Different Colors Of Light Research Articles

Light‐Controlled, High‐Resolution Patterning of Living Engineered Bacteria Onto Textiles, Ceramics, and Plastic

AbstractLiving cells can impart materials with advanced functions, such as sense‐and‐respond, chemical production, toxin remediation, energy generation and storage, self‐destruction, and self‐healing. Here, an approach is presented to use light to pattern Escherichia coli onto diverse materials by controlling the expression of curli fibers that anchor the formation of a biofilm. Different colors of light are used to express variants of the structural protein CsgA fused to different peptide tags. By projecting color images onto the material containing bacteria, this system can be used to pattern the growth of composite materials, including layers of protein and gold nanoparticles. This is used to pattern cells onto materials used for 3D printing, plastics (polystyrene), and textiles (cotton). Further, the adhered cells are demonstrated to respond to sensory information, including small molecules (IPTG and DAPG) and light from light‐emitting diodes. This work advances the capacity to engineer responsive living materials in which cells provide diverse functionality.

Development and Characterization of An Injury-free Model of Functional Pain in Rats by Exposure to Red Light

We report the development and characterization of a novel, injury-free rat model in which nociceptive sensitization after red light is observed in multiple body areas reminiscent of widespread pain in functional pain syndromes. Rats were exposed to red light-emitting diodes (RLED) (LEDs, 660 nm) at an intensity of 50 Lux for 8 hours daily for 5 days resulting in time- and dose-dependent thermal hyperalgesia and mechanical allodynia in both male and female rats. Females showed an earlier onset of mechanical allodynia than males. The pronociceptive effects of RLED were mediated through the visual system. RLED-induced thermal hyperalgesia and mechanical allodynia were reversed with medications commonly used for widespread pain, including gabapentin, tricyclic antidepressants, serotonin/norepinephrine reuptake inhibitors, and nonsteroidal anti-inflammatory drugs. Acetaminophen failed to reverse the RLED induced hypersensitivity. The hyperalgesic effects of RLED were blocked when bicuculline, a gamma-aminobutyric acid-A receptor antagonist, was administered into the rostral ventromedial medulla, suggesting a role for increased descending facilitation in the pain pathway. Key experiments were subjected to a replication study with randomization, investigator blinding, inclusion of all data, and high levels of statistical rigor. RLED-induced thermal hyperalgesia and mechanical allodynia without injury offers a novel injury-free rodent model useful for the study of functional pain syndromes with widespread pain. RLED exposure also emphasizes the different biological effects of different colors of light exposure. PerspectiveThis study demonstrates the effect of light exposure on nociceptive thresholds. These biological effects of red LED add evidence to the emerging understanding of the biological effects of light of different colors in animals and humans. Understanding the underlying biology of red light-induced widespread pain may offer insights into functional pain states.

Light-Triggered Boost of Activity of Catalytic Bola-Type Surfactants by a Plasmonic Metal-Support Interaction Effect.

The maximization of activity is a general aim in catalysis research. The possibility for light-triggered enhancement of a catalytic process, even if the process is not photochemical in nature, represents an intriguing concept. Here, we present a novel system for the exploration of the latter idea. A surfactant with a catalytically active head group, a protonated polyoxometalate (POM) cluster, is attached to the surface of a gold nanoparticle (Au NP) using thiol coupling chemistry. The distance of the catalytically active center to the gold surface could be adjusted precisely using surfactants containing hydrocarbon chains (Cn) of different lengths (n = 4–10). Radiation with VIS-light has no effect on the catalytic activity of micellar aggregates of the surfactant. The situation changes, as soon as the surfactants have been attached to the Au NPs. The catalytic activity could almost be doubled. It was proven that the effect is caused by coupling the surface plasmon resonance of the Au NPs with the properties of the POM head group. The improvement of activity could only be observed if the excitation wavelength matches the absorption band of the used Au NPs. Furthermore, the shorter the distance between the POM group and the surface of the NP, the stronger is the effect. This phenomenon was explained by lowering the activation energy of the transition state relevant to the catalytic process by the strong electric fields in the vicinity of the surfaces of plasmonic nanoparticles. Because the catalytic enhancement is wavelength-selective, one can imagine the creation of complex systems in the future, a system of differently sized NPs, each responsible for a different catalytic step and activated by light of different colors.

