A world progress report of science and technology of photography is given. News and topics are complied by referring to journals and periodicals published in foreign countries as well in Japan in the year 1986. Items are industrial activities, silver halide photographic materials, color photography, non-silver systems, photographic theory, photographic processing, applications of photography, cameras, instant photography, electrophotography and equipments.

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A detailed review is made for the mechanism of gold+sulfur sensitization. Silver-gold sulfide AgAuS isformed more rapidly than silver sulfide by decomposition of labilesulfur compound in gold +sulfur sensitization. Silver-gold sulfide speck promotes theformation of silver sulfide especially at (100) surface in providing decomposition site, and then size distribution of the silver sulfide specks becomes moreuniform than that bysulfur sensitization. There are not so many experimental results supporting that gold atom speck acts as sensitizing center. Two main photographic actions are present atgold+sulfur sensitization, one is electron trapping and the other is gold latensification. Not gold atom speck nor gold-silver sulfide speck but silver sulfide speck acts as electron trap. Characterisity of silver sulfide speck depends on their size, and as the onesformed ingold+sulfur sensitization have more uniform size distribution, almost all specks have a good characterisity for electron trapping. Since latent image specksformed ingold+sulfur sensitized emulsion contain gold atom, minimum size for developability becomes small. There are some other actions for sensitization but they are not so important.Gold+sulfur sensitization has many ways for sensitizing action and the high sensitivity is owing to its complexity.

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To observe the behaviour of hydroquinone (H₂Q) in the development process, AgBr formed electrochemically on a rotating ring disk electrode (RRDE) was taken as a model of a photographic emulsion. In a developing solution at pH 8.6, the development rate was greatly affected by the content of O₂ in solution and ambient light. In the dark, the development rate decreased with increasing the O₂ content, while in room light an opposite result was obtained. These results are attributed to the influence of quinone (Q), an oxidized product of H₂Q.

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In order to elucidate fading mechanisms of azomethine dyes for image formation in color photography, remarkable photo-fading reactions of model dyes with benzophenone (BP) in degassed ethanol are investigated by flash photolysis. In these solutions, the BP lowest triplet state abstracts a α-hydrogen of a ethanol molecule and produces a BP kethyl radical (KR). Then the KR initiates the fading reaction by addition of a hydrogen to an azomethine group of a dye molecule. The second order decay constant of KR is found to be (1.3±0.2) ×10⁸M^-1s^-1 and the second order fading constant of the cyan dye to be (5.2±0.8) ×10⁸M^-1s^-1. Effects on the fading reaction by KR scavengers such as dietyl maleate and methyl viologen (MV) are investigated. It is concluded that the fading reaction is not initiated only by KR but also by other radicals such as CH₃CHOH, and that the latter process makes probably a large contribution to the fading reaction. Moreover MV and AgNO₃ show interesting effects on the dye fading and the KR decay.

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Charge acceptance memory effect was studied in the photoreceptor consist of organic photoconductor [(Poly-N-vinylcarbazole (PVK), Polyvinylcarbazole ethylacryrate (Poly-CEA))], memory materials such as Crystal Violet, Carbazole dye and polyester binder.
The optimum of dye concentration was about 0.1 mol%/photoconductor in monomer unit for the memory formation. And the sensitization of the memory effect by corona pre-charging was remarkable and the increase of its sensitivity was more than two orders ratio compared with only exposure.
By comparing the difference of memory behaviors between PVK and Poly-CEA, the doped dye seemed to become the memory center by light absorption.
It was found from the above experimental results that the large size of the counter anion of dye such as BF₄^- and C10₄^- gave remarkable effect to increase the memory sensitivity.

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The memory mechanisms of conductivity and charge acceptance change for a photoreceptor consisting of ionic dye or colored spiropyran and Poly-N-vinyl carbazole (PVK) were studied by measurement of corona charge acceptance, current-voltage characteristics with a sandwich cell and ESR measurement. And it is concluded that the memory is formed by two different cases.
1) When the memory layer is based on ohmic contacting substrate (Au), the photogenerated dye radicals in the bulk seemed to be responsible for memory formation by changing the conductivity. In other words, it is cosidered that the change of dye condition from ionic to non-ionic by exposure caused the elimination of hole trapping site and increased the bulk conductivity.
2) When non-ohmic contacting substrates (ITO, Al) are used, it was also considered that the radicals at the interface could act the key role to assist hole injection from the electrode into memory layer.

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Microstructures in developed silver filaments have been examined by high resolution electron microscooy.
It was confirmed that thin filaments (ca. 20 nm in diameter) are nearly defect-free, whereas thicker filaments (>20 nm) have a number of crystal defects such as stacking faults, twin boundaries, and small angle tilt grain boundaries containing edge dislocations.

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