Different Colors Of Light Research Articles

Inorganic Phosphor Materials for Lighting.

This chapter addresses the development of inorganic phosphor materials capable of converting the near UV or blue radiation emitted by a light emitting diode to visible radiation that can be suitably combined to yield white light. These materials are at the core of the new generation of solid-state lighting devices that are emerging as a crucial clean and energy saving technology. The chapter introduces the problem of white light generation using inorganic phosphors and the structure-property relationships in the broad class of phosphor materials, normally containing lanthanide or transition metal ions as dopants. Radiative and non-radiative relaxation mechanisms are briefly described. Phosphors emitting light of different colors (yellow, blue, green, and red) are described and reviewed, classifying them in different chemical families of the host (silicates, phosphates, aluminates, borates, and non-oxide hosts). This research field has grown rapidly and is still growing, but the discovery of new phosphor materials with optimized properties (in terms of emission efficiency, chemical and thermal stability, color, purity, and cost of fabrication) would still be of the utmost importance.

Impact of light color on photobioreactor productivity

Microalgae perform photosynthesis at a high efficiency under low light conditions. However, under bright sunlight, it is difficult to achieve a high photosynthetic efficiency, because cells absorb more light energy than can be converted to biochemical energy. Consequently microalgae dissipate part of the absorbed light energy as heat. The objective of this study was to investigate photobioreactor productivity as a function of the biomass specific light absorption rate. A strategy to circumvent oversaturation is to exploit light with a spectral composition that minimizes light absorption. We studied productivity of Chlamydomonas reinhardtii cultivated under different colors of light. The incident light intensity was 1500μmolphotonsm−2s−1, and cultivation took place in turbidostat controlled lab-scale panel photobioreactors. Our results demonstrate that, under mass culture conditions, productivity and biomass specific light absorption are inversely correlated. The highest productivity, measured under continuous illumination, was obtained using yellow light (54gm−2d−1) while blue and red light resulted in the lowest light use efficiency (29gm−2d−1). Presumed signs of biological interference caused by employing monochromatic light of various wavelengths are discussed. This study provides a base for different approaches to maximize productivity by lowering the biomass specific light absorption rate.

An inexpensive programmable illumination microscope with active feedback

We have developed a programmable illumination system capable of tracking and illuminating numerous objects simultaneously using only low-cost and reused optical components. The active feedback control software allows for a closed-loop system that tracks and perturbs objects of interest automatically. Our system uses a static stage where the objects of interest are tracked computationally as they move across the field of view allowing for a large number of simultaneous experiments. An algorithmically determined illumination pattern can be applied anywhere in the field of view with simultaneous imaging and perturbation using different colors of light to enable spatially and temporally structured illumination. Our system consists of a consumer projector, camera, 35-mm camera lens, and a small number of other optical and scaffolding components. The entire apparatus can be assembled for under $4,000.

Effects of Light Color on Consumers’ Acceptability and Willingness to Eat Apples and Bell Peppers

AbstractThis study aimed to determine whether ambient light colors affect consumers’ willingness to eat, sensory perceptions and hedonic impressions of foods. Sliced apples and red bell peppers were presented under five different colors of light: white, yellow, green, blue and red, respectively. Participants were asked to observe the presented food under these colored lights, to rate their willingness to eat and liking of food appearance. After tasting, participants were asked to rate intensities of flavor and crispness and rate overall impression of the food. When the food samples were presented under white or yellow light rather than blue light, participants not only wanted to eat more, but also liked the foods more. Participants were especially more willing to eat apples under yellow light than under white light commonly experienced in daily life. Flavor intensity of apples was found to be lower under blue light than under yellow, white or red light; this trend was not observed in flavor intensity of bell peppers. Crispness intensities were not different among the five light‐color conditions. In conclusion, our findings support and extend the notion that light colors modulate consumers’ willingness to eat and their hedonic impressions of foods, especially apples and bell peppers.Practical ApplicationsAs multicolored light‐emitting diode bulbs have become popular, foods and drinks are often displayed under colored light in restaurants and retail stores. The results of this study will provide sensory scientists and food‐service professionals with valuable insights as to how their consumers will most likely behave under colored lights in a given dining establishment. In addition, based on findings that participants’ appetites were significantly higher for apples under yellow light than under white light, yellow light might be used as a tool for encouraging people to consume more apples in everyday life.