Attraction of nocturnally migrating birds to artificial light: The influence of colour, intensity and blinking mode under different cloud cover conditions

A growing number of offshore wind farms have led to a tremendous increase in artificial lighting in the marine environment. This study disentangles the connection of light characteristics, which potentially influence the reaction of nocturnally migrating passerines to artificial illumination under different cloud cover conditions. In a spotlight experiment on a North Sea island, birds were exposed to combinations of light colour (red, yellow, green, blue, white), intensity (half, full) and blinking mode (intermittent, continuous) while measuring their number close to the light source with thermal imaging cameras.We found that no light variant was constantly avoided by nocturnally migrating passerines crossing the sea. The number of birds did neither differ between observation periods with blinking light of different colours nor compared to darkness. While intensity did not influence the number attracted, birds were drawn more towards continuous than towards blinking illumination, when stars were not visible. Red continuous light was the only exception that did not differ from the blinking counterpart. Continuous green, blue and white light attracted significantly more birds than continuous red light in overcast situations.Our results suggest that light sources offshore should be restricted to a minimum, but if lighting is needed, blinking light is to be preferred over continuous light, and if continuous light is required, red light should be applied.

On the fundamental mechanism of multicolor light generation from Y2O3:Dy3+/Eu3+ nanocrystal

Nanomaterials possess attractive properties which their bulk counterparts do not have. Generation of different colors of light by changing size and/or composition of nanomaterials are well established. Further, there are plethora of reports on dissemination of different properties from an individual nanomaterial. However, fundamental mechanisms leading to multicolor light generation from a nanocrystalline sample are seldom reported. In this work, three different colors of light are tuned from a single sample of Y2O3:Dy3+/Eu3+ nanocrystal. Its fundamental mechanism is proposed on the basis of Förster resonance energy transfers. Photoluminescence energy transfer mechanisms leading to the different colors are also elucidated. Our work opens up research on fundamental mechanisms for a class of materials which can generate multicolors of light from a single sample. This multicolour light generating nanocrystal has potential in the field of multicolor display, security printing, sensor, etc.

Effect of different colours of light as night break on growth and flowering of chrysanthemum (Chrysanthemum morifolium Ramat.) Genotypes

Effect of different colours of light as night break on growth and flowering of chrysanthemum (<i>Chrysanthemum morifolium</i> Ramat.) Genotypes

Fully independent photochemical reactivity in one molecule.

We introduce a chemically λ-orthogonal bichromophore triggered simply by different colours of light, enabling two different photochemical reactions in one molecule. Uniquely, the short wavelength (λ = 314 nm) does not trigger the red-shifted reaction system (λ = 416 nm), opening possibilities for the light controlled gating of specific molecular sites independent of wavelength.

不同颜色光照对土壤养分活化过程研究

不同颜色光照对土壤养分活化过程研究

The migraine eye: distinct rod-driven retinal pathways' response to dim light challenges the visual cortex hyperexcitability theory

Migraine-type photophobia, most commonly described as exacerbation of headache by light, affects nearly 90% of the patients. It is the most bothersome symptom accompanying an attack. Using subjective psychophysical assessments, we showed that migraine patients are more sensitive to all colors of light during ictal than during interictal phase and that control subjects do not experience pain when exposed to different colors of light. Based on these findings, we suggested that color preference is unique to migraineurs (as it was not found in control subjects) rather than migraine phase (as it was found in both phases). To identify the origin of this photophobia in migraineurs, we compared the electrical waveforms that were generated in the retina and visual cortex of 46 interictal migraineurs to those generated in 42 healthy controls using color-based electroretinography and visual-evoked potential paradigms. Unexpectedly, it was the amplitude of the retinal rod-driven b wave, which was consistently larger (by 14%-19% in the light-adapted and 18%-34% in the dark-adapted flash ERG) in the migraineurs than in the controls, rather than the retinal cone-driven a wave or the visual-evoked potentials that differs most strikingly between the 2 groups. Mechanistically, these findings suggest that the inherent hypersensitivity to light among migraine patients may originate in the retinal rods rather than retinal cones or the visual cortex. Clinically, the findings may explain why migraineurs complain that the light is too bright even when it is dim to the extent that nonmigraineurs feel as if they are in a cave.

