Effect Of Light Wavelength Research Articles

Melatonin restores hepatic lipid metabolic homeostasis disrupted by blue light at night in high-fat diet-fed mice.

Artificial light at night (ALAN) is an emerging environmental pollutant that threatens public health. Recently, ALAN has been identified as a risk factor for obesity; however, the role of ALAN and its light wavelength in hepatic lipid metabolic homeostasis remains undetermined. We showed that chronic dim (~5 lx) ALAN (dLAN) exposure significantly promoted hepatic lipid accumulation in obese or diabetic mice, with the most severe effect of blue light and little effect of green or red light. These metabolic phenotypes were attributed to blue rather than green or red dLAN interfering with hepatic lipid metabolism, especially lipogenesis and lipolysis. Further studies found that blue dLAN disrupted hepatic lipogenesis and lipolysis processes by inhibiting hepatic REV-ERBs. Mechanistically, feeding behavior mediated the regulation of dLAN on hepatic REV-ERBs. In addition, different effects of light wavelengths at night on liver REV-ERBs depended on the activation of the corticosterone (CORT)/glucocorticoid receptor (GR) axis. Blue dLAN could activate the CORT/GR axis significantly while other wavelengths could not. Notably, we demonstrated that exogenous melatonin could effectively inhibit hepatic lipid accumulation and restore the hepatic GR/REV-ERBs axis disrupted by blue dLAN. These findings demonstrate that dLAN promotes hepatic lipid accumulation in mice via a short-wavelength-dependent manner, and exogenous melatonin is a potential therapeutic approach. This study strengthens the relationship between ALAN and hepatic lipid metabolism and provides insights into directing ambient light.

Responses of microorganisms to different wavelengths of light radiation during green waste composting

Light radiation can degrade recalcitrant materials like lignocelluloses in litter and serve as a physical condition to accelerate green waste (GW) decomposition, but few studies have considered the microbial effects of light wavelength on GW composting. This study innovatively investigated the effects of different wavelengths of light radiation, including full-spectrum, no blue light, no UV, no UV-A, no UV-B, and dark conditions, on accelerating the GW composting process. Especially, the study explored the dynamic changes in the degradation of lignocelluloses and evaluated the responses of microorganisms throughout the composting process under different light radiation wavelengths. No blue light (where radiation between 400 and 500 nm was blocked by the film) yielded the highest-quality compost within 40 days. In comparison to the dark (control), no blue light exhibited an elevated composting temperature (56.7 °C), an extended thermophilic phase (6 days), and increased degradation rates of lignin, cellulose, and hemicellulose by 13 %, 15 %, and 12 %, respectively. This study revealed that during the composting mesophilic phase, bacterial diversity performed best under no blue light, while fungal diversity excelled under full-spectrum. In the thermophilic phase, microbial diversity exhibited optimal performance under full-spectrum. During the cooling phase, bacterial diversity was highest under no blue light, and fungal diversity excelled under no UV-A. During the mesophilic and cooling phases, the bacterial ACE index for no blue light exceeded that of the other light radiation wavelengths, with values of 418 and 494, respectively. Under no blue light, the Shannon index of microorganisms remained within the range of 2.0–4.8, demonstrating superior performance. Meanwhile, the relative abundances of lignin-degrading microorganisms (Flavobacterium, Acaulium, and Acremoniu) under no blue light has increased, demonstrating improved microbial community structures. Therefore, no blue light radiation offered a novel approach to expedite GW composting.

Blue Light Attracts More Spodoptera frugiperda Moths and Promotes Their Flight Speed.

