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The seven lowest lying singlet and triplet (X and 2 @Z + states, the first 3Z +, 3,@ii' and 3'@A) electronic states of AgI were studied through extensive complete active space self-consistent field + averaged coupled pair functional calculations, with relativistic effective core potentials and optimized Gaussian basis sets for both atoms. The 2 ¹&Zigma;[sup +] an ³&Zigma;[sup+ ] states show relative minima very near the equilibrium geometry of the ground state, while the former also has another minimum around 8.1 a.u. and is attractive up to 20 a.u. The lowest ¹Π state was found to be totally repulsive. The [sup 3,1]Δ and ³Π states present very shallow minima, around 5.2 a.u. for the δ states and at 7.4 a.u. for the ³Π state. The calculated spectroscopic constants for the ground and excited states are compared with the available experimental data and results are discussed in light of the known spectroscopy of the other silver halides. Even though the ³Π state is mostly repulsive, it is almost degenerate with the 2 ¹&Zigma;[sup +] one near the equilibrium geometry of the ground state, and lies within 4500 cm[sup -1] from the latter in the 5-9 a.u. range, thus a strong 2 [sup 1]&Zigma;[sup +]-³π mixture through the spin-orbit interaction is predicted to occur that will lead to the fine-structure (0[sup +]) single B state (dominated by the 2 ¹&Zigma;[sup +] component), recently Rydberg-Klein-Rees fitted to explain the revised B←X transitions [Stueber et al., J. Chem. Phys. 109, 9831 (1998)]. These results unequivocally assign the A ← X transition as arising from ³&Zigma; ← X ¹&Zigma;[sup +]. In this way accurate spectroscopic data have been derived that lead to new assignments and predictions for electronic states unobserved so far. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are emerging materials for electro-and photo-chemical applications, where an understanding of the underlying charge-transfer (CT) process will facilitate designing new materials. However, the involvement of counterions in traditional electrochemical experiments complicates the probe on the role of various components during a CT event. A CT reaction between photoexcited MOF linker and a node-anchored ferrocene, within mesoporous framework NU-1000, was spectroscopically probed without the involvement of electrolyte based counterions. Dielectric dependent CT kinetics indicate that the process involves a high reorganization energy that is required to polarize the node bound hydroxyl/aqua ligands. The findings have clear implication on the design of MOF-based electrocatalysis and photoelectrochemical devices. [ABSTRACT FROM AUTHOR]

The paper describes hydrometallurgical treatment of photographic effluent. A combined effect of cathodic current density and Na 2 SO 3 dosage on the purity of cathodic silver and efficiency of silver electrowinning from spent photographic fixer was shown. It was found that efficient silver recovery is possible at a gradual decrease in the cathodic current density in the subsequent electrolysis stages from an initial value of 0.1 A/dm 2 . Decrease in the Ag + ions concentration with the electrolysis time was accompanied by increased contamination of silver deposits with Ag 2 S, if no extra SO 3 2 − additive was used. 0.05–0.1 M SO 3 2 − addition to the electrolyte allowed to maintain constant Ag 2 S percentage (1–2 wt%) in the cathodic deposit. [ABSTRACT FROM AUTHOR]

Comical associations between the science of photography and ideas about race were common on both sides of the Atlantic in the decades after the medium's invention. Some humorists observed that no bourgeois sitter would welcome the sight of his "negative" or blackened self; others illustrated the cosmetic character of race by depicting the effects of photographic chemicals on human skin. This essay takes these racial jokes seriously by reading them as historically specific social commentary. Beginning with an analysis of the first book of photographic humor, Cuthbert Bede's Photographic Pleasures (I 855), it shows how this genre both reinforced and challenged popular conceptions of whiteness, blackness, and the photographic medium. [ABSTRACT FROM AUTHOR]