An experimental study on fish attraction using a fish barge model

Fish-collection and transportation systems (FCTS) have been introduced and applied as innovative approaches to facilitate fish passage in China for several years. The efficacy of FCTSs depends directly on the efficiency of the fish-guidance measures employed. In this study, the effects of three parameters—water flow, artificial lighting, and bubble curtains—on the attraction of mosquitofish (Gambusia affinis) was investigated using a fish barge model in a large pond. The experiment was conducted in two steps. First, a univariate experiment was performed, and then, a multivariate experiment using an orthogonal design was performed. Four different colors of light were tested: 1) yellow light (570 nm), 2) blue light (460 nm), 3) warm white light (3000 K), and 4) a weak light control group, whose illuminance belongs to the interval 0.001 lx to 0.3 lx. Supplementing water flow within the barge decreased the number of attracted fish (i.e., the number of the targeted fish species that appeared within 1.5 m of the barge model’s entrance) but increased the fish-collection ratio of the fish-collecting platform (i.e., the ratio of the number of attracted fish to the number of collected fish). Warm white light was shown to be significantly effective in attracting fish, while no obvious effect was observed in terms of the fish-collection ratio. The bubble curtain exhibited excellent fish-attraction efficacies, but also had no significant effect on the attraction and collection efficacy of the fish-collecting platform. During the day, the optimal combination for fish attraction was to have no water flow with a bubble curtain, while the optimal combination for fish collection was to have no water flow and no bubble curtain. During the night, the optimal combination for fish attraction was to have no water flow, no bubble curtain, and a warm white light, while the optimal combination for fish collection was to have water flow, no bubble curtain, and a weak light. This study tested the combined efficacies of various fish-guidance measures on a fish-collecting platform, thus providing experimental support for optimizing various fish-attraction measures and the application of these measures in FCTS projects.

Femtosecond laser fabricated polymeric grating for spectral tuning

By taking advantages of the two-photon polymerization induced by femtosecond laser and the versatility of the femtosecond laser microfabrication, we demonstrate a femtosecond laser microfabricated polymeric grating for spectral tuning, in which gratings of different thicknesses achieve gradual tuning of a white incident light into output lights of different colors ranging from cyan to red, which is in good agreement with the simulation. Through the selection of different grating parameters, the technique developed in this study offers the possibility to tailor the performance of the grating to achieve specific grating efficiency or complete extinction at specific wavelengths, which is promising for measurements and applications in spectroscopy, sensing, integrated optical systems, and biomedicine.

Beetle luciferases with naturally red- and blue-shifted emission.

The different colors of light emitted by bioluminescent beetles that use an identical substrate and chemiexcitation reaction sequence to generate light remain a challenging and controversial mechanistic conundrum. The crystal structures of two beetle luciferases with red- and blue-shifted light relative to the green yellow light of the common firefly species provide direct insight into the molecular origin of the bioluminescence color. The structure of a blue-shifted green-emitting luciferase from the firefly Amydetes vivianii is monomeric with a structural fold similar to the previously reported firefly luciferases. The only known naturally red-emitting luciferase from the glow-worm Phrixothrix hirtus exists as tetramers and octamers. Structural and computational analyses reveal varying aperture between the two domains enclosing the active site. Mutagenesis analysis identified two conserved loops that contribute to the color of the emitted light. These results are expected to advance comparative computational studies into the conformational landscape of the luciferase reaction sequence.

Color-selective photophobia in ictal vs interictal migraineurs and in healthy controls.

Aversion to light is common among migraineurs undergoing acute attacks. Using psychophysical assessments in patients with episodic migraine, we reported that white, blue, amber, and red lights exacerbate migraine headache in a significantly larger percentage of patients and to a greater extent compared with green light. This study aimed at determining whether these findings are phase-dependent-namely, manifested exclusively during migraine (ictally) but not in its absence (interictally), or condition-dependent-ie, expressed uniquely in migraineurs but not in healthy controls. To determine whether the color preference of migraine-type photophobia is phase- or condition-dependent, we compared the effects of each color of light in each intensity between migraineurs during and in-between attacks and healthy controls. During the ictal and interictal phases, the proportion of migraineurs reporting changes in headache severity when exposed to the different colors of light increased in accordance with elevated light intensities. During the ictal phase, white, blue, amber, and red lights exacerbated headaches in ∼80% of the patients; however, during the interictal phase, light initiated headache in only 16% to 19%. Notably, green light exacerbated headaches in 40% and triggered headaches in 3% of the patients studied during the ictal and interictal phases, respectively. With one exception (highest red light intensity), no control subject reported headache in response to the light stimuli. These findings suggest that color preference is unique to migraineurs-as it was not found in control subjects-and that it is independent of whether or not the patients are in their ictal or interictal phase.