Light traps are a useful method for monitoring and controlling the important migratory pest, the fall armyworm, Spodoptera frugiperda. Studies have shown that S. frugiperda is sensitive to blue, green, or ultraviolet (UV) light, but the conclusions are inconsistent. Furthermore, conventional black light traps are less effective for trapping S. frugiperda. To improve the trapping efficiency of this pest, it is crucial to determine the specific wavelength to which S. frugiperda is sensitive and measure its flight capability under that wavelength. This study investigated the effects of light wavelength on the phototaxis and flight performance of S. frugiperda. The results showed that blue light was the most sensitive wavelength among the three different LED lights and was unaffected by gender. The flight capability of S. frugiperda varied significantly in different light conditions, especially for flight speed. The fastest flight speed was observed in blue light, whereas the slowest was observed in UV light compared to dark conditions. During a 12 h flight period, speed declined more rapidly in blue light and more slowly in UV, whereas speed remained stable in dark conditions. Meanwhile, the proportion of fast-flying individuals was highest under blue light, which was significantly higher than under UV light. Therefore, the use of light traps equipped with blue LED lights can improve the trapping efficiency of S. frugiperda. These results also provide insights for further research on the effects of light pollution on migratory insects.

Effect of light wavelengths on algal-bacterial symbiotic particles (ABSP): Nitrogen removal, physicochemical properties, community structure

The accumulation of nitrogenous waste, such as ammonia, and its biological nitrification products, namely nitrite and nitrate, poses one of the primary challenges in the water treatment process for Recirculating Aquaculture Systems (RAS). This study proposed the incorporation of light and algal-bacterial symbiotic particles (ABSP)into RAS as a viable solution to address these challenges. The findings indicated that ABSP achieved the RAS water quality standards (ammonia nitrogen <0.5 mg/L, nitrite nitrogen <0.1 mg/L) by the 14th day of operation, while red light achieved and maintained these standards from as early as the 9th day. Further analysis of chemical stoichiometry and functional genes revealed that microalgae (32.7%, 15.6%, 0%) and bacteria (47.7%, 55.8%, 48.4%) were responsible for the assimilation and removal of most organic and nutrient substances under red light, white light, and dark conditions, respectively. Additionally, it was observed that the presence of algae and bacteria in ABSP was significantly influenced by the wavelength of light. Under red light, an optimal distribution of functional species for both microalgae (Characium, Microcoleus, and Uronema) and bacteria (Nakamurella and Micropruina) was achieved, which is crucial for the self-sustaining synergistic reaction and stability of ABSP. This study may offer a promising engineering alternative with enormous potential to achieve energy-efficient and environmentally sustainable RAS water treatment.

Deciphering the Effect of Light Wavelengths in Monilinia spp. DHN-Melanin Production and Their Interplay with ROS Metabolism in M. fructicola.

Pathogenic fungi are influenced by many biotic and abiotic factors. Among them, light is a source of information for fungi and also a stress factor that triggers multiple biological responses, including the activation of secondary metabolites, such as the production of melanin pigments. In this study, we analyzed the melanin-like production in in vitro conditions, as well as the expression of all biosynthetic and regulatory genes of the DHN-melanin pathway in the three main Monilinia species upon exposure to light conditions (white, black, blue, red, and far-red wavelengths). On the other hand, we analyzed, for the first time, the metabolism related to ROS in M. fructicola, through the production of hydrogen peroxide (H2O2) and the expression of stress-related genes under different light conditions. In general, the results indicated a clear importance of black light on melanin production and expression in M. laxa and M. fructicola, but not in M. fructigena. Regarding ROS-related metabolism in M. fructicola, blue light highlighted by inhibiting the expression of many antioxidant genes. Overall, it represents a global description of the effect of light on the regulation of two important secondary mechanisms, essential for the adaptation of the fungus to the environment and its survival.

A Novel LED Light Radiation Approach Enhances Growth in Green and Albino Tea Varieties.

