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https://www.readbyqxmd.com/read/29124652/red-shift-in-the-spectrum-of-a-chlorophyll-species-is-essential-for-the-drought-induced-dissipation-of-excess-light-energy-in-a-poikilohydric-moss-bryum-argenteum
#1
Yutaka Shibata, Ahmed Mohamed, Koichiro Taniyama, Kentaro Kanatani, Makiko Kosugi, Hiroshi Fukumura
Some mosses are extremely tolerant of drought stress. Their high drought tolerance relies on their ability to effectively dissipate absorbed light energy to heat under dry conditions. The energy dissipation mechanism in a drought-tolerant moss, Bryum argenteum, has been investigated using low-temperature picosecond time-resolved fluorescence spectroscopy. The results are compared between moss thalli samples harvested in Antarctica and in Japan. Both samples show almost the same quenching properties, suggesting an identical drought tolerance mechanism for the same species with two completely different habitats...
November 9, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/29119280/cross-talk-between-high-light-stress-and-plant-defence-to-the-two-spotted-spider-mite-in-arabidopsis-thaliana
#2
A K Barczak-Brzyżek, M Kiełkiewicz, P Gawroński, K Kot, M Filipecki, B Karpińska
Little is known about how plants deal with arthropod herbivores under the fluctuating light intensity and spectra which occur in natural environments. Moreover, the role of simultaneous stress such as excess light (EL) in the regulation of plant responses to herbivores is poorly characterized. In the current study, we focused on a mite-herbivore, specifically, the two-spotted spider mite (TSSM), which is one of the major agricultural pests worldwide. Our results showed that TSSM-induced leaf damage (visualized by trypan blue staining) and oviposition rate (measured as daily female fecundity) decreased after EL pre-treatment in wild-type Arabidopsis plants, but the observed responses were not wavelength specific...
November 8, 2017: Experimental & Applied Acarology
https://www.readbyqxmd.com/read/29068175/micro-instillation-of-fluorescein-with-an-inoculation-loop-for-ocular-surface-staining-in-dry-eye-syndrome
#3
Emilie Courrier, Didier Renault, Mathilde Kaspi, Agathe Marcon, Victor Lambert, Thibaud Garcin, Frederic Chiambaretta, Gerhard Garhofer, Gilles Thuret, Philippe Gain
PURPOSE: To describe and validate the micro-instillation of fluorescein on the ocular surface by a disposable calibrated inoculation loop to improve corneal and conjunctival staining quality. METHODS: Accuracy and precision of the volume of 0.5% sodium fluorescein collected by a single use 1 μl-calibrated inoculation loop were measured using a precision balance. Twenty patients (40 eyes) suffering from dry eye syndrome were enrolled in a prospective interventional nonrandomized study...
October 25, 2017: Acta Ophthalmologica
https://www.readbyqxmd.com/read/29036694/efficient-modulation-of-photosynthetic-apparatus-confers-desiccation-tolerance-in-the-resurrection-plant-boea-hygrometrica
#4
Tinghong Tan, Yanni Sun, Shishuai Luo, Chao Zhang, Huapeng Zhou, Honghui Lin
Boea hygrometrica (B. hygrometrica) can tolerate severe desiccation and resume photosynthetic activity rapidly upon water availability. However, little is known about the mechanisms by which B. hygrometrica adapts to dehydration and resumes competence upon rehydration. Here we determine how B. hygrometrica deals with oxidative stress, excessive excitation/electron pressures as well as photosynthetic apparatus modulation during dehydration/rehydration. By measuring ROS generation and scavenging efficiency, we found that B...
November 1, 2017: Plant & Cell Physiology
https://www.readbyqxmd.com/read/28881133/localized-charges-control-exciton-energetics-and-energy-dissipation-in-doped-carbon-nanotubes
#5
Klaus H Eckstein, Holger Hartleb, Melanie M Achsnich, Friedrich Schöppler, Tobias Hertel
Doping by chemical or physical means is key for the development of future semiconductor technologies. Ideally, charge carriers should be able to move freely in a homogeneous environment. Here, we report on evidence suggesting that excess carriers in electrochemically p-doped semiconducting single-wall carbon nanotubes (s-SWNTs) become localized, most likely due to poorly screened Coulomb interactions with counterions in the Helmholtz layer. A quantitative analysis of blue-shift, broadening, and asymmetry of the first exciton absorption band also reveals that doping leads to hard segmentation of s-SWNTs with intrinsic undoped segments being separated by randomly distributed charge puddles approximately 4 nm in width...