RESEARCH OF LEDS AS PHOTOSENSORS

In devices for measuring photovision applied sensors on the basis of photoresistors, photodiodes, vacuum and gas-filled photocells. These photosensors have to add filters and system filters. On the experimental data found that as of photosensors, you can use the LEDs. In laboratory tests, the LEDs of different colors of light react to individual optical radiation. LEDs are not sensitive to radiation with a wavelength longer than at which they emit light. Established that the maximum sensitivity of all LEDs a bit is shifted into the region of shorter wavelength than which the led emits. On the basis of led sensors can make the light meter, RGB-sensors, photosynthesis active radiation and measuring the near UV radiation. With the function of relative spectral luminous efficacy of monochromatic radiation for night vision coincides sensitivity of yellow led with a wavelength of 590 nm. With the function of relative spectral luminous efficacy of monochromatic radiation for daylight vision matches the sensitivity of red LEDs with a wavelength of 625 and 628 nm. To create RGB sensors need LEDs with operating wavelengths 660, 625 and 525 nm. There is no need to use corrective filters.

Hyperproduction of phycobiliproteins by the cyanobacterium Anabaena fertilissima PUPCCC 410.5 under optimized culture conditions

This study was targeted to find new sources of phycobiliproteins (PBP) as these are important as natural colours, antioxidants and fluorescent markers. Here we report Anabaena fertilissima PUPCCC 410.5 as a good producer of PBP. Control cultures of the cyanobacterium produced 383μg PBP mg−1 dry biomass on day 8. The pH of the medium, supplementation of nitrogen source, sugar and illumination of cultures with different colours of light were optimized for PBP production. Optimized individual parameters were: pH of the medium 7.5; supplementation of 2mmol nitrite L−1 or 0.5% sucrose; and illumination of cultures with blue light. Total PBP production under these conditions ranged between 627 and 696μgmg−1 dry biomass, resulting in nearly 1.6 fold increase, with a significant increase in phycocyanin content. Incubation of 2mmol nitrite L−1 supplemented cultures in blue light resulted in nearly 4.5 fold increase in phycoerythrin compared to the control cultures. The PBP/phycocyanin/phycoerythrin production under the optimized conditions by Anabaena fertilissima PUPCCC 410.5 is significantly higher than the PBP production by the other cyanobacterial strains reported in literature. Thus this cyanobacterial strain is a promising candidate for PBP production at commercial level.

Monochromatic light-emitting diode (LED) source in layers hens during the second production cycle

ABSTRACTLight is an important environmental factor for birds, allowing not only their vision, but also influencing their physiological responses, such as behavioral and reproductive activity. The objective of this experiment was to evaluate the impact of different colors of monochromatic light (LED) sources in laying hens production during the second laying cycle. The study was conducted in an experimental laying house during 70 days. A total of 300 laying hens Isa Brown® genetic strain, aged 95 weeks, in the second laying cycle were used in the study. The artificial light sources used were blue, yellow, green, red and white. The light regimen was continuous illumination of 17 h per day (12 h natural and 5 h artificial) in a daily light regimen of 17L:5D (light: dark). The Latin Square design was adopted with five treatments (five colors) divided into five periods, and five boxes, with six replicates of ten birds in each box. The production and egg quality were evaluated. The different colors of light source did not affect production parameters or egg quality (p > 0.05). The monochromatic light source may be considered as an alternative to artificial lighting in laying hens during the second production cycle.

Resonant Nanophotonic Spectrum Splitting for Ultrathin Multijunction Solar Cells.

We present an approach to spectrum splitting for photovoltaics that utilizes the resonant optical properties of nanostructures for simultaneous voltage enhancement and spatial separation of different colors of light. Using metal–insulator–metal resonators commonly used in broadband metamaterial absorbers we show theoretically that output voltages can be enhanced significantly compared to single-junction devices. However, the approach is general and works for any type of resonator with a large absorption cross section. Due to its resonant nature, the spectrum splitting occurs within only a fraction of the wavelength, as opposed to traditional spectrum splitting methods, where many wavelengths are required. Combining nanophotonic spectrum splitting with other nanophotonic approaches to voltage enhancements, such as angle restriction and concentration, may lead to highly efficient but deeply subwavelength photovoltaic devices.

