Photochromic properties of composite films of thermally irreversible diarylethenes and fulgimides in polytetrafluoroethylene matrix

Photochromic polymeric thin films have been prepared by vacuum codeposition of polytetrafluoroethylene (PTFE) and thermally irreversible photochromic compounds: the cyclopentene derivative of diarylethene and fulgimide. Their photochromic properties were studied using the spectral-kinetic method as compared with polymethyl methacrylate (PMMA) films filled with the same photochromic compounds prepared using the spin coating method. The films prepared using codeposition in vacuum are characterized by photochromic properties acceptable for recording media for 3D optical memor

A new thin film photochromic material: Oxygen-containing yttrium hydride

In this work we report on photochromism in transparent thin film samples of oxygen-containing yttrium hydride. Exposure to visible and ultraviolet (UV) light at moderate intensity triggers a decrease in the optical transmission of visible and infrared (IR) light. The photo-darkening is colour-neutral. We show that the optical transmission of samples of 500 nm thickness can be reduced by up to 50% after one hour of illumination with light of moderate intensity. The reaction is reversible and samples that are left in the dark return to the initial transparent state. The relaxation time in the dark depends on the temperature of the sample and the duration of the light exposure. The photochromic reaction takes place under ambient conditions in the as-deposited state of the thin-film samples.Comment: Accepted for publication in Solar Energy Materials and Solar Cell

ПОЛУЧЕНИЕ И ИЗУЧЕНИЕ ФОТОХРОМНОГО ПОВЕДЕНИЯ ЗАМЕЩЕННЫХ 5-ВИНИЛ-6'-НИТРО-1,3,3-ТРИМЕТИЛ-СПИРО(ИНДОЛИНО-2,2'-[2H]-ХРОМЕНОВ)

Few 5-vinyl substituted 6’-nitro-1,3,3-trimethylspiro(indolino-2,2’-[2H]chromenes) (6’-nitro-spiropyrans) were synthesized by a one-step method from 5-formyl precursor – 5-formyl-6’-nitro-1,3,3-trimethylspiro(indolino-2,2’- [2H]chromene) (1). 5-Vinyl-6’-nitro-spiropyran (2) was prepared by the Wittig olefination of 1 with an ylide, which was generated by the action of potassium tert-butylate on methyltriphenylphosphonium bromide in THF. E-6’- Nitro-5-(1’’-nitroethene-2’’-yl)-6’-nitro-spiropyran (3) was obtained by heating 1, nitromethane, ethylenediammonium diacetate at 50°С in absolute methanol and inert atmosphere. Compounds 1’’-[6’-nitro-spiropyran-5- yl]-2’’,2’’-dicyanoethylene (4) and E-1’’-[6’-nitro-spiropyran-5-yl]-2’’-cyano-2’’-methoxycarbonylethylene (5) were prepared from initial 1 by reflux in ammonium acetate / glacial acetic acid / benzene mixture with malonodinitrile or methyl 2-cyanoacetate, respectively. The procedure for synthesizing derivatives 2’’,2’’-dimethyl-5’’-(6’-nitrospiropyran-5-yl)methylidene-1’’,3’’-dioxane-4’’,6’’-dion (6) and 5’’,5’’-dimethyl-2’’-(6’-nitro-spiropyran-5-yl)- methylidenecyclohexane-1’’,3’’-dion (7) includes the interaction of Meldrum's acid or dimedone, accordingly, with 5-formyl precursor 1 by heating in ethanol in the presence of piperidine and molecular sieves (to bind the released water). The structures of the prepared compounds and their purity have been confirmed by physico-chemical analysis. A spectral kinetic study of the photochromic properties of the substituted 5-vinyl spiropyrans was carried out in toluene and ethanol solutions. The 5-vinyl-6’-nitro-spiropyran derivatives 2–7 described in this work are of interest for further synthetic transformations.Ряд замещенных 5-винил-6’-нитро-1,3,3-триметилспиро(индолино-2,2’-[2H]-хроменов) был получен одностадийными методами синтеза из 5-формильного предшественника. Структуры полученных соединений подтверждены методами физико-химического анализа. Проведены спектрально-кинетические исследования фотохромного поведения новых 5-винилзамещенных продуктов в растворах толуола и этанола

Synthetic and natural organic photochromic systems for optic application

Own results of the study and application of a number of organic synthetic photochromic systems in the optical devices are presented. These results are compared with the data obtained for natural photochromic bacteriorhodopsines. It was shown that synthetic photochromic systems are characterized by more wide functional possibilities as compared with the natural systems based on bacteriorhodopsine for application in the optical devices. Advances in application of synthetic and natural photochromic systems for light modulation and recording optical information as well as nonlinear transformation of laser irradiation are discussed

Variations in adrenal hormones in law enforcement servicemen during a mission to local armed conflict

In a previous study, we reported changes in the adrenocorticotropic hormone (ACTH) and cortisol secretion in blood samples from law enforcement personnel during the mission to local armed conflict region. In the present study, we demonstrate those changes collectively with additional data on changes in the adrenaline and noradrenaline in the urine samples of the same individuals. The study was conducted on 48 male officers who were deployed to an army conflict teritory for a duration of 4 months.At the onset of the mission, there was a modestincreasein all hormones corresponding to the general adaptation syndrome theory. As the mission started, significant increases were observed in the mean levels of the hormonal parameters in both serum and urine at different time points as compared to those before the mission. At first week of deployment, a sharp increase in the secretory activity of medulla and cortical adrenal gland was found and at the termination of the mission a dysfunction of hypophysis-adrenal gland regulation system was identified. These findings might lead to disturbances in interhormonal relationships and causedecreased stress tolerance in the relevant individals.</p