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Photochemical & Photobiological Sciences

Feyza Icoglu Aksakal, Abdulkadir Ciltas
Ultraviolet B (UV-B) radiation is an environmental stressor with detrimental effects on many aquatic organisms including fish. In addition, UV-B exposure combined with other environmental factors could have even more negative effects. The purpose of this study was to investigate the effect of UV-B radiation exposure on zebrafish embryos/larvae in terms of survival, developmental toxicity and the mRNA levels of the genes related to oxidative stress and innate immune response at different temperatures (24 °C, 28 °C and 30 °C)...
November 17, 2017: Photochemical & Photobiological Sciences
M Danko, P Hrdlovič, A Martinická, A Benda, M Cigáň
A series of ionic benzotristhiazolium (BTT) push-pull chromophores, with different nitrogen donor groups and different lengths of conjugated bridges, was successfully doped in polar polymer matrices (PVC and PSS). The spectral (photophysical) properties of their low concentration thin polymeric films are compared with those in solution and are discussed in terms of matrix polarity/viscosity influence, specific polymer-chromophore interaction, structure-spectral property relationship and Twisted Intramolecular Charge-Transfer (TICT) state formation...
November 16, 2017: Photochemical & Photobiological Sciences
Marina V Rogozina, Vladislav V Yudanov, Roman G Fedunov, Ivan P Pozdnyakov, Alexey A Melnikov, Sergey V Chekalin, Evgeni M Glebov
Two mechanisms of Os(IV)Cl6(2-) photolysis were studied by means of quantum chemical calculations in gas and aqueous phases. The difference between these mechanisms is in the nature of the possible Os(iv) key intermediates (KI). According to calculations, the intermediate is an Os(IV)Cl5(-) complex of square pyramidal coordination geometry. The calculations do not give an opportunity to make an unambiguous choice between the triplet and quintet multiplicities of Os(IV)Cl5(-). The calculated CASSCF/IMCP-SR1 transition energies for (5)Os(IV)Cl5(-) are lower than for (3)Os(IV)Cl5(-), while the calculated XMC-QDPT2/SBKJC spectra for the triplet state are in better agreement with the experimental absorption spectrum of the KI than for the quintet state...
November 16, 2017: Photochemical & Photobiological Sciences
E Despagnet-Ayoub, W W Kramer, W Sattler, A Sattler, P J LaBeaume, J W Thackeray, J F Cameron, T Cardolaccia, A A Rachford, J R Winkler, H B Gray
The products from the 193 nm irradiation of triphenylsulfonium nonaflate (TPS) embedded in a poly(methyl methacrylate) (PMMA) film have been characterized. The analysis of the photoproduct formation was performed using chromatographic techniques including HPLC, GPC and GC-MS as well as UV-vis and NMR spectroscopic methods. Two previously unreported TPS photoproducts, triphenylene and dibenzothiophene, were detected; additionally, GPC and DOSY-NMR spectroscopic analyses after irradiation suggested that TPS fragments had been incorporated into the polymer film...
November 16, 2017: Photochemical & Photobiological Sciences
Prue H Hart, Mary Norval
The realisation that UV radiation (UVR) exposure could induce a suppressed immune environment for the initiation of carcinogenesis in the skin was first described more than 40 years ago. Van der Leun and his colleagues contributed to this area in the 1980s and 90s by experiments in mice involving UV wavelength and dose-dependency in the formation of such tumours, in addition to illustrating both the local and systemic effect of the UVR on the immune system. Since these early days, many aspects of the complex pathways of UV-induced immunosuppression have been studied and are outlined in this review...
November 14, 2017: Photochemical & Photobiological Sciences
C F Calver, B A Lago, K S Schanze, G Cosa
Single molecule fluorescence (SMF) studies on conjugated polymers yield enhanced information on exciton dynamics and on the interplay between polymer conformation/morphology and photophysical behavior. SMF studies, however, demand good signal stability, excellent photostability, and high photon yields (a measure of both photostability and brightness) and thus the development of strategies to help conjugated polymers (CPs) meet these requirements is a topic of great interest. Here, we evaluate the effect of a number of triplet quencher additives on the photostability of a 49-mer long poly(phenylene-ethynylene) conjugated polymer bearing carboxylate side groups (PPE-CO2-49) that is deposited onto 100 nm diameter SiO2 nanoparticles (NPs)...