Light, as an energy source, has been proven to strongly affect photosynthesis and, thus, can regulate the yield and quality of tea leaves (Camellia sinensis L.). However, few comprehensive studies have investigated the synergistic effects of light wavelengths on tea growth and development in green and albino varieties. Thus, the objective of this study was to investigate different ratios of red, blue and yellow light and their effects on tea plants' growth and quality. In this study, Zhongcha108 (green variety) and Zhongbai4 (albino variety) were exposed to lights of different wavelengths for a photoperiod of 5 months under the following seven treatments: white light simulated from the solar spectrum, which served as the control, and L1 (red 75%, blue 15% and yellow 10%), L2 (red 60%, blue 30% and yellow 10%), L3 (red 45%, far-red light 15%, blue 30% and yellow 10%), L4 (red 55%, blue 25% and yellow 20%), L5 (red 45%, blue 45% and yellow 10%) and L6 (red 30%, blue 60% and yellow 10%), respectively. We examined how different ratios of red light, blue light and yellow light affected tea growth by investigating the photosynthesis response curve, chlorophyll content, leaf structure, growth parameters and quality. Our results showed that far-red light interacted with red, blue and yellow light (L3 treatments) and significantly promoted leaf photosynthesis by 48.51% in the green variety, Zhongcha108, compared with the control treatments, and the length of the new shoots, number of new leaves, internode length, new leaf area, new shoots biomass and leaf thickness increased by 70.43%, 32.64%, 25.97%, 15.61%, 76.39% and 13.30%, respectively. Additionally, the polyphenol in the green variety, Zhongcha108, was significantly increased by 15.6% compared to that of the plants subjected to the control treatment. In addition, for the albino variety Zhongbai4, the highest ratio of red light (L1 treatment) remarkably enhanced leaf photosynthesis by 50.48% compared with the plants under the control treatment, resulting in the greatest new shoot length, number of new leaves, internode length, new leaf area, new shoot biomass, leaf thickness and polyphenol in the albino variety, Zhongbai4, compared to those of the control treatments, which increased by 50.48%, 26.11%, 69.29%, 31.61%, 42.86% and 10.09%, respectively. Our study provided these new light modes to serve as a new agricultural method for the production of green and albino varieties.

Removal and mineralization of toluene under VUV/UV lamp irradiation in humid air: Effect of light wavelength, O2 and H2O

VUV/UV photodegradation is a promising method that utilizes energetic photons and reactive oxygen species (ROS) generated via the photo-dissociation of H2O and O2 to degrade VOCs. In the paper, we investigated the efficiency of removal and mineralization in humid air and the effects of key factors. Toluene of 4–20 ppm can be almost completely removed in 60 s and mineralization efficiency is above 55% at 25 min. 185 nm ultraviolet light plays a key role in the rapid removal and mineralization of toluene. Appropriate amount of O2 and H2O promote the removal of toluene due to the generation of ROS. Based on the intermediates and degradation pathway analysis, it is found that in the presence of O2, degradation pathways of toluene are more abundant and fewer linear-chain aldehydes are produced, thus resulting in higher mineralization efficiency. This work highlights the importance of practical application of VUV/UV photodegradation in humid air.

Carotenogenesis and carotenoid esterification in biofilms of the microalga Coelastrella rubescens KGU-Y002 in the aerial phase

Water supply, light intensity, and the light spectrum are important parameters that affect the growth of microalgae, but their influence on cultivation of carotenoid-rich microalgae in aerial conditions has not been thoroughly studied. In this work, the effects of water supply, light intensity, and the applied light spectrum on aerial-phase biofilms of the aerial microalga Coelastrella rubescens KGU-Y002 were investigated. First, the appropriate supply of water was investigated. In the presence of sufficient water, the microalga (1 g dry cell weight) consumed approximately 50 g of water in 7 days of culture. It was necessary to supply 8.8 mL g−1 d−1 of water to the biofilm to maintain biological activity. In aerial conditions, the microalga was able to fix carbon dioxide for biosynthesis of carotenoids and fatty acids. Next, the effect of light intensity was examined. The total and ester-type carotenoid contents were highest on illumination at 100 μmol photons m−2 s−1; after 7 days, they were 2.4- and 2.1-times those at the start of culture, respectively. The effect of light wavelength from light emitting diodes (LEDs) on carotenoid accumulation and esterification in the microalga was investigated. When the biofilm was irradiated using red LEDs, the contents of total carotenoids and carotenoid esters were increased approximately three and nine times, respectively, after 7 days compared with those at the start of the culture. Because fatty acids were synthesized, ester-type carotenoids were efficiently synthesized. Blue light promoted cell division and increased the total fatty acid content but decreased the total carotenoid content compared with red or green light. For carotenoid production from the microalga C. rubescens in aerial phase conditions, the cells under blue light can be proliferated, and then switched to red-light illumination to promote carotenoid biosynthesis.

