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Photochemical & Photobiological Sciences

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https://www.readbyqxmd.com/read/28102421/the-nature-of-the-light-absorption-and-emission-transitions-of-4-hydroxybenzophenone-in-different-solvents-a-combined-computational-and-experimental-study
#1
Francesco Barsotti, Giovanni Ghigo, Silvia Berto, Davide Vione
The photophysics and photochemistry of 4-hydroxybenzophenone (4HOBP) are interesting because they can give some insight into the behavior of humic material. Here we show that 4HOBP has a number of fluorescence peaks: (i) an intense one at excitation/emission wavelengths Ex/Em ∼ 200-230/280-370 nm, likely due to an excitation transition from S0 to S5 or S6, followed by S2 → S0 in emission (Sn denotes the singlet states of 4HOBP); (ii) a minor peak at Ex/Em ∼ 270-300/320-360 nm (S0 → S2 in absorption and S2 → S0 in emission), and (iii) very interesting signals in the typical emission region of humic substances, most notably at Ex/Em ∼ 200-220/400-500 nm and Ex/Em ∼ 260-280/400-470 nm (in both cases the emission corresponded to an S1 → S0 transition)...
January 19, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28102417/does-sunlight-protect-us-from-cancer
#2
Jacqueline E Marshall, Scott N Byrne
The Ultraviolet (UV) radiation contained in sunlight is a powerful mutagen and immune suppressant which partly explains why exposure to solar UV is the biggest risk factor for the development of cutaneous tumours. Evidence is building that sunlight may be protective against some internal malignancies. Because patients with these tumours are often vitamin D deficient, this has led some to propose that vitamin D supplementation will be beneficial in the treatment of these cancers. However, the results from already completed trials have been disappointing which has given weight to the argument that there must be something else about sunlight that explains its cancer-protecting properties...
January 19, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28092390/asthma-comparing-the-impact-of-vitamin-d-versus-uvr-on-clinical-and-immune-parameters
#3
Kylie A Morgan, Elizabeth H Mann, Antony R Young, Catherine M Hawrylowicz
The incidence of asthma has increased markedly since the 1960s and is currently estimated to affect more than 300 million individuals worldwide. A number of environmental factors are implicated in asthma pathogenesis, one of which is vitamin D. Vitamin D deficiency is a global health concern and has increased in parallel with asthma incidence. Epidemiological studies report associations between low vitamin D status, assessed as circulating levels of 25-hydroxyvitamin D, with asthma incidence, severity, exacerbations and responses to treatment...
January 16, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28091662/self-assembly-optical-thermal-and-electrochemical-properties-of-bis-n-benzyl-perylene-diimide-dye
#4
Devrim Ozdal, Nur P Aydinlik, Jagadeesh B Bodapati, Huriye Icil
Flexible methylene containing N,N'-bis-(benzyl)-3,4,9,10-perylenebis(dicarboximide) (1) was synthesized. Self-assembled microstructures (hollow tubes, average length and width: 7.7 and 0.8 μm) of 1 were also prepared (T-1). Comparative studies of the optical, thermal and electrochemical properties of 1 and T-1 have been extensively carried out. The T-1 hallow tubes have shown extremely broad absorption in the near-infrared (300-800 nm) region (NIR) even in solution and intensified conductivity in the solid-state compared to 1...
January 16, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28078341/the-role-of-uv-radiation-and-vitamin-d-in-the-seasonality-and-outcomes-of-infectious-disease
#5
Abhimanyu, Anna K Coussens
The seasonality of infectious disease outbreaks suggests that environmental conditions have a significant effect on disease risk. One of the major environmental factors that can affect this is solar radiation, primarily acting through ultraviolet radiation (UVR), and its subsequent control of vitamin D production. Here we show how UVR and vitamin D, which are modified by latitude and season, can affect host and pathogen fitness and relate them to the outcomes of bacterial, viral and vector-borne infections...