Modelling of fracto-mechanoluminescence damage sensor for structures

The present paper reports the modelling of fracto-mechanoluminescence damage sensor which is useful for real-time and remotely monitoring of both the magnitude and location of damage of the structure without the use of electrodes. In this technique, the intense fracto-mechanoluminescent material of several micron size is mixed in liquid resin and then coated on the surface of structure whereby the occurrence and strength of the damage is given by the intensity of the resulting mechanoluminescence (ML) light. Monitoring of the position of damage is achieved by identifying the colour of ML light emitted as the ML particles coated in different locations emit ML light of different colours. The modelling of fracto-mechanoluminescence damage sensor is based on the fact that the total ML intensity depends on the total area of the newly created surfaces (damage). For a projectile having large contact area such as a cylinder, below the characteristic impact velocity vc, at which the sample is compressed to 1/e of its thickness, both the peak ML intensity Im and the total ML intensity IT increase linearly with the impact velocity; however, above vc, both Im and IT tend to attain saturation value. In the case of impact of a projectile having small contact area such as a ball, below vc, both Im and IT increase quadratically with the impact velocity; however, above vc, both Im and IT tend to attain saturation value. In the case of a projectile having large contact area the total volume of the sample is compressed and only the rate of creation of new surfaces increases with the impact velocity; however, in the case of a projectile having small contact area, in addition to the increase of strain rate with impact velocity, the effective volume compressed by the impact also increases linearly with the impact velocity, and therefore, the rate of creation of new surfaces increases quadratically with the impact velocity. A good agreement is found between the experimental and theoretical results.

ナミヒメハナカメムシ<i>Orius sauteri</i> の波長選好性

Orius sauteri is used as a biological control agent against agricultural pests such as thrips and whiteflies. We investigated the spectral wavelength preference of O. sauteri in a hexagonal arena equipped with six LED lights of different colors: UV (365 nm), violet (405 nm), blue (450 nm), green (525 nm), orange (590 nm), and red (660 nm). Adults were released in the center of the arena and their phototactic behavior toward the LED lights was observed. Approximately 50% of non-mated individuals moved toward the violet light, with no difference between sexes. The spectral preference of males did not change after mating, whereas the preference of females changed dramatically from violet to UV after three days' mating.

Optogenetic analyses of neuronal network function and synaptic transmission in Caenorhabditis elegans

Abstract The transparent nematode Caenorhabditis elegans, with its anatomically well-defined nervous system comprising 302 neurons that regulate quantifiable behaviors, is an ideal model system for the development and ap­plication of optogenetic methods. Optoge­netically modified neurons can be acutely ex­cited or inhibited by light and the effects on a distinct behavior observed. Special light­ing systems allow the manipulation of several nerve cells that act as “nodes” of small neural circuits, with different colors of light, so as to control different optogenetic tools indepen­dently and simultaneously. In addition, ge­netically encoded optical sensors for neuro­nal activity make it possible to draw conclu­sions even when the optogenetic interven­tion causes no obvious behavioral change. The stimulation of quantifiable behaviors permits the analysis of the function of genes necessary in the corresponding neuron for the encoding or amplification of the primary signal. Finally, following optogenetic stimu­lation, the function of chemical synapses and their proteins can also be analyzed by elec­trophysiology or electron microscopy.

Optogenetic analyses of neuronal network function and synaptic transmission in Caenorhabditis elegans

The transparent nematode Caenorhabditis elegans, with its anatomically well-defined nervous system comprising 302 neurons that regulate quantifiable behaviors, is an ideal model system for the development and application of optogenetic methods. Optogenetically modified neurons can be acutely excited or inhibited by light and the effects on a distinct behavior observed. Special lighting systems allow the manipulation of several nerve cells that act as “nodes” of small neural circuits, with different colors of light, so as to control different optogenetic tools independently and simultaneously. In addition, genetically encoded optical sensors for neuronal activity make it possible to draw conclusions even when the optogenetic intervention causes no obvious behavioral change. The stimulation of quantifiable behaviors permits the analysis of the function of genes necessary in the corresponding neuron for the encoding or amplification of the primary signal. Finally, following optogenetic stimulation, the function of chemical synapses and their proteins can also be analyzed by electrophysiology or electron microscopy.