October 24, 2017: ACS Nano
https://www.readbyqxmd.com/read/28879232/intracellular-spectral-recompositioning-of-light-enhances-algal-photosynthetic-efficiency
#6
Weiqi Fu, Amphun Chaiboonchoe, Basel Khraiwesh, Mehar Sultana, Ashish Jaiswal, Kenan Jijakli, David R Nelson, Ala'a Al-Hrout, Badriya Baig, Amr Amin, Kourosh Salehi-Ashtiani
Diatoms, considered as one of the most diverse and largest groups of algae, can provide the means to reach a sustainable production of petrochemical substitutes and bioactive compounds. However, a prerequisite to achieving this goal is to increase the solar-to-biomass conversion efficiency of photosynthesis, which generally remains less than 5% for most photosynthetic organisms. We have developed and implemented a rapid and effective approach, herein referred to as intracellular spectral recompositioning (ISR) of light, which, through absorption of excess blue light and its intracellular emission in the green spectral band, can improve light utilization...
September 2017: Science Advances
https://www.readbyqxmd.com/read/28773155/variation-of-structure-and-photoluminescence-properties-of-ce-3-doped-mgalon-transparent-ceramics-with-different-doping-content
#7
Xin Liu, Bowen Chen, Bingtian Tu, Hao Wang, Weimin Wang, Zhengyi Fu
Transparent MgAlON:Ce fluorescent ceramics with doping content of 0.005, 0.01, and 0.02 at % were fabricated by pressureless sintering. All the samples were dense and large in grain size. Under the excitation of 320 nm UV, the samples emitted blue lights centered around 410 nm. The 0.005 and 0.01 at % Ce(3+) doped samples were single phase by XRD detection, and possessed good optical and mechanical properties, and luminous thermal stability. The fluorescence lifetime, the CL and PL spectra analysis, indicated that most of the luminous centers were segregated in GB, and there was still a small part of second phase existing in 0...
July 13, 2017: Materials
https://www.readbyqxmd.com/read/28690558/blue-enriched-white-light-enhances-physiological-arousal-but-not-behavioral-performance-during-simulated-driving-at-early-night
#8
Beatriz Rodríguez-Morilla, Juan A Madrid, Enrique Molina, Angel Correa
Vigilance usually deteriorates over prolonged driving at non-optimal times of day. Exposure to blue-enriched light has shown to enhance arousal, leading to behavioral benefits in some cognitive tasks. However, the cognitive effects of long-wavelength light have been less studied and its effects on driving performance remained to be addressed. We tested the effects of a blue-enriched white light (BWL) and a long-wavelength orange light (OL) vs. a control condition of dim light on subjective, physiological and behavioral measures at 21:45 h...
2017: Frontiers in Psychology
https://www.readbyqxmd.com/read/28661438/macular-carotenoid-supplementation-improves-visual-performance-sleep-quality-and-adverse-physical-symptoms-in-those-with-high-screen-time-exposure
#9
James M Stringham, Nicole T Stringham, Kevin J O'Brien
The dramatic rise in the use of smartphones, tablets, and laptop computers over the past decade has raised concerns about potentially deleterious health effects of increased "screen time" (ST) and associated short-wavelength (blue) light exposure. We determined baseline associations and effects of 6 months' supplementation with the macular carotenoids (MC) lutein, zeaxanthin, and mesozeaxanthin on the blue-absorbing macular pigment (MP) and measures of sleep quality, visual performance, and physical indicators of excessive ST...
June 29, 2017: Foods (Basel, Switzerland)
https://www.readbyqxmd.com/read/28649427/global-rise-of-potential-health-hazards-caused-by-blue-light-induced-circadian-disruption-in-modern-aging-societies
#10
REVIEW
Megumi Hatori, Claude Gronfier, Russell N Van Gelder, Paul S Bernstein, Josep Carreras, Satchidananda Panda, Frederick Marks, David Sliney, Charles E Hunt, Tsuyoshi Hirota, Toshiharu Furukawa, Kazuo Tsubota
Mammals receive light information through the eyes, which perform two major functions: image forming vision to see objects and non-image forming adaptation of physiology and behavior to light. Cone and rod photoreceptors form images and send the information via retinal ganglion cells to the brain for image reconstruction. In contrast, nonimage-forming photoresponses vary widely from adjustment of pupil diameter to adaptation of the circadian clock. nonimage-forming responses are mediated by retinal ganglion cells expressing the photopigment melanopsin...
