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Photochemistry and Photobiology

Curtis D Mobley, Brian L Diffey
Atmospheric and oceanic radiative transfer models were used to compute spectral radiances between 285 and 400 nm onto horizontal and vertical plane surfaces over water. The calculations kept track of the contributions by the sun's direct beam, by diffuse sky radiance, by radiance reflected from the sea surface, and by water-leaving radiance. Clear, hazy, and cloudy sky conditions were simulated for a range of sun zenith angles, wind speeds, and atmospheric ozone concentrations. The radiances were used to estimate erythemal exposures due to the sun and sky, as well as from radiation reflected by the sea surface and backscattered from the water column...
January 8, 2018: Photochemistry and Photobiology
Ivan V Shelaev, Mahir D Mamedov, Fedor E Gostev, Arseny V Aybush, Meng Li, Jonathan Nguyen, Barry D Bruce, Victor A Nadtochenko
Photosystem I (PSI) is a Type-I reaction center and the largest photosynthetic complex to be characterized. In cyanobacteria, PSI is organized as a trimer with a three-fold axis of symmetry. Recently, a tetrameric form of PSI has been identified in cyanobacteria. Plastids in plants and algae only contain monomeric PSI, suggesting that tetrameric PSI may be key in the transition from ancestral cyanobacterial trimeric PSI to plant/algal monomeric PSI. We have investigated the kinetics of e- transfer to the initial acceptor in PSI tetramer isolated from Chroococcidiopsis TS-821...
January 8, 2018: Photochemistry and Photobiology
Dalila E Orallo, M Florencia Fangio, Martin Poblet, Mario O Carignan, Luis Bernal, José I Carreto, Sonia G Bertolotti, M Sandra Churio
The photostability and photophysical properties of the dimethyl ester of the mycosporine-like amino acid shinorine have been experimentally evaluated in aqueous solution and in the presence of direct micelles prepared with a cationic or an anionic detergent, respectively. In comparison with shinorine, the ester molecule increases the photostability, the fluorescence quantum yield and the fluorescence lifetime in water as well as in the micellar solutions. The effects are more pronounced in sodium dodecyl sulfate solutions and suggest that the electrostatic attractions with the micellar interface contribute to limit the movement of the molecules and influence the relative rate of their deactivation channels...
January 6, 2018: Photochemistry and Photobiology
Jeffrey D Laskin, Yi-Hua Jan, Michele M Jetter, Christophe D Guillon, Thomas M Mariano, Diane E Heck, Ned D Heindel
Photosensitizers are used in the treatment of epidermal proliferation and differentiation disorders such as psoriasis and vitiligo. In the present studies, a ring-expanded carbon homologue of the linear psoralen (furo[3,2-g]benzopyran-7-one) class of photosensitizers, 4,10-dimethyl-2H,8H-benzo[1,2-b:5,4-b']dipyran-2-one (NDH2476), was synthesized and analyzed for biological activity. Following activation by ultraviolet light (UVA, 320-400 nm), NDH2476 was found to be a potent inhibitor of keratinocyte growth (IC50 = 9 nM)...
January 6, 2018: Photochemistry and Photobiology
Malte C Grüner, Silke Niemann, Andreas Faust, Cristian A Strassert
Herein we present a comparative study about the photoinactivation of Staphylococcus aureus (Gram-positive model) and Escherichia coli (Gram-negative model) employing a neutral and a dicationic axially functionalized SiIV phthalocyanine. Depending on the charge of the siloxane moiety (neutral monosaccharide or cationic ammonium salt), different interactions with the bacteria were observed and a differential photoinactivation was facilitated. The intensity of the fluorescence labelling correlated with the photoinactivation of the two types of bacteria: while the neutral species only significantly affected the Gram-positive cells, we observed that the positively charged photosensitizer interacted both with the Gram-positive and with the Gram-negative models...
December 29, 2017: Photochemistry and Photobiology
Viviane Jettar, Marcelo Napimoga, Fabiana Freitas, Juliana Clemente-Napimoga, Selly Suzuki, Victor Montalli, Aguinaldo Garcez
Orthodontic tooth movement is based on mechanical forces inducing bone remodeling and several methods have been proposed to increase tooth movement, including photobiomodulation. This study evaluated, in an animal model, the effects of photobiomodulation on SOFAT - a secreted osteoclastogenic factor of activated T cells and RANK-L during tooth movement. The results showed that tooth displacement, RANK-L and SOFAT levels were significantly greater compared to control group. SOFAT may play an important role in bone remodeling during orthodontic movement, possibly increasing the osteoclast cells at the compression area and bone remodeling activity...