Color‐Sensitive Ultrafast Optical Modulation and Switching of Terahertz Plasmonic Devices

Abstract2D micro‐nanostructured metal films with hole arrays show promising features such as the extraordinary transmission of light. Such systems are interesting in the field of subwavelength photonics and nonlinear optics due to their high field confinement in addition to their inherent spectral scalability and frequency selective response. Several active schemes to control the extraordinary transmission are recently demonstrated. However, these dynamic devices do not reveal any obvious color‐dependent modulation of the resonant transmission behavior. Here, color‐sensitive ultrafast modulation of extraordinary resonant transmission of terahertz (THz) waves through 2D metallic hole arrays is demonstrated. Pumping the silicon beneath the metallic array with light of different colors and identical fluences exhibit significantly different ultrafast switching dynamics and modulation. The color‐dependent sensitivity and control of THz waves at an ultrafast timescale provide an extra degree of freedom that opens up new opportunities for future applications in active subwavelength optics, optoelectronics, and all‐optical switching of THz photonic devices.

Enhanced Electron Injection and Exciton Confinement for Pure Blue Quantum-Dot Light-Emitting Diodes by Introducing Partially Oxidized Aluminum Cathode

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation displays and solid-state lighting technologies. The brightness and efficiency of blue QDs-based light-emitting diodes (LEDs) remain inferior to their red and green counterparts, due to the inherently unfavorable energy levels of different colors of light. To solve these problems, a device structure should be designed to balance the injection holes and electrons into the emissive QD layer. Herein, through a simple autoxidation strategy, pure blue QD-LEDs which are highly bright and efficient are demonstrated, with a structure of ITO/PEDOT:PSS/Poly-TPD/QDs/Al:Al2O3. The autoxidized Al:Al2O3 cathode can effectively balance the injected charges and enhance radiative recombination without introducing an additional electron transport layer (ETL). As a result, high color-saturated blue QD-LEDs are achieved with a maximum luminance over 13,000 cd m-2, and a maximum current efficiency of 1.15 cd A-1. The easily controlled autoxidation procedure paves the way for achieving high-performance blue QD-LEDs.

No effect of artificial light of different colors on commuting Daubenton's bats (Myotis daubentonii) in a choice experiment.

Progressive illumination at night poses an increasing threat to species worldwide. Light at night is particularly problematic for bats as most species are nocturnal and often cross relatively large distances when commuting between roosts and foraging grounds. Earlier studies have shown that illumination of linear structures in the landscape disturbs commuting bats, and that the response of bats to light may strongly depend on the light spectrum. Here, we studied the impact of white, green, and red light on commuting Daubenton's bats (Myotis daubentonii). We used a unique location where commuting bats cross a road by flying through two identical, parallel culverts underneath. We illuminated the culverts with white, red, and green light, with an intensity of 5 lux at the water surface. Bats had to choose between the two culverts, each with a different lighting condition every night. We presented all paired combinations of white, green, and red light and dark control in a factorial design. Contrary to our expectations, the number of bat passes through a culvert was unaffected by the presence of light. Furthermore, bats did not show any preference for light color. These results show that the response of commuting Daubenton's bats to different colors of light at night with a realistic intensity may be limited when passing through culverts.