Histological, antioxidant, apoptotic and transcriptomic responses under cold stress and the mitigation of blue wavelength light of zebrafish eyes

As global climate changes, severely temperature variations have significant impacts on survival and development of fish. While the potential effects of light wavelength on cold shock and associated mechanisms remain largely unknown in fish. Here, zebrafish (Danio rerio) were pre-exposed to white LEDs (Light emitting diodes) at an irradiance of 0.9 W/m2 and blue LEDs (LDB, peak at 450 nm, 0.9 W/m2) for 2 weeks, and then exposed to 26 ℃ or 11 ℃ for 48 h, respectively. Cold shock led to low survival rate. Cold shock altered retinal structure, increased the number of apoptotic cells and Caspase-3 activity, inhibited superoxide dismutase (SOD) and catalase (CAT) activities, up-regulated mRNA expression of nrf2 (NF-E2-related factor 2), p53 (Tumor suppressor), casp3 (Caspase-3) and casp9 (Caspase-9), and down-regulated cat (Catalase) expression in fish eyes. These results demonstrated that acute cold exposure induced oxidative stress and apoptosis in zebrafish eyes, which may lead to mortality. However, cold shock in combination with LDB apparently mitigated these negative effects, which might be involved in the up-regulation of antioxidant response and down-regulation of apoptotic responses at transcriptional and translational levels. Furthermore, cold shock also caused dysregulation of genome-wide gene expression involved in circadian rhythm, phototransduction and il-17 signaling pathway, indicating that cold shock disturbed phototransduction cascade and circadian rhythm signals and caused inflammatory responses. Ten key genes involved in circadian rhythm, phototransduction, cell cycle arrest, RNA processing or inflammatory responses were identified, including muc5d (Mucin 5d), rnps1 (RNA-binding protein with serine-rich domain 1), si:dkey-243i1.1, opn1mw1 (Medium-wave-sensitive opsin 3), gadd45ba (Growth arrest and DNA damage-inducible protein), cebpd (CCAAT/enhancer binding protein delta), btg2 (Anti-proliferative cofactor), si:dkey-242g16.2, nr1d1 (Nuclear receptor subfamily 1 group D member 1) and zgc:122979, which may play an important role in the protection of LDB against cold shock. Finally, our study suggested the relationship between spectrum and cold stress and demonstrated LDB could protect fish against the negative effect of cold stress in the eyes.

Visible light-driven photothermal Au/Ag/TiO2 trihybrid plasmonic nanomaterial for synthetic fuel production

In the present article, a new numerical investigation is conducted to quantify the fluidic flow-photothermal performance of a trihybrid nano-catalyst for biomethane reforming inside a 1 μm micro-reactor on gold-silver nanoparticles coated on titanium oxide (TiO2). The model generates a two-way coupling between heat, mass, fluid flow and electromagnetic profiles to simulate the plasmonic effect for the plasmonic photocatalyst in a micro-boundary layer adjacent to the catalyst. The effect of light wavelength on operating parameters and system performance was investigated and discussed. This included chemical conversion, the lower heating value of the syngas, mole fractions of species in the gaseous product, and the spatiotemporal velocity profiles. It was found that light absorptance by the nanoparticles is highest when visible light wavelength within 570 nm < λ < 590 nm is used to stimulate the plasmonic nanostructure. Also, the chemical conversion reached 81% at an exposure time of 1 μs of visible light. At λ = 570 nm, the produced syngas had a lower heating value of 311 kJ/mol and syngas quality of 0.16, which is suitable for ethanol production. Also, a maximum temperature elevation of 998 K was achieved which is above the minimum temperature required for reforming methane (823 K). The spatiotemporal velocity and chemical conversion profiles across the micro-reactor showed that at exposure times > 5 μs, both profiles become fully developed resulting in the suppression of chemical conversion.

