The polymer includes less than 5 mol % or 0 mol % of a second structural unit that includes a hydroxyl group.

Abstract: An actinic ray-sensitive or radiation-sensitive resin composition, which is excellent in sensitivity, resolution, a pattern profile and a depth of focus (DOF), and, an actinic ray-sensitive or radiation-sensitive film and a pattern forming method, each using the same, are provided. The actinic ray-sensitive or radiation-sensitive resin composition includes a nitrogen-containing compound and a resin (Ab) capable of varying a polarity or an alkali solubility thereof by the action of an acid.

Abstract: A resist composition includes a high-molecular weight compound having a constituent unit (a0) represented by a general formula (a0-1), an acid generator component (B) which generates an acid upon exposure, and a photodegradable base (D1) which is decomposed upon exposure to lose acid diffusion controlling properties, and a mixing ratio of the component (D1) to the component (B) is 0.5 or more in terms of a molar ratio represented by (D1)/(B). In the formula (a0-1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; Ya01 represents a single bond or a divalent linking group; X01 represents a sulfur atom or an oxygen atom; and Ra01 represents an optionally substituted cyclic group, an optionally substituted chain alkyl group, or an optionally substituted chain alkenyl group.

Abstract: A resist composition which generates an acid upon exposure and exhibits changed solubility in a developing solution by the action of the acid contains a high-molecular weight compound (A1) having a constituent unit (a0) represented by a general formula (a0-1) and a constituent unit (a1-1) including a monocyclic group-containing acid decomposable group whose polarity increases by the action of an acid. In the formula (a0-1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; Ya01 represents a single bond or a divalent linking group; X01 represents a sulfur atom or an oxygen atom; and Ra01 represents an optionally substituted cyclic group, chain alkyl group, or chain alkenyl group.

Abstract: A resist composition contains a high-molecular weight compound which has a partial structure represented by a general formula (a0-r-1) and has a constituent unit represented by a general formula (a0-1). In the formula (a0-r-1), Y1 represents a divalent linking group; each of R2 and R3 represents a group having 0 to 20 carbon atoms, which is not a fluorine atom, and either R2 or R3 may form a ring with Y1; m represents an integer of 1 or more; and Mm+ represents an m-valent organic cation. In the formula (a0-1), R represents a hydrogen atom, an alkyl group, or a halogenated alkyl group; Ya01 represents a single bond or a divalent linking group; X01 represents a sulfur atom or an oxygen atom; and Ra01 represents an optionally substituted cyclic group, chain alkyl group or chain alkenyl group.