January 12, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28074966/the-relationship-between-sun-exposure-and-all-cause-mortality
#6
Pelle G Lindqvist, Mona Landin-Olsson
We aimed to conduct a narrative review of the rapid advances in knowledge regarding sun exposure and all-cause mortality. Data support the hypothesis that sun exposure avoidance is a major risk factor for all-cause mortality in adjusted analysis (age, income, education, marital status, smoking, and comorbidity). This was caused by an increased risk of death due to cardiovascular disease (CVD) and noncancer/non-CVD. However, the increased life span among those with high sun exposure naturally results in an increased prevalence of cancer death...
January 11, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28070587/highly-selective-colorimetric-detection-of-cyanide-anions-in-aqueous-media-by-triphenylamine-and-phenanthro-9-10-d-imidazole-based-probes
#7
Arockiam Jesin Beneto, Ayyanar Siva
Two novel fluorescent probes based on triphenylamine (TPC) and phenanthro(9,10-d-imidazole) (PITP) have been synthesized and studied as cyanide selective indicators in aqueous media. Complete colour bleaching was observed due to the nucleophilic addition of cyanide to the 2-vinylmalononitrile of TPC, which results in the disruption of the extended conjugation and turns off the intramolecular charge transfer (ICT) process. Furthermore, a visible color change was observed with a large Stokes shift (108 nm) upon the addition of cyanide anions to PITP, due to the formation of hydrogen bonding between the CN(-) anion and -NH of PITP, which increased the electron density on the donor moiety and induced strong ICT...
January 10, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28070585/effect-of-proline-on-biochemical-and-molecular-mechanisms-in-lettuce-lactuca-sativa-l-exposed-to-uv-b-radiation
#8
Ozkan Aksakal, Dilruba Tabay, Aslıhan Esringu, Feyza Icoglu Aksakal, Nevzat Esim
The purpose of the present study was to evaluate the role of proline (Pro) in relieving UV-B radiation-induced oxidative stress in lettuce. Lettuce seedlings were exposed to 3.3 W m(-2) UV-B radiation for 12 h after pre-treatment sprayed with 20 mM Pro. The data for malondialdehyde (MDA), hydrogen peroxide (H2O2), endogenous Pro level, the activities of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD)], total phenolic concentration, antioxidant capacity, expression of phenylalanine ammonia lyase (PAL), γ-tocopherol methyltransferase (γ-TMT) and proline dehydrogenase (ProDH) genes, phytohormone levels such as abscisic acid (ABA), gibberellic acid (GA), indole acetic acid (IAA) and salicylic acid (SA), soluble sugars and organic acids were recorded...
January 10, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28054069/challenge-and-perspective-the-relevance-of-ultraviolet-uv-radiation-and-the-vitamin-d-endocrine-system-vdes-for-psoriasis-and-other-inflammatory-skin-diseases
#9
Jörg Reichrath, Roman Saternus, Thomas Vogt
During evolution, the ability of many organisms to synthesize vitamin D photochemically represented, and still represents, a major driving factor for the development of life on earth. In humans because not more than 10-20% of the requirement of vitamin D can be satisfied by the diet (under most living conditions in the US and Europe), the remaining 80-90% need to be photochemically synthesized in the skin through the action of solar or artificial ultraviolet-B (UV-B) radiation. The skin is a key organ of the human body's vitamin D endocrine system (VDES), representing both the site of vitamin D synthesis and a target tissue for biologically active vitamin D metabolites...
January 5, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28054064/photophysical-properties-of-rhenium-i-complexes-and-photosensitized-generation-of-singlet-oxygen
#10
Luiz Duarte Ramos, Hugo Moreira da Cruz, Karina P Morelli Frin
fac-[Re(ampy)(CO)3(NN)](+) complexes (ampy = 2-aminomethylpyridine and NN = 1,10-phenanthroline (phen), and 2,2'-bipyridine (bpy)) were synthesized, purified and characterized by proton nuclear magnetic resonance ((1)H NMR), UV-visible and Fourier-transformed infrared (FT-IR) spectroscopies, and their photophysical properties were investigated using steady state and time-resolved emission spectroscopies. The electronic absorption spectra exhibit two main absorption bands: the higher energy band, which was assigned to intraligand transition (IL), and the lower energy band assigned to metal-to-ligand charge transfer (MLCT)...