December 23, 2017: Photochemistry and Photobiology
Edith Dube, David O Oluwole, Tebello Nyokong
This work reports on the synthesis of tetrakis-[(thiophineethoxy) phthalocyaninato] indium(II) chloride (3). The photophysical behaviour of complex 3 was compared to that of the Zn derivative (tetrakis-[(thiophineethoxy) phthalocyaninato] zinc(II) (complex 2)). The compounds were interacted with gold-speckled silica (GSS) nanoparticles via Au-S self assembly to afford the conjugates (2-GSS and 3-GSS). The photophysicochemical behaviour of the compounds and their conjugates were assessed. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet and singlet oxygen quantum yields in comparison to complexes 2 and 3 alone...
December 22, 2017: Photochemistry and Photobiology
Taisa Nogueira Pansani, Fernanda Gonçalves Basso, Diana Gabriela Soares, Ana Paula da Silveira Turrioni, Josimeri Hebling, Carlos Alberto de Souza Costa
This study assessed the effects of photobiomodulation (PBM) to cells previously exposed to lipopolysaccharides (LPS). Human gingival fibroblasts (HGF) and epithelial cells (HaCaT) were seeded in wells of 24-well plates containing complete culture medium (DMEM). After 24h, the DMEM was replaced by serum-free DMEM, and cells were exposed to LPS of Escherichia coli (E. coli) (10 μg/mL) for 24, 48, and 72h. The cells were subjected to specific parameters of phototherapy (PT) (LASERTable-InGaAsP-780 ± 3nm, 25mW, 3J/cm2 )...
December 18, 2017: Photochemistry and Photobiology
Satoshi Yoshimoto, Moemi Yoshida, Hideya Ando, Masamitsu Ichihashi
To understand a role of UVA radiation in photo-aging of the skin, we established a model of photo-aging cells using cultured human dermal fibroblasts. Repeated low dose UVA radiation for 10 consecutive days induced senescence in fibroblasts, characterized with 1) increased level of senescence-associated β-galactosidase, 2) flattened large cell shape, 3) accumulation of reactive oxygen species, 4) yellowish coloration and 5) expression of p16. These were also observed in chronologically aged fibroblasts (doubling times >20), whereas none of these were detected in young cells (doubling times <10)...
December 18, 2017: Photochemistry and Photobiology
Chaohui Huang, Hui Chen, Lei Zhao, Xuan He, Weixin Li, Wei Fang, Guanghui Wang
The hierarchical porous heterostructured MIL-125/TiO2 @SiO2 composites are successfully obtained by biogenic-templated method using rice husk both as biomorphic. The products are characterized by X-ray diffraction, N2 -adsorption-desorption analysis, scanning electron microscopy and Fourier transform infrared spectroscopy. The results reveal that MIL-125/TiO2 @SiO2 possesses a hierarchical porous structure in scale from micrometer to nanometer with high Brunauer-Emmett-Teller (BET) surface area (385.7 - 902...
December 18, 2017: Photochemistry and Photobiology
Schindra Kumar Ray, Dipesh Dhakal, Soo Wohn Lee
The microwave hydrothermal process was used for the synthesis of various morphologies of α-NiMoO4 by simply adjusting the pH during experimental conditions. The effect of morphology/size on the photocatalytic performances for degradation of malachite green (MG) has been investigated under UV-Vis/visible light irradiation. Nanorod morphology has strong tendency to degrade (88.18%) the MG as compared to spherical quantum-sized (57.65%) and layered square microsheet (37.98%) under UV-Vis irradiation in 180 min...
December 18, 2017: Photochemistry and Photobiology
Mohan Yu, Yoshihiro Ohmiya, Panče Naumov, Ya-Jun Liu
Latia neritoides is a small limpet-like snail that produces a bright green bioluminescence (BL) via a unique light-emitting system. The process, mechanism and even light emitter of its light emission remain unknown, although this BL has been known for decades. Unlike the other BL systems, neither the luciferin (Luc) nor the oxyluciferin (OxyLuc) of Latia is fluorescent according to the previous experiments. In order to help to identify its bioluminophore, we studied the geometrical and electronic structures and absorption and fluorescence spectra of Latia Luc and its six analogues as well as its OxyLuc in the gas phase and in water...
December 18, 2017: Photochemistry and Photobiology
Guoyan Dong, Xin Wang, Zhiwu Chen, Zhenya Lu
TiO2 (Degussa P25) photocatalysts harboring an abundant oxygen vacancies (vacuum P25) were manufactured using a simple and economic vacuum deoxidation process. Control experiments showed that temperature and time of vacuum deoxidation had a significant effect on vacuum P25 photocatalytic activity. After 240 min of visible light illumination, the optimal vacuum P25 photocatalysts (vacuum deoxidation treated at 330°C for 3h) reaches as high as 94% and 88% of photodegradation efficiency for Rhodamine B (RhB) and tetracycline respectively, which are around 4...