Abstract: The 1908 Nobel Prize in Physics was awarded to Luxembourgeois Gabriel Lippmann (1848–1921), Professor of Mathematical and Experimental Physics at la Sorbonne, for his method of reproducing colors photographically based on the theory of wave interference. In the preceding several years, the eminent neurohistologist – and avid photographer – Santiago Ramón y Cajal (1852–1934) had been experimenting with Lippmann heliochromes, studying under the microscope the structure of the laminae of Zenker that produce mixed colors, and especially white. Those studies led to a series of technical papers by Cajal, the culmination being an article published 100 years ago in the Annual Report of the Board of Regents of the Smithsonian Institution in Washington, DC. A few years later, Cajal published Photography in Colors, his classic monograph on the physicochemical principles of the ‘art of Daguerre,’ bearing further testimony to his exuberant productivity, far-reaching interests, and scientific genius. The present article reflects on the workings of the mind of Cajal and his fundamental knowledge that was a precondition for his success in neurohistology. It highlights the links between the early photographic studies of Cajal and Lippmann, masters of the biological and physical sciences, respectively. Special emphasis is placed on Lippmann''s discovery of heliochromes and the microscopic analyses performed on them by Cajal, including elements from relevant contemporary studies and discoveries. [Copyright &y& Elsevier]

The article examines the negative effects of linalool vapors on silver-gelatine photographs and bookbinding leathers. The authors used two test modes to create linalool vapors including evaporation and spraying into the atmosphere. Based on the results, the small liquid drops of the chemical substance that were in contact more rapidly with silver gelatine photographs were showing quickly signs of deterioration. Furthermore, the authors concluded that the use of linalool in preservation was not advisable and its exposure could pose a risk to sensitive people.

Two new HPTLC methods for quantification of isopropyl-9H-thioxanthen-9-one (ITX) in milk, yoghurt and fat samples have been developed. Extraction of ITX from milk and yoghurt was performed with a mixture of cyclohexane and ethyl acetate by employment of accelerated solvent extraction (ASE). For soy bean oil and margarine, a simple partitioning of ITX into acetonitrile was used. ITX and 2,4-diethyl-9H-thioxanthen-9-one (DTX) used as internal standard have been separated on silica gel 60 HPTLC plates with a mixture of toluene and n-hexane (4:1, v/v) and on RP18 HPTLC plates with a mixture of acetonitrile and water (9:1, v/v). Development was performed anti-parallel from both plate sides leading to a throughput of 36 separations in 7 min. Fluorescence measurement at 254/>400 nm was used for quantification. Limits of detection (S/N of 3) have been established to be 64 pg for ITX and DTX on both types of HPTLC plates. In fatty matrix (spiked butter) LOD of ITX was determined to be 1 μg kg−1. In the working range monitored (20–200 μg kg−1) polynomial regression of ITX showed a relative standard deviation (sdv) of ±1.51 % ( r=0.99981). Starting with the limit of quantification the response was linear (sdv=±2.18 %, r=0.99893). Regarding repeatability ( n=9) a coefficient of variation (CV) of 1.1 % was obtained for ITX at 32 ng on silica gel plates and of 2.9 % on reversed-phase plates. Repeatabilities ( n=4) of ITX determination at 20, 50 and 100 μg kg−1 in milk, yoghurt, soybean oil and margarine showed CVs between ±1.0 and 6.4 %. The results prove that modern planar chromatography is a rapid and cost-efficient alternative method to quantify ITX in milk-based or fatty matrices. Only positive results are confirmed by online ESI/MS in the SIM mode (LOQ 128 pg) and by DART/MS involving a minimal employment of the MS device, which is a further advantage of HPTLC. Overall mean recovery rates of ITX at 20 or 50 and 100 μg kg−1 ( n=8) were 41 % for milk, 70 % for yoghurt, 6 % for margarine and 12 % for soy bean oil. However, with the internal standard correction recoveries were about 130 % for milk and yoghurt and 70 and 97 % for margarine and soy bean oil, respectively. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