2017: NPJ Aging and Mechanisms of Disease
https://www.readbyqxmd.com/read/28559328/photoactivation-mechanism-of-a-carotenoid-based-photoreceptor
#11
Sepalika Bandara, Zhong Ren, Lu Lu, Xiaoli Zeng, Heewhan Shin, Kai-Hong Zhao, Xiaojing Yang
Photoprotection is essential for efficient photosynthesis. Cyanobacteria have evolved a unique photoprotective mechanism mediated by a water-soluble carotenoid-based photoreceptor known as orange carotenoid protein (OCP). OCP undergoes large conformational changes in response to intense blue light, and the photoactivated OCP facilitates dissipation of excess energy via direct interaction with allophycocyanins at the phycobilisome core. However, the structural events leading up to the OCP photoactivation remain elusive at the molecular level...
June 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28487255/disruption-of-adolescents-circadian-clock-the-vicious-circle-of-media-use-exposure-to-light-at-night-sleep-loss-and-risk-behaviors
#12
Yvan Touitou, David Touitou, Alain Reinberg
Although sleep is a key element in adolescent development, teens are spending increasing amounts of time online with health risks related to excessive use of electronic media (computers, smartphones, tablets, consoles…) negatively associated with daytime functioning and sleep outcomes. Adolescent sleep becomes irregular, shortened and delayed in relation with later sleep onset and early waking time due to early school starting times on weekdays which results in rhythm desynchronization and sleep loss. In addition, exposure of adolescents to the numerous electronic devices prior to bedtime has become a great concern because LEDs emit much more blue light than white incandescent bulbs and compact fluorescent bulbs and have therefore a greater impact on the biological clock...
May 12, 2017: Journal of Physiology, Paris
https://www.readbyqxmd.com/read/28472717/photoreceptor-dependent-regulation-of-photoprotection
#13
REVIEW
Guillaume Allorent, Dimitris Petroutsos
In photosynthetic organisms, proteins in the light-harvesting complex (LHC) harvest light energy to fuel photosynthesis, whereas photoreceptor proteins are activated by the different wavelengths of the light spectrum to regulate cellular functions. Under conditions of excess light, blue-light photoreceptors activate chloroplast avoidance movements in sessile plants, and blue- and green-light photoreceptors cause motile algae to swim away from intense light. Simultaneously, LHCs switch from light-harvesting mode to energy-dissipation mode, which was thought to be independent of photoreceptor-signaling up until recently...
May 1, 2017: Current Opinion in Plant Biology
https://www.readbyqxmd.com/read/28419325/dissecting-molecular-and-physiological-response-mechanisms-to-high-solar-radiation-in-cyanic-and-acyanic-leaves-a-case-study-on-red-and-green-basil
#14
Massimiliano Tattini, Federico Sebastiani, Cecilia Brunetti, Alessio Fini, Sara Torre, Antonella Gori, Mauro Centritto, Francesco Ferrini, Marco Landi, Lucia Guidi
Photosynthetic performance and the expression of genes involved in light signaling and the biosynthesis of isoprenoids and phenylpropanoids were analysed in green ('Tigullio', TIG) and red ('Red Rubin', RR) basil. The aim was to detect the physiological and molecular response mechanisms to high sunlight. The attenuation of blue-green light by epidermal anthocyanins was shown to evoke shade-avoidance responses with consequential effects on leaf morpho-anatomical traits and gas exchange performance. Red basil had a lower mesophyll conductance, partially compensated by the less effective control of stomatal movements, in comparison with TIG...
April 1, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28392641/low-level-light-therapy-with-410-nm-light-emitting-diode-suppresses-collagen-synthesis-in-human-keloid-fibroblasts-an-in-vitro-study
#15
Hyun Soo Lee, Soo-Eun Jung, Sue Kyung Kim, You-Sun Kim, Seonghyang Sohn, You Chan Kim
BACKGROUND: Keloids are characterized by excessive collagen deposition in the dermis, in which transforming growth factor β (TGF-β)/Smad signaling plays an important role. Low-level light therapy (LLLT) is reported as effective in preventing keloids in clinical reports, recently. To date, studies investigating the effect of LLLT on keloid fibroblasts are extremely rare. OBJECTIVE: We investigated the effect of LLLT with blue (410 nm), red (630 nm), and infrared (830 nm) light on the collagen synthesis in keloid fibroblasts...
April 2017: Annals of Dermatology
https://www.readbyqxmd.com/read/28391046/structure-and-functions-of-orange-carotenoid-protein-homologs-in-cyanobacteria
#16
REVIEW
Han Bao, Matthew R Melnicki, Cheryl A Kerfeld
Rapidly-induced photoprotection in cyanobacteria involves thermal dissipation of excess energy absorbed by the phycobilisome (PBS), the primary light-harvesting antenna. This process is called non-photochemical quenching (NPQ), and is mediated by a water-soluble photoactive protein, the Orange Carotenoid Protein (OCP). The OCP is structurally and functionally modular, consisting of a sensor domain, an effector domain, and a carotenoid. Blue-green light induces a structural transition of the OCP from the orange inactive form, OCP(o), to the red active form, OCP(R)...