Wavelength-dependent photoactivity of ZnxCd1−xS and ZnCo2O4/ZnxCd1−xS for H2 and H2O2 production

Zinc cadmium sulfide (ZnxCd1−xS) is a good photocatalyst for hydrogen evolution reaction (HER), but an optimum x (xm) at which a maximum HER rate is reached varies from one report to another. In this work, we examine the effect of light wavelength, not only for the HER to H2 in the presence of Na2S and Na2SO3, but also for oxygen reduction reaction (ORR) without addition of any sacrifices. For the HER under a 365 and 420 nm LED lamp, the xm were 0.9 and 0.7, respectively. For the HER under a 330 and 395–515 nm cut-off xenon lamp, the xm were 0.7 and 0.5, respectively. For the ORR under a 420 nm cut-off halogen lamp, a maximum production of H2O2 was observed at x = 0.3. Furthermore, after 4% ZnCo2O4 loading, ZnxCd1−xS had an increased activity and stability, either for the HER or for the ORR. Through a (photo)electrochemical measurement, it is proposed that the photocatalytic activity of ZnxCd1−xS is determined by its light absorptivity and electron reactivity. The improved performance of n-type ZnxCd1−xS by p-type ZnCo2O4 is due to formation of a p-n junction, promoting the HER (ORR) on ZnxCd1−xS, and the sulfide (water) oxidation on ZnCo2O4. This work highlights that ZnxCd1-xS is a promising photocatalyst for H2 and H2O2 production, respectively.

Potential of plasmonic microreactor for Photothermal hydrogen-enriched fuel production from biomethane

In the present article, a series of coupled computational physics - fluid dynamics models were developed aiming at assessing the feasibility of photothermal synthetic fuel production from biogas (biomethane) and steam blends using plasmonic nanostructure Ag/TiO2 substrate (each, 0.1 μm in thickness) inside a thermal, momentum and mass transport boundary layer in a microreactor. A chain of partial and complete biogas reforming and water-gas shift reactions were modelled as the dominant chemical reactions responsible for synthetic fuel production from biomethane. Using equilibrium analysis, plausible thermodynamic operating conditions were identified and applied to the computational models. The effect of light wavelength (λ) on the reaction rate, chemical conversion extent, syngas quality, exergy partitioned in synthetic fuel, and composition of gas products were investigated. The results showed that the performance of the microreactor is wavelength-dependent. It was found that the highest production rate for the synthetic fuel was achieved at 580 nm < λ < 620 nm. Within the same wavelength range, the chemical conversion of biomethane to synthetic fuel reached 85% at steam to methane ratio of 3 and the synthetic fuel quality was >2.05, which is suitable for a Fischer-Tropsch process. It was also identified that the syngas quality of the synthetic fuel can be regulated by adjusting the wavelength of the light. The exposure time was also identified to be a critical parameter affecting the performance of the microreactor. For an exposure duration of up to 10 ns, high quality of synthetic fuel >2.05 can be achieved within the optimum wavelength range of 580 nm < λ < 620 nm.