Different colors of light lead to different adaptation and activation as determined by high-density EEG

Light adaptation is crucial for coping with the varying levels of ambient light. Using high-density electroencephalography (EEG), we investigated how adaptation to light of different colors affects brain responsiveness. In a within-subject design, sixteen young participants were adapted first to dim white light and then to blue, green, red, or white bright light (one color per session in a randomized order). Immediately after both dim and bright light adaptation, we presented brief light pulses and recorded event-related potentials (ERPs). We analyzed ERP response strengths and brain topographies and determined the underlying sources using electrical source imaging. Between 150 and 261ms after stimulus onset, the global field power (GFP) was higher after dim than bright light adaptation. This effect was most pronounced with red light and localized in the frontal lobe, the fusiform gyrus, the occipital lobe and the cerebellum. After bright light adaptation, within the first 100ms after light onset, stronger responses were found than after dim light adaptation for all colors except for red light. Differences between conditions were localized in the frontal lobe, the cingulate gyrus, and the cerebellum. These results indicate that very short-term EEG brain responses are influenced by prior light adaptation and the spectral quality of the light stimulus. We show that the early EEG responses are differently affected by adaptation to different colors of light which may contribute to known differences in performance and reaction times in cognitive tests.

Effects of Light Color on Energy Expenditure and Behavior in Broiler Chickens.

This study was conducted in order to investigate whether the presence of light or different colors of light would influence the energy expenditure and behavior of broiler chickens. Eight 8-week-old broiler chickens were adapted to a respiration chamber (Length, 28.5 cm; Height, 38.5 cm; Width, 44.0 cm) for one week prior to the initiation of the experiment. In experiment 1, energy expenditure and behavior of the chickens were analyzed in the presence or absence of light for four days. Chickens were exposed to 6 cycles of 2 h light/2 h dark period per day. In experiment 2, the broiler chickens that had been used in experiment 1 were used to evaluate the effect of 4 different wavelength light-emitting diodes (LEDs) on the energy expenditure and behavior of broiler chickens. The LEDs used in this study had the following wavelength bands; white (control), red (618 to 635 nm), green (515 to 530 nm) and blue (450 to 470 nm). The chickens were randomly exposed to a 2-h LED light in a random and sequential order per day for 3 days. Oxygen consumption and carbon dioxide production of the chickens were recorded using an open-circuit calorimeter system, and energy expenditure was calculated based on the collected data. The behavior of the chickens was analyzed based on following categories i.e., resting, standing, and pecking, and closed-circuit television was used to record these behavioral postures. The analysis of data from experiment 1 showed that the energy expenditure was higher (p<0.001) in chickens under light condition compared with those under dark condition. The chickens spent more time with pecking during a light period, but they frequently exhibited resting during a dark period. Experiment 2 showed that there was no significant difference in terms of energy expenditure and behavior based on the color of light (white, red, green, and blue) to which the chickens were exposed. In conclusion, the energy expenditure and behavior of broiler chickens were found to be strongly affected by the presence of light. On the other hand, there was no discernible difference in their energy expenditure and behavior of broiler chickens exposed to the different LED lights.

Effects of different colors of light on melatonin suppression and expression analysis of Aanat1 and melanopsin in the eye of a tropical damselfish

Ocular melatonin production exhibits a daily rhythm with a decrease during photophase and an increase during scotophase (nocturnal pattern) in teleost fish due to day–night changes in the activity of the rate-limiting melatonin synthesizing enzyme arylalkylamine N-acetyltransferase (AANAT). Acute light exposure during scotophase suppresses AANAT activity and melatonin production in the eyes, suggesting that external light signals are a principal regulator of ocular melatonin synthesis. To better understand the photic regulation of ocular melatonin synthesis in teleost fish, this study sought to characterize the effect of light on ocular melatonin synthesis in the sapphire devil Chrysiptera cyanea, which shows a nocturnal pattern and light-induced inhibition of ocular melatonin production during scotophase. Exposure to three different wavelengths of light (half-peak bandwidth=435–475nm with a peak of 455nm, 495–565nm with a peak of 530nm, and 607–647nm with a peak of 627nm for the blue, green, and red LEDs) for 2h during scotophase resulted in the blue wavelength significantly decreasing ocular melatonin content within 30min after light exposure. This result clearly indicates that the effective range of visible light on ocular melatonin suppression is distributed within the wavelengths of blue light and that a blue light-sensitive opsin is involved in ocular melatonin suppression in the fish. A PCR-based cloning method revealed the expression of melanopsin, a putative blue light-sensitive nonvisual opsin, in the eyes. Furthermore, in situ hybridization using the sapphire devil Aanat1 and melanopsin RNA probes showed mRNA expressions of both genes in the inner nuclear and ganglion cell layer of the fish retina. These results suggest that melanopsin is a possible candidate photoreceptor involved in ocular melatonin suppression by an external light signal in the sapphire devil.