January 5, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28009891/ultraviolet-radiation-vitamin-d-and-the-development-of-obesity-metabolic-syndrome-and-type-2-diabetes
#11
Shelley Gorman, Robyn M Lucas, Aidan Allen-Hall, Naomi Fleury, Martin Feelisch
Obesity is increasing in prevalence in many countries around the world. Its causes have been traditionally ascribed to a model where energy intake exceeds energy consumption. Reduced energy output in the form of exercise is associated with less sun exposure as many of these activities occur outdoors. This review explores the potential for ultraviolet radiation (UVR), derived from sun exposure, to affect the development of obesity and two of its metabolic co-morbidities, type-2 diabetes and metabolic syndrome...
December 23, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28009890/the-health-benefits-of-uv-radiation-exposure-through-vitamin-d-production-or-non-vitamin-d-pathways-blood-pressure-and-cardiovascular-disease
#12
Richard B Weller
The detrimental effects of ultraviolet radiation are well known. Skin cancer, photo-aging, and induction or exacerbation of photosensitive dermatoses have been the focus of most photobiological research since 1928 when Findlay confirmed the carcinogenicity of ultraviolet radiation using a murine model of skin cancer. The epidemiological, mechanistic and clinical trial data have enabled the classification by the International Agency for Research on Cancer of ultraviolet radiation as a Group 1 ('sufficient evidence') carcinogen for human skin...
December 23, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28009887/responses-of-crepis-japonica-induced-by-supplemental-blue-light-and-uv-a-radiation
#13
L F da S Constantino, L B Dos S Nascimento, L M Casanova, N Dos S Moreira, E A Menezes, R L Esteves, S S Costa, E S Tavares
Crepis japonica (L.) D.C. (Asteraceae), a weed with antioxidant, antiallergenic, antiviral and antitumor properties displays both medicinal properties and nutritional value. This study aims to assess the effects of a supplementation of blue light and UV-A radiation on the growth, leaf anatomical structure and phenolic profile of the aerial parts of Crepis japonica. Plants were grown under two light treatments: W (control - white light), W + B (white light supplemented with blue light) and W + UV-A (white light supplemented with UV-A radiation)...
December 23, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28009884/synthesis-and-fluorescence-properties-of-dioxa-dithia-and-diselena-3-3-1-3-pyrenophanes
#14
Hajime Maeda, Masato Hironishi, Rikiya Ishibashi, Kazuhiko Mizuno, Masahito Segi
[3.3](1,3)Pyrenophanes tethered by oxygen (1), sulfur (2) and selenium (3) atoms were synthesized and the structural and physical properties of these substances were determined. The absorption maxima of the [3.3](1,3)pyrenophanes were observed to shift to longer wavelengths in the order of 1 < 2 < 3. The fluorescence spectra of 1-3 contained both monomer and intramolecular excimer emissions, which correspond to anti and syn conformers, respectively. The ratios of the intensities of intramolecular excimer to monomer emission were observed to increase with the increasing solvent polarity...
December 23, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28009886/primary-photophysical-and-photochemical-processes-for-hexachloroosmate-iv-in-aqueous-solution
#15
Evgeni M Glebov, Ivan P Pozdnyakov, Svetlana G Matveeva, Alexei A Melnikov, Sergey V Chekalin, Marina V Rogozina, Vladislav V Yudanov, Vjacheslav P Grivin, Victor F Plyusnin
The photoaquation of the Os(IV)Cl6(2-) complex was studied by means of stationary photolysis, nanosecond laser flash photolysis and ultrafast kinetic spectroscopy. The Os(IV)Cl5(OH)(2-) complex was found to be the only reaction product. The quantum yield of photoaquation is rather low and wavelength-dependent. No impact of redox processes on photoaquation was revealed. The total characteristic lifetime of the process is about 80 ps. Three intermediates were recorded in the femto- and picosecond time domains and assigned to different Os(iv) species...