Bunch of Grape-Like Shape PANI/Ag2O/Ag Nanocomposite Photocatalyst for Hydrogen Generation from Wastewater

Polyaniline (PANI) and PANI/Ag2O/Ag composites I and II were prepared under different AgNO3 oxidant concentrations using the oxidative photopolymerization method. The chemical structure and optical, electrical, and morphological properties were determined for the prepared nanocomposite. The PANI/Ag2O/Ag composite II has the optimum optical properties, in which the bandgaps of PANI, composite I, and composite II are 3.02, 1.71, and 1.68 eV, respectively, with the morphology of a bunch of grape-like shapes with average particles sizes of 25 nm. Under the optimum optical properties, glass/PANI/Ag2O/Ag composite II electrode is used for hydrogen generation from sewage water. The measurements are carried out from a three-electrode cell under a xenon lamp. The effects of light wavelengths and temperature on the produced current density ([Formula: see text]) are mentioned. Under the applied voltage (at 30°C), the current density values ([Formula: see text]) increase from 0.003 to 0.012 mA.cm-2 in dark and light, respectively. While increasing the temperature, [Formula: see text] values increase to 0.032 mAcm-2 at 60°C. The thermodynamic parameters are calculated, in which the activation energy ([Formula: see text]), enthalpy ([Formula: see text]), and entropy ([Formula: see text]) values are 27.1 kJ·mol-1, 24.5 J mol-1, and 140.5 J K-1 mol-1, respectively. Finally, a simple mechanism for the produced hydrogen generation rate is mentioned. The prepared electrode is a very cheap (1$ for [Formula: see text]) electrode.

Self-powered ultraviolet photodetector based on an n-ZnO:Ga microwire/p-Si heterojunction with the performance enhanced by a pyro-phototronic effect.

In the present study, a heterojunction made of an individual ZnO microwire via Ga incorporation (ZnO:Ga MW) with a p-Si substrate was constructed to develop a self-powered ultraviolet photodetector. When operated under an illumination of 370 nm light with a power density of ∼ 0.5 mW/cm2, the device exhibited an excellent responsivity of 0.185 A/W, a large detectivity of 1.75×1012 Jones, and excellent stability and repeatability. The device also exhibited a high on/off photocurrent ratio up to 103, and a short rising and falling time of 499/412 μs. By integrating the pyro-phototronic effect, the maximum responsivity and detectivity increased significantly to 0.25 A/W and 2.30×1012 Jones, respectively. The response/recovery time was drastically reduced to 79/132 μs without an external power source. In addition, the effects of light wavelength, power density, and bias voltage on the photocurrent response mediated by the pyro-phototronic effect were systematically characterized and discussed. Our work not only provides an easy yet efficient procedure for constructing a self-powered ultraviolet photodetector but also broadens the application prospects for developing individual wire optoelectronic devices based on the photovoltaic-pyro-phototronic effect.

Effect of light wavelength on soybean growth and development in a context of speed breeding

AbstractSoybean [Glycine max (L.) Merr.] breeding involves crossing and inbreeding for multiple generations to develop genetically stable lines. The long generation times cause early generations to be the major bottleneck in soybean breeding. Here we tested the effect of red and blue light (RB) and full‐spectrum white light (FS), coupled with 12‐h light (29 °C) vs. 12‐h darkness (27 °C) photothermal conditions, on the growth and development of soybean lines and breeding materials of diverse maturity groups (MGs) in a context of speed breeding. We observed that RB light vs. FS light reduced plant height but did not affect vegetative biomass, pods and seeds per plants, nor the ability to meet a minimum of one seed per plant. Overall, the RB treatment reduced the interval planting to physiological maturity by 1.5 d vs. the FS treatment. The period between planting and harvest of mid‐ and late‐maturity soybean ranged from 63 to 81 d, vs. ∼120 d observed in field conditions. Also, days after planting (DAP) to R7 was dependent on soybean MG. The use of RB light, coupled with photothermal conditions herein reported, would allow to advance up to five generations of U.S.‐adapted soybean under a controlled environment instead of the one to three generations currently possible. This methodology is simple and easily scalable, for it maintains stable growing conditions throughout the crop cycle and it allows for simultaneous planting and harvesting within the same growth room. This could have a significant impact in genetic gain of U.S. soybean breeding programs.