A Novel Double Glowworm Swarm Co-Evolution Optimization Algorithm based L�vy Flights

In this paper, a novel double glowworm swarm co-evolution optimization algorithm based Lflights is presented. According to the different colors of light emitted by glowworm swarm, a certain amount of glowworm swarm was divided into two groups. L´ evy flights with higher randomness were introduced into one group. Then the two groups of glowworm swarm seek the optimal solution simultaneously and co-evolution for achieving the global optimization. The numerical simulation results show that double glowworm swarm co-evolution optimization algorithm based Lflights has greatly improved than the basic algorithm in terms of overall and convergence.

The growth and flowering of Hyacinthus orientalis L. Forced in pots under fluorescent light of different colours

Three hyacinth cultivars were forced under fluorescent lamps which emitted white, blue, green, yellow and red light. The plants started flowering in the first decade of February. The forcing period for two cultivars, ‘Anna Marie’ and ‘Blue Star’, was shortest under lamps emitting red light. The cultivar ‘White Pearl’ flowered equally early under lamps emitting red, white and blue light. The impact of light colour (wavelength) on the leaf greenness index (SPAD) was demonstrated. The photosynthetic activity of leaves was dependent on the cultivar. It was related both to the net rate of photosynthesis and the photosynthetic efficiency. Specific leaf area (SLA) also depended on the cultivar. The level of SLA was related to the rate of photosynthesis and its efficiency. SLA was highest in all cultivars under green and yellow colour light. The chlorophyll content in the fresh and dry weight of leaves was highest under yellow light lamps.

LEDs light spectrum effect on the success of fragmentation and growth of the leather coral Sarcophyton spp.

LEDs light spectrum effect on the success of fragmentation and growth of the leather coral Sarcophyton spp.

Interactive emotional lighting system using physiological signals

This paper proposes an emotionally interactive lighting system to support affective experiences while enjoying video content. The emotional lighting system is controlled by changes in an individual?s emotional state. The newly designed system consists of an emotion recognition system that uses three different physiological signals (photoplethysmography, skin temperature, and galvanic skin response), an emotion lighting control system, and an emotion ambient lighting system. The physiological responses of nineteen subjects are evaluated in terms of emotional arousal and relaxation states with two different colors of light. The physiological signals are analyzed in both the time and frequency domain, and test results show that the peak-to-peak interval value and ratio of high to very-low frequencies of the photoplethysmography signals decreases significantly following a red light stimulus when arousing video content is played, whereas the same factors exhibit a significant increase after a blue light stimulus while relaxing video content is watched. These results show that red and blue light is an effective intensifier of emotional arousal and relaxation experiences during displays of arousing and relaxing video content, respectively.

A facile approach to synthesize SiO2 · Re2O3 (Re = Y, Eu, La, Sm, Tb, Pr) hollow sphere and its application in drug release.

Multifunctional SiO2 · Re2O3 (Re = Y, Eu, La, Sm, Tb, Pr) hollow spheres (HSs) have been fabricated using an acidic Re3+ ion solution. Under ultraviolet radiation, functional HSs emit different colors of light according to the different rare-earth ions embedded into the shell of SiO2 hollow spheres. The as-prepared hollow capsules were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, Brunauer-Emmett-Teller method, scanning electron microscopy, and energy-dispersive spectrometry. Drug loading and release experiments have been carried out using SiO2 · Eu2O3 HSs that acted as drug carriers. The results demonstrate that the multifunctional HSs exhibit a high storage capacity and the ability of retaining drug stability and activity, which indicates that the as-synthesized fluorescent hollow capsules are a potential candidate as drug delivery materials.