November 14, 2017: Photochemical & Photobiological Sciences
Ju Byeong Chae, Hyo Jung Jang, Cheal Kim
A novel colorimetric chemosensor 1 was designed and synthesized for Fe(3+/2+) and pyrophosphate. Sensor 1 showed a selective color change toward both Fe(3+) and Fe(2+) from yellow to brown in a near-perfect aqueous solution. The detection limits (0.36 μM and 0.37 μM) for Fe(3+) and Fe(2+) were much lower than the guideline (5.37 μM) set by the Environmental Protection Agency (EPA) for iron in drinking water. Sensor 1 could be used to quantify Fe(3+) in real water samples. Moreover, the resulting Fe(3+)-2·1 complex can detect pyrophosphate selectively over various anions especially including phosphate-based anions through a metal-complex displacement method...
November 9, 2017: Photochemical & Photobiological Sciences
Mikhail V Rusalov, Valery V Volchkov, Vladimir L Ivanov, Mikhail Ya Melnikov, Ivan V Shelaev, Fedor E Gostev, Victor A Nadtochenko, Artem I Vedernikov, Sergey P Gromov, Michael V Alfimov
The dynamics of the excited states of a supramolecular complex with a charge transfer between (E)-bis(18-crown-6)stilbene and 4,4'-(E)-ethene-1,2-diylbis[1-(2-ammonioethyl)pyridinium]tetraperchlorate was studied by means of femtosecond transient spectroscopy. It is found that the characteristic time of the conversion of the locally excited (LE) state into the charge transfer (CT) state is equal to 300 fs, whereas the characteristic time of the conversion of the CT state into the ground state is equal to 400 fs...
November 8, 2017: Photochemical & Photobiological Sciences
Minki Baek, Eun-Ju Kim, Seok Won Hong, Wooyul Kim, Kijung Yong
Due to its high light absorption coefficient and appropriate bandgap, CuInS2 (CIS) has been receiving much attention as an absorber material for thin film solar cells and also as a visible light photocatalyst. Herein we present heterostructured CIS/ZnO nanorods (NRs) in an attempt to enhance light absorption and facilitate charge separation/transfer in the photocatalysis system. CIS nanoparticles (NPs) were directly deposited on ZnO nanorod arrays (NRAs) to fabricate heterostructured CIS/ZnO NRAs using an environmentally benign, non-hydrazine solution reaction...
November 8, 2017: Photochemical & Photobiological Sciences
Xiang Li, Yongmei He, Chunmei Xie, Yanqun Zu, Fangdong Zhan, Xinyue Mei, Yang Xia, Yuan Li
The traditional rice variety "Baijiaolaojing" was planted in Yuanyang terraces (1600 m altitude) under field conditions. The effects of enhanced UV-B radiation (0 kJ m(-2), 2.5 kJ m(-2), 5.0 kJ m(-2) and 7.5 kJ m(-2)) on the rice-Magnaporthe oryzae system were studied with respect to the Magnaporthe oryzae infection, the disease-resistance physiology of the rice and the rice blast disease condition. The results showed that under enhanced UV-B radiation, the infectivity of Magnaporthe oryzae was decreased, which could significantly inhibit its growth and sporulation...
November 7, 2017: Photochemical & Photobiological Sciences
Michael Glueck, Barbara Schamberger, Peter Eckl, Kristjan Plaetzer
Outbreaks of foodborne diseases are regularly reported worldwide. In particular, uncooked plant food is considered risky in terms of microbiological safety. Food is also the most important transmission route for resistant microorganisms from animals to humans. Photodynamic Decontamination (PDc) of foodstuff was recently introduced as a novel approach for increasing microbiological food safety. We investigated the efficiency of PDc on plant food with different geometries (flat, spherical and complex) using a two-dimensional LED array as a light source (435 nm, 33...
November 6, 2017: Photochemical & Photobiological Sciences
Emiko Wada, Akanksha Tyagi, Akira Yamamoto, Hisao Yoshida
A new catalytic route for the lactonization of diols was developed by using a metal-loaded TiO2 photocatalyst. In particular, Pt-loaded rutile TiO2 exhibited a high photocatalytic activity with high selectivity. In addition, it was found that a heterogeneous acid catalyst can accelerate this photocatalytic lactonization.
November 3, 2017: Photochemical & Photobiological Sciences
A Akbari
The one-pot photocatalytic synthesis of benzo[f]chromene was performed at room temperature by the addition of benzyl alcohol, malononitrile and β-naphthol in contact with an illuminated nano-SnO2/TiO2 composite. This study illustrated the potential of photochemical synthesis of benzo[f]chromene. A simple procedure was proposed for the synthesis of a nano-SnO2/TiO2 composite using the sol-gel method by hydrolysis of tin(iv) chloride and titanium(iv) chloride at room temperature in the presence of polyethylene glycol 200, diethanolamine, and distilled water...