April 5, 2017: Current Opinion in Plant Biology
https://www.readbyqxmd.com/read/28325907/photosensitization-of-tio2-nanofibers-by-ag2s-with-the-synergistic-effect-of-excess-surface-ti-3-states-for-enhanced-photocatalytic-activity-under-simulated-sunlight
#17
Samina Ghafoor, Sadia Ata, Nasir Mahmood, Salman Noshear Arshad
TiO2 nanofibers, with mean diameter ~200 nm, were fabricated by electrospinning and successfully photosensitized with low bandgap Ag2S nanoparticles of 11, 17, 23 and 40 nm mean sizes, with corresponding loading of 4, 10, 18 and 29 wt.% Ag2S, respectively. 17 nm Ag2S@TiO2 nanofibers exhibited optimal activity in the photodegradation of methylene blue under simulated sunlight with pseudo-first order rate constant of 0.019 min(-1) compared to 0.009 min(-1) for pure TiO2 nanofibers. In spite of greater visible-light absorption and reduced bandgap, larger than 17 nm Ag2S nanoparticles exhibited sluggish photodegradation kinetics probably due to less photo-induced carriers generation in TiO2 and reduced electron injection rates from the larger sized Ag2S into TiO2...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28317022/water-dispersible-silica-coated-upconverting-liposomes-can-a-thin-silica-layer-protect-tta-uc-against-oxygen-quenching
#18
Sven H C Askes, Vincent C Leeuwenburgh, Wim Pomp, Hadi Arjmandi-Tash, Stefania Tanase, Thomas Schmidt, Sylvestre Bonnet
Light upconversion by triplet-triplet annihilation (TTA-UC) in nanoparticles has received considerable attention for bioimaging and light activation of prodrugs. However, the mechanism of TTA-UC is inherently sensitive for quenching by molecular oxygen. A potential oxygen protection strategy is the coating of TTA-UC nanoparticles with a layer of oxygen-impermeable material. In this work, we explore if (organo)silica can fulfill this protecting role. Three synthesis routes are described for preparing water-dispersible (organo)silica-coated red-to-blue upconverting liposomes...
March 13, 2017: ACS Biomaterials Science & Engineering
https://www.readbyqxmd.com/read/28240871/photoinduced-stark-effects-and-mechanism-of-ion-displacement-in-perovskite-solar-cell-materials
#19
Meysam Pazoki, T Jesper Jacobsson, Jolla Kullgren, Erik M J Johansson, Anders Hagfeldt, Gerrit Boschloo, Tomas Edvinsson
Organometallic halide perovskites (OMHPs) have recently emerged as a promising class of materials in photovoltaic technology. Here, we present an in-depth investigation of the physics in these systems by measuring the photoinduced absorption (PIA) in OMHPs as a function of materials composition, excitation wavelength, and modulation frequency. We report a photoinduced Stark effect that depends on the excitation wavelength and on the dipole strength of the monovalent cations in the A position of the ABX3 perovskite...
March 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28236074/interaction-of-the-signaling-state-analog-and-the-apoprotein-form-of-the-orange-carotenoid-protein-with-the-fluorescence-recovery-protein
#20
Marcus Moldenhauer, Nikolai N Sluchanko, Neslihan N Tavraz, Cornelia Junghans, David Buhrke, Mario Willoweit, Leonardo Chiappisi, Franz-Josef Schmitt, Vladana Vukojević, Evgeny A Shirshin, Vladimir Y Ponomarev, Vladimir Z Paschenko, Michael Gradzielski, Eugene G Maksimov, Thomas Friedrich
Photoprotection in cyanobacteria relies on the interplay between the orange carotenoid protein (OCP) and the fluorescence recovery protein (FRP) in a process termed non-photochemical quenching, NPQ. Illumination with blue-green light converts OCP from the basic orange state (OCP(O)) into the red-shifted, active state (OCP(R)) that quenches phycobilisome (PBs) fluorescence to avoid excessive energy flow to the photosynthetic reaction centers. Upon binding of FRP, OCP(R) is converted to OCP(O) and dissociates from PBs; however, the mode and site of OCP(R)/FRP interactions remain elusive...
February 24, 2017: Photosynthesis Research
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