From the beginnings of photography, gold was considered as a potential imaging substance and in 1842 Sir John Herschel succeeded in inventing an iron-based process called chrysotype for making contact-prints in gold. Despite their stability, the process failed to compete with Talbot's silver photography and never gained acceptance into the photographic repertoire owing to its expense and technical difficulty. Nonetheless, there were sporadic attempts to `re-invent' gold printing - with little success - until the close of the nineteenth century, by which time gold had been condemned as `useless' per se for photographic imaging, despite its extensive employment for toning silver images to improve their stability and colour. In the alternative process revival of the 1980s, however, the application of some modern chemistry enabled an economic chrysotype printing process that competes with platinotype in image quality, thus vindicating Herschel's original visionary idea. [ABSTRACT FROM AUTHOR]

The influence of a chemical modification (hardening) on the behavior of photographic gelatins at an interface has been investigated. It has been established, using the Langmuir monolayer method, that the properties of the surface layers of a modified gelatin change at the water-air interface and the depth of modification influences the surface activity of the gelatin. The surface properties of gelatin gels were investigated by the method of wetting depending on the hardener nature and the gelatin molecular-mass composition. It has been established that the hydrophilicity of gelatin gels increases with increase in the content of α-chains and the surface of gelatin gels is additionally hydrophilized as a result of their modification. [ABSTRACT FROM AUTHOR]

The occurrence and causes of occupational dermatoses at a film laboratory following modernization was studied. In 1983 the film laboratory moved to new premises built to reduce exposure to hazardous chemicals. The study was carried out during 1983-1986 with repeated interviews and dermatological examinations of all employees (78 subjects) and patch testing those with a history of or with current chemical exposure or dermatitis (65 subjects). Of 54 chemically exposed subjects, 34 (63%) had a history of occupational dermatoses, and 12 (22%) were contact allergic to film chemicals. Current, probable occupational dermatoses were observed in 13 subjects - thereof 8 with hand eczema. No new case of occupational skin disease occurred during the investigation period, except for 1 case of ulceration from an add splash. Petrolatum mixtures of the colour developing agents, Metol and hydroquinone were found most suitable for patch testing, since these chemicals are unstable and/or cause irritation in aqueous solutions. It is concluded that occurrence and severity of occupational dermatoses had been reduced by the technical measures taken to reduce chemical exposure. [ABSTRACT FROM AUTHOR]

This article focuses on a case study of a 51-year-old man who developed a scaly eczema on the dorsum of his fingers. It was found out that he worked as a technician for a motion colour film processing laboratory. It was observed that while working in the laboratory patient has to deal with various process solutions to establish the concentration of ingredients. On patch testing with photographic chemicals it was observed that a vesicular reaction was produced to a dilution. Since the patient has been using disposable polyvinyl chloride gloves when handling solutions of persulphate bleach accelerator (PBA1) and taking care with the cleanliness of his bench. the rash has cleared. It appears that he had allergic contact due to PBA1.

The article focuses on photographic allergens. 277 material safety data sheets were obtained from Eastman Kodak Company for all chemicals used in their black and white, color, X-ray and microfilm developing systems. 16 potential allergens were identified in these systems. Of these only the first 8 are in the current Chemotechnique photographic series. 8 other chemicals in the current series were not identified in these systems. An additional chemical, sodium dichromate, was recently replaced by potassium permaganate in Kodak developer system cleaner.

The article highlights cases of occupational allergy to Kathon 886. First patient was a 48-year-old male telecommunications engineer employed by a major national news paper on maintenance. He noticed irritation on the hands and forearms during his work tenure. There was eczema affection the palmar and dorsal aspects of fingers. The second patient, a 19-year-old film processor developed forearm eczema during his work tenure. Patch testing produced positive allergic reactions to Algezid II and Kathon 886.

This article focuses on a case study of a 38 year old man, who had developed contact allergy to the photographic chemical PBA-1. He worked as film developer for 16 years without any skin problems. While as a chemical mixer, he developed an eczema and flared up on the back of the hand and it quickly spread to his arms. Patch testing was performed with the ICDRG standard series and some photographic chemicals from his work. Finn-Chambers® were used for the standard test and Al-test® for the photographic chemicals with Scanpor® surgical tape.