November 1, 2017: Photochemical & Photobiological Sciences
K Kinastowska, J Barroso, L Yate, V Pavlov, A Chuvilin, W Bartkowiak, M Grzelczak
In photobiocatalytical processes involving the simultaneous oxidation of water and reduction of specific organic molecules (e.g., cofactors), the lack of physical separation of the redox half-reactions adversely affects the product stability. This is largely because organic molecules are generally less stable within harsh oxidative environments. In general, surface co-catalysts are able to improve the selectivity of photocatalysts towards water oxidation. However, harsh oxidative environments reduce the chemical stability of the organic molecules...
October 31, 2017: Photochemical & Photobiological Sciences
P Sarbadhikary, A Dube
The insertion of suitable metals or high Z elements in tumour-avid tetrapyrrole compounds is a promising approach to obtain potential agents for multimodal cancer therapeutics and tumour imaging. Using chlorin p6, a chlorophyll derivative, we synthesized a novel iodinated chlorin p6-copper complex (ICp6-Cu) that can be applied to the photodynamic therapy and photon activation therapy of cancer. In the present study, we investigated the interaction of ICp6-Cu with human serum albumin (HSA) using UV-Vis absorption and fluorescence spectroscopy...
October 31, 2017: Photochemical & Photobiological Sciences
Brian L Diffey, Peter M Farr
The earliest contribution made by Jan van der Leun to the field of photobiology was studying the mechanism of UV-induced erythema in human skin - a subject he chose for his PhD in the 1960s. His contribution to this topic encouraged us to continue this work and over a number of years in the 1980s and 1990s, we carried out several studies on quantitative aspects of UV erythema. A major part of Jan's thesis focused on diffusion processes in UV erythema and his observations led him to conclude that erythema induced by radiation with wavelengths of around 300 nm was due to the actions of a diffusing mediator arising in the epidermis, whereas radiation at shorter wavelengths around 254 nm, caused erythema by exerting a direct effect on the dermal blood vessels...
October 26, 2017: Photochemical & Photobiological Sciences
Kacey C Hall, Andrew T Franks, Rory C McAtee, Michael S Wang, Vivian I Lu, Katherine J Franz
The range of applications for photoswitching moieties is diverse, and the ability to design switches with variable photochemical and physical properties is consequently important for realizing their potential. Previously we reported on the photochromism of (E)-N'-(1-(2-hydroxyphenyl)ethylidene)isonicotinohydrazide (HAPI), an aroylhydrazone compound first developed as a transition metal chelator. Herein we report the synthesis of structurally related aroylhydrazone chelators and explore the effect of these modifications on their UVA, UVC and blue light photoreactivity, photostationary state composition, photoisomer thermal stability, and relative iron(iii) binding affinity...
November 8, 2017: Photochemical & Photobiological Sciences
Ruben Mercadé-Prieto, Luis Rodriguez-Rivera, Xiao Dong Chen
Rhodamine B (RhB) is a well known dye extensively used in thermometric studies, either considering the decrease in the fluorescence intensity or the lifetime (τ) with temperature. Lifetime measurements are preferred over intensity ones as they are more robust. In order to expand microscopy thermometry to complex food fluids, the effect of solutes on the τ of RhB was studied using fluorescence lifetime imaging microscopy (FLIM) in a two-photon microscope. Polysaccharides of different molecular weights (glucose, lactose, dextran, maltodextrin, and sodium alginate), as well as whey proteins, were considered as typical model food ingredients...
November 8, 2017: Photochemical & Photobiological Sciences
R Daniel Cacciari, Eugenia Reynoso, Hernán A Montejano, M Alicia Biasutti
The use of biologically active substances with anti-inflammatory properties such as corticosteroids has increased considerably in the last few decades. Particularly, the compound we are interested in, prednisolone (Predn), is a glucocorticoid with high biological activity. This compound absorbs UV radiation and may participate in photochemical processes, which can result in its own decomposition. These processes could result in the formation of free radicals or reactive oxygen species (ROS). On these grounds, the kinetic and mechanistic aspects of the direct photodegradation of Predn have been studied in aqueous medium under different atmospheric conditions by stationary and time-resolved techniques...
November 8, 2017: Photochemical & Photobiological Sciences
Sara Moghnie, Artak Tovmasyan, James Craik, Ines Batinic-Haberle, Ludmil Benov
Photodynamic therapy (PDT) is a promising alternative approach particularly attractive for treatment of localized fungal infections. It is based on compounds, photosensitizers (PSs), which when excited with visible light, generate reactive species that ultimately cause cell death. Such species have short lifespans; as a consequence, efficiency and selectivity of the PDT treatment depend mainly on the properties of the PSs. This study is the first to explore the effect of cationic porphyrin-based photosensitizers on Saccharomyces cerevisiae, a member of the fungus kingdom...
November 8, 2017: Photochemical & Photobiological Sciences
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