Visio-Vestibular Interaction in Humans: Changes in the Vestibular Response Following Visual Stimuli of Different Colors

This paper addresses the question of whether visual stimuli of different colors can evoke a measurable vestibular response. A recently developed technique of measuring the vestibular response, called electrovestibulography (EVestG), was used in this study to assess the responsiveness of the efferent vestibular system. Visual stimuli of different colors (blue, green and red lights) along with white and black background were displayed to the participants through a virtual reality (VR) headset. Initially, the effect of each color was investigated; for each color, the corresponding red, green, or blue (RGB) value was set to 255 and the two others set to zero. Additionally, for the blue light, the impact of the intensity under well-lit (photopic) and low (close to mesopic vision range) intensity levels was separately examined. The results of this study indicate that not only does the vestibular system respond to light of different colors, but it also shows a sensitivity to the intensity of blue light. For blue light, the vestibular response changed in proportion to the intensity level, showing larger responses at higher intensities.

From E to Z and back again: reversible photoisomerisation of an isolated charge-tagged azobenzene.

Substituted azobenzenes serve as chromophores and actuators in a wide range of molecular photoswitches. Here, tandem ion mobility spectrometry coupled with laser excitation is used to investigate the photoisomerisation of selected E and Z isomers of the charge-tagged azobenzene, methyl orange. Both isomers display a weak S1(nπ*) photoisomerisation response in the blue part of the spectrum peaking at 440 nm and a more intense S2(ππ*) photoisomerisation response in the near-UV with maxima at 370 and 310 nm for the E and Z isomers, respectively. The 60 nm separation between the S2(ππ*) photo-response maxima for the two isomers allows them to be separately addressed in the gas phase and to be reversibly photoisomerised using different colours of light. This is an essential characteristic of an ideal photoswitch. The study demonstrates that a sequence of light pulses at different stages in an ion mobility spectrometer can be deployed to generate and probe isomers that cannot be electrosprayed directly from solution or produced through collisions in the ion source.

Controlling thermal reactivity with different colors of light

The ability to switch between thermally and photochemically activated reaction channels with an external stimulus constitutes a key frontier within the realm of chemical reaction control. Here, we demonstrate that the reactivity of triazolinediones, powerful coupling agents in biomedical and polymer research, can be effectively modulated by an external photonic field. Specifically, we show that their visible light-induced photopolymerization leads to a quantitative photodeactivation, thereby providing a well-defined off-switch of their thermal reactivity. Based on this photodeactivation, we pioneer a reaction manifold using light as a gate to switch between a UV-induced Diels–Alder reaction with photocaged dienes and a thermal addition reaction with alkenes. Critically, the modulation of the reactivity by light is reversible and the individually addressable reaction pathways can be repeatedly accessed. Our approach thus enables a step change in photochemically controlled reactivity, not only in small molecule ligations, yet importantly in controlled surface and photoresist design.

Effect of short-term colored-light exposure on cerebral hemodynamics and oxygenation, and systemic physiological activity.

.There is not yet a comprehensive view of how the color of light affects the cerebral and systemic physiology in humans. The aim was to address this deficit through basic research. Since cerebral and systemic physiological parameters are likely to interact, it was necessary to establish an approach, which we have termed “systemic-physiology-augmented functional near-infrared spectroscopy (SPA-fNIRS) neuroimaging.” This multimodal approach measures the systemic and cerebral physiological response to exposure to light of different colors. In 14 healthy subjects (9 men, 5 women, age: years, range: 24 to 57 years) exposed to red, green, and blue light (10-min intermittent wide-field visual color stimulation; blocks of visual stimulation), brain hemodynamics and oxygenation were measured by fNIRS on the prefrontal cortex (PFC) and visual cortex (VC) simultaneously, in addition with systemic parameters. This study demonstrated that (i) all colors elicited responses in the VC, whereas only blue evoked a response in the PFC; (ii) there was a color-dependent effect on cardiorespiratory activity; (iii) there was significant change in neurosystemic functional connectivity; (iv) cerebral hemodynamic responses in the PFC and changes in the cardiovascular system were gender and age dependent; and (v) electrodermal activity and psychological state showed no stimulus-evoked changes, and there was no dependence on color of light, age, and gender. We showed that short-term light exposure caused color-dependent responses in cerebral hemodynamics/oxygenation as well as cardiorespiratory dynamics. Additionally, we showed that neurosystemic functional connectivity changes even during apparently stress-free tasks—an important consideration when using any of the hemodynamic neuroimaging methods (e.g. functional magnetic resonance imaging, positron emission tomography, and fNIRS). Our findings are important for future basic research and clinical applications as well as being relevant for everyday life.