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Light : the visible spectrum and beyond
A visual exploration of the power and behavior of light across the entire electromagnetic spectrum reveals how types ranging from radio waves to X-rays affect life on earth and throughout the universe. --Publisher.
Book
A blue-light photoreceptor mediates the feedback regulation of photosynthesis
Algae rely on blue-light-sensitive phototropin to trigger induction of LHCRS3, allowing it to dissipate energy from excess light that would otherwise compromise the fitness of the organism.
Phototropin mediates photosynthesis regulation
Excessive light can overwhelm the photosynthetic system of plants and algae, leading to damage or even cell death. Consequently, plants have evolved systems to prevent such overload. Giovanni Finazzi and colleagues demonstrate that, in the green alga
Chlamydomonas reinhardtii
, the blue-light photoreceptor phototropin (PHOT) induces the expression of light-harvesting complex stress-related protein 3 (LHCSR3) when light levels are sufficiently high. This causes the dissipation of excess light from photosystem II. In the absence of PHOT activity, the fitness of the algae is severely compromised.
In plants and algae, light serves both as the energy source for photosynthesis and a biological signal that triggers cellular responses via specific sensory photoreceptors. Red light is perceived by bilin-containing phytochromes and blue light by the flavin-containing cryptochromes and/or phototropins (PHOTs)
1
, the latter containing two photosensory light, oxygen, or voltage (LOV) domains
2
. Photoperception spans several orders of light intensity
3
, ranging from far below the threshold for photosynthesis to values beyond the capacity of photosynthetic CO
2
assimilation. Excess light may cause oxidative damage and cell death, processes prevented by enhanced thermal dissipation via high-energy quenching (qE), a key photoprotective response
4
. Here we show the existence of a molecular link between photoreception, photosynthesis, and photoprotection in the green alga
Chlamydomonas reinhardtii.
We show that PHOT controls qE by inducing the expression of the qE effector protein LHCSR3 (light-harvesting complex stress-related protein 3) in high light intensities. This control requires blue-light perception by LOV domains on PHOT, LHCSR3 induction through PHOT kinase, and light dissipation in photosystem II via LHCSR3. Mutants deficient in the
PHOT
gene display severely reduced fitness under excessive light conditions, indicating that the sensing, utilization, and dissipation of light is a concerted process that plays a vital role in microalgal acclimation to environments of variable light intensities.
Journal Article
Light
\"In this book, young readers will discover interesting facts about light, and discover a variety of fun experiments to test their knowledge.\"-- Provided by publisher.
Book
Sources of light
Takes a look at sources of light, and explains the difference between things that make light and things that don't.
Book
255 Spectrophotometric Properties of Commercial Blue-Blocking Lenses in Sunlight
Introduction Blue-blocking glasses are increasingly used as an intervention for jet-lag and other situations where an individual wishes to promote a “dark” signal despite the presence of ambient light. However, most studies on blue-blockers are done under controlled laboratory settings using emissions generated from electric light sources. The present study evaluated the performance of commercially available blue-blockers under daytime sunlight conditions. Methods A calibrated spectroradiometer (Ocean Insight), cosine corrector, optic fiber, and software package were used to measure the absolute irradiance (uW/cm^2/nm) available midday in a standardized location that received direct sunlight. Thirty-one commercially available blue-blockers were individually placed in front of the cosine corrector and intensity was measured and analyzed. Each lens was tested for its ability to block visible light, as well as light within the 440-530nm range. Lenses were evaluated individually and grouped by lens type: red-tinted lenses (RTL), orange-tinted lenses (ORL), orange-tinted lenses with blue reflectivity (OBL), brown-tinted lenses (BTL), yellow-tinted lenses (YTL), and clear lenses with blue reflectivity (RBL). Results Across the full spectrum, RTL blocked 66% of the light, OTL blocked 60%, OBL blocked 43%, BTL blocked 56%, YTL blocked 28%, and RBL blocked 20%. When the range was restricted to 440-530nm, RTL blocked 99%, OTL blocked 96%, OBL blocked 90%, BTL blocked 66%, YTL blocked 38%, and RBL blocked 17% of the light. Variation across lens types was significant for the full spectrum (one-way ANOVA, p < 0.0001) as well as the 440-530nm range (one-way ANOVA, p < 0.0001). Individual lenses showed variability in performance, though this variability was smaller than the between-group differences. Conclusion Under daylight conditions, red and orange lenses (RTL, OTL, and OBL) blocked at least 90% of the light in the 440-530nm range. Notably, RBL lenses restricted the most short-wavelength light as a proportion of the total light blocked. These data suggest that RTL, OTL, and OBL are effective at blocking the most circadian photosensitive components of daylight at the cost of reducing total illumination. Support (if any) R01MD011600, R01DA051321
Journal Article
Light show
\"Light Show explores how artists working over the past fifty years have used that power to create some of the most innovative and compelling sculpture in contemporary art.\"--Page 4 of cover.
Book
Plasmonic Nanodomains Decorated on Two-Dimensional Oxide Semiconductors for Photonic-Assisted COsub.2 Conversion
Plasmonic nanostructures ensure the reception and harvesting of visible lights for novel photonic applications. In this area, plasmonic crystalline nanodomains decorated on the surface of two-dimensional (2D) semiconductor materials represent a new class of hybrid nanostructures. These plasmonic nanodomains activate supplementary mechanisms at material heterointerfaces, enabling the transfer of photogenerated charge carriers from plasmonic antennae into adjacent 2D semiconductors and therefore activate a wide range of visible-light assisted applications. Here, the controlled growth of crystalline plasmonic nanodomains on 2D Ga[sub.2]O[sub.3] nanosheets was achieved by sonochemical-assisted synthesis. In this technique, Ag and Se nanodomains grew on 2D surface oxide films of gallium-based alloy. The multiple contribution of plasmonic nanodomains enabled the visible-light-assisted hot-electron generation at 2D plasmonic hybrid interfaces, and therefore considerably altered the photonic properties of the 2D Ga[sub.2]O[sub.3] nanosheets. Specifically, the multiple contribution of semiconductor-plasmonic hybrid 2D heterointerfaces enabled efficient CO[sub.2] conversion through combined photocatalysis and triboelectric-activated catalysis. The solar-powered acoustic-activated conversion approach of the present study enabled us to achieve the CO[sub.2] conversion efficiency of more than 94% in the reaction chambers containing 2D Ga[sub.2]O[sub.3]-Ag nanosheets.
Journal Article
Investigating light
\"Budding scientists will love learning about the properties of light by planning and carrying out investigations that explore how the energy form can be reflected, manipulated, and refracted.\"-- Provided by publisher.
Book
Daratumumab-Based Treatment for Immunoglobulin Light-Chain Amyloidosis
In a randomized trial of bortezomib, cyclophosphamide, and dexamethasone as compared with the same therapy plus daratumumab, patients with light-chain amyloidosis who received daratumumab had a higher frequency of hematologic complete response than those who did not (53.3% vs. 18.1%). Deaths were most commonly due to cardiac failure.
Journal Article