December 18, 2017: Photochemistry and Photobiology
Xiaofei Zhao, Limin Song, Shujuan Zhang
Novel AgCl/Ag3 PO4 photocatalysts were synthesized by a simple precipitation method, in which AgCl was coated onto Ag3 PO4 particles, as uncovered by X-ray diffractometry, transmission electron microscopy, and ultraviolet-visible spectrometry. Different from previous research on photocatalytic degradation, we studied the performance of methyl orange photodegradation on a small continuous flow reactor. The highest degradation activity of 97% was achieved by the 2 wt.% AgCl/Ag3 PO4 after 8 min of visible light irradiation, while pure Ag3 PO4 degraded only 71% methyl orange under same conditions...
December 18, 2017: Photochemistry and Photobiology
Bernd Herzog, Amélie Schultheiss, Jochen Giesinger
The sun protection factor (SPF) is the most important quantity to characterize the performance of sunscreens. As the standard method for its determination is based on clinical trials involving irradiation of human volunteers, calculations of sunscreen performance have become quite popular in order to reduce the number of in vivo studies. Such simulations imply the calculation of UV-transmittance of the sunscreen film using the amounts and spectroscopic properties of the UV-absorbers employed, and presuppose the validity of the Beer-Lambert law...
November 23, 2017: Photochemistry and Photobiology
Masahiko Taniguchi, Hai Du, Jonathan S Lindsey
The PhotochemCAD program, developed over 30 years, is described comprehensively with focus on features of the most recent version (PhotochemCAD 3). The program is equipped with a streamlined user interface and provisions for handling multiple spectral databases. Eight modules enable calculations to be performed on the basis of the spectra in the databases. The calculational modules provide results concerning properties of individual compounds (oscillator strength, transition dipole moment, natural radiative lifetime), interactions of multiple compounds (Förster energy transfer, Dexter energy transfer, analysis of energy transfer among an array of chromophores), and composition of mixtures (multicomponent analysis)...
November 22, 2017: Photochemistry and Photobiology
Caroline C da Silva, Sérgio P Chaves Júnior, Gabriela L D Pereira, Karla B F C da Fontes, Lívia A A Antunes, Helvécio C C Póvoa, Leonardo S Antunes, Natalia L P Póvoa Iorio
This study evaluated antimicrobial photodynamic therapy (aPDT) as an adjunct to endodontic treatment. Ten uniradicular teeth (control group (CG)= 4 (2 and test group (TG)= 6) with primary endodontic infections, from both genders, between 17 and 65 years old, were analyzed. Microbiological samples were collected before and after chemical-mechanical instrumentation (CMI), after aPDT (for the TG), and after the removal of the temporary restorations (second session). In TG, the aPDT was performed with 100 μg/mL methylene blue and irradiated with low power laser (InGaAIP, 660 nm; 100 mW; 40 sec) with a fiber-coupled optical laser...
November 22, 2017: Photochemistry and Photobiology
Masahiko Taniguchi, Jonathan S Lindsey
The design of new molecules for photochemical studies typically requires knowledge of spectral features of pertinent chromophores beginning with the absorption spectrum (λabs ) and accompanying molar absorption coefficient (ε, M(-1) cm(-1) ) and often extending to the fluorescence spectrum (λem ) and fluorescence quantum yield (Φf ), where the fluorescence properties may be of direct relevance or useful as proxies to gain insight into the nature of the first excited singlet state. PhotochemCAD databases, developed over a period of 30 years, are described here...
November 22, 2017: Photochemistry and Photobiology
Magdalena Ciążyńska, Igor A Bednarski, Karolina Wódz, Joanna Narbutt, Michał Sobjanek, Anna Woźniacka, Aleksandra Lesiak
Ultraviolet radiation (UVR) is one of the most important environmental factors involved in photoaging. Exposure to UVR leads to dysregulation of expression of cell-cycle-related proteins which play key role in skin photodegradation that pretends to develop carcinogenesis. This study examines the role of various UVB doses on the expression of transforming growth factor beta (TGF-β), Smad2, cathepsin K, progerin and matrix metalloproteinases (MMPs)-1,-3,-8,-9. A group consisting of 63 healthy individuals underwent one of the following treatments: 1) whole-body exposed to UVB irradiation on each of 10 consecutive days with 0...
November 22, 2017: Photochemistry and Photobiology
Michael R Hamblin
Photobiomodulation (PBM) involves the use of red or near-infrared light at low power densities to produce a beneficial effect on cells or tissues. PBM therapy is used to reduce pain, inflammation, edema, and to regenerate damaged tissues such as wounds, bones and tendons. The primary site of light absorption in mammalian cells has been identified as the mitochondria, and more specifically, cytochrome c oxidase (CCO). It is hypothesized that inhibitory nitric oxide can be dissociated from CCO thus restoring electron transport and increasing mitochondrial membrane potential...
November 22, 2017: Photochemistry and Photobiology
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