December 22, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/27982146/pulsed-nd-yag-laser-induced-photoreaction-of-cis-cis-1-3-cyclooctadiene-at-266-nm-selective-cyclization-to-cis-bicyclo-4-2-0-oct-7-ene
#16
Keiko Komori-Orisaku, Yui Hirose, Izumi Iwakura
Nanosecond-scale pulsed laser irradiation of cis,cis-1,3-cyclooctadiene via an Nd:YAG laser at 266 nm induced highly selective cyclization of the 1,3-diene moiety to afford cis-bicyclo[4.2.0]oct-7-ene in high yield. The pulsed Nd:YAG laser light is highly monochromatic thereby allowing efficient control of the photoreaction selectivity by controlling the photostationary state.
December 16, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/27982141/hydrogen-bond-dynamics-governs-the-effective-photoprotection-mechanism-of-plant-phenolic-sunscreens
#17
Fang Liu, Likai Du, Zhenggang Lan, Jun Gao
Sinapic acid derivatives are important sunscreen species in natural plants, which could provide protection from solar UV radiation. Using a combination of ultrafast excited state dynamics, together with classical molecular dynamics studies, we demonstrate that there is direct coupling of hydrogen bond motion with excited state photoprotection dynamics as part of the basic mechanism in solution. Beyond the intra-molecular degree of freedom, the inter-molecular motions on all timescales are potentially important for the photochemical or photophysical events, ranging from the ultrafast hydrogen bond motion to solvent rearrangements...
December 16, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/27976780/a-method-for-the-quantification-of-8-methoxypsoralen-by-mass-spectrometry-for-offline-extracorporeal-photopheresis
#18
Viola Hähnel, Frauke Dormann, Athanasios Nitsopoulos, Albrecht Friedle, Norbert Ahrens
BACKGROUND: Extracorporeal photopheresis (ECP) is an efficient method to treat various autoimmune diseases, cutaneous T-cell lymphoma, and graft-versus-host disease. It is based on the ex vivo inactivation of lymphocytes by 8-methoxypsoralen (8-MOP)/UV light treatment. Despite the adhesive, lipophilic nature of 8-MOP, no quality control is established for the ECP procedure. METHODS: We developed a sensitive high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) assay to monitor residual 8-MOP concentration after UVA irradiation in the whole blood supernatant after acetonitrile precipitation...
December 15, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/27976779/parietin-an-efficient-photo-screening-pigment-in-vivo-with-good-photosensitizing-and-photodynamic-antibacterial-effects-in-vitro
#19
Laura R Comini, F Eduardo Morán Vieyra, Ricardo A Mignone, Paulina L Páez, M Laura Mugas, Brenda S Konigheim, José L Cabrera, Susana C Núñez Montoya, Claudio D Borsarelli
The photophysical, photoinduced pro-oxidant and antibacterial properties in vitro of the natural occurring parietin (PTN; 1,8-dihydroxy-3-methoxy-6-methyl-9,10-anthraquinone) were evaluated. PTN was extracted from the lichen identified as Teloschistes flavicans (Sw.) Norm. (Telochistaceae). Results indicate that in chloroform solution, PTN presents spectroscopic features corresponding to an excited-state intramolecular proton-transfer (ESIPT) state with partial keto-enol tautomerization. In argon-saturated solutions, the singlet excited state is poorly fluorescent (ΦF = 0...
December 15, 2016: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/27976777/arginine-induced-porphyrin-based-self-assembled-nanostructures-for-photocatalytic-applications-under-simulated-sunlight-irradiation
#20
Duong Duc La, Sidhanath V Bhosale, Lathe A Jones, Sheshanath V Bhosale
In this communication, we have investigated the arginine-induced fabrication of porphyrin (TCPP)-based supramolecular nanostructures. These self-assembled porphyrin nanostructures such as nanobelts show enhanced photocatalytic activity for the photodegradation of pollutant Rhodamine B under simulated visible-light irradiation.
December 15, 2016: Photochemical & Photobiological Sciences
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