Management of flying insects on expressways through an academic-industrial collaboration: evaluation of the effect of light wavelengths and meteorological factors on insect attraction

Insect outbreaks often occur in the absence of natural enemies and in the presence of excess suitable host materials. Outbreaks of gypsy moths are especially problematic in remote areas located in high-latitude regions in Japan because the majority of adults emerge during the short summer season and initiate synchronous mass flight toward artificial lights. The aggregation of moths in public facilities not only is an annoyance to visitors but also permits the establishment of new populations the following year. The aim of this study was to establish a method to reduce the numbers of large moths that are attracted to lights in the rest areas of expressways in Hokkaido based on the results of research on their behavioral ecology and physiology. First, we conducted extensive insect surveys using light traps that emit light at different wavelengths; the traps were set along the expressways in the summers of 2014–2018. The insects attracted to the light were roughly classified into those showing a preference for broadband light wavelengths (from UV-A to green) and short light wavelengths (from UV-A to blue). The former included aquatic insects and winged ants, and the latter included moths and beetles. Next, we analyzed correlations between moth emergence and daily meteorological data. When gypsy moths were abundant during an outbreak, the daily catch of gypsy moths was positively correlated with the highest ambient temperature on the catch day but not with the visibility range, wind speed, or moon phase. In contrast, the daily catch of oak silkmoths did not correlate with any of these parameters. Our results provide guidance for the management of forest insects inhabiting cool-temperate to subarctic regions based on light wavelengths with reference to weather variables.

U-turn time and velocity dependence on the wavelength of light: multicellular magnetotactic prokaryotes of different sizes behave differently.

'Candidatus Magnetoglobus multicellularis' is a multicellular magnetotactic prokaryote found in the Araruama lagoon in Rio de Janeiro, Brazil. This microorganism shows a photokinesis that depends on the incident light wavelength, but that dependence can be canceled by the presence of radio-frequency (RF) electromagnetic fields. The present manuscript has as its aim to study the effect of light wavelength and RF fields on the U-turn time of 'Candidatus Magnetoglobus multicellularis', a behavior more related to magnetotaxis. As the experiments were performed during the night, the microorganisms were greater in size than normal, indicating that they were in the process of division. Our results show that when normal in size, the microorganism's U-turn time is modified by the light wavelength (lower for blue light than for green and red light), but RF fields do not affect that U-turn time dependence on the light wavelength. For the microorganism in the process of division, we describe for the first time how the photokinesis and U-turn time dependence on the light wavelength disappear. It is proposed that methyl-accepting chemotaxis proteins are involved in that light wavelength dependence for the U-turn time, but still more studies are necessary to understand how RF fields cancel the photokinesis light wavelength dependence, but do not affect the dependence of the U-turn time.

Enhancing the degradation of carbamazepine by UVA-LED/WO3 process with peroxydisulfate: Effects of light wavelength and water matrix

In this study, peroxydisulfate (PDS) was used as electron acceptor to improve the photocatalytic activity of WO3. The results indicated that the degradation of carbamazepine by UVA-LED/WO3/PDS process followed pseudo-first order and PDS addition significantly enhanced the degradation rate by inhibiting the recombination of electrons and holes. The observed pseudo-first order rate constant (kobs) was in linear relationship with the dosage of WO3, while inversely proportional to the initial concentration of CBZ. PDS decreased the kobs slightly when its concentration exceeded 0.5 mM. The 365 nm UVA-LED performed much better than 385 nm or 405 nm even though its energy efficiency was the lowest. Based on the steady-state kinetic model, sulfate radical was the dominant radical. The effects of water matrix were complex: bicarbonate ion and humic acid showed strong inhibitory effect; increasing the pH above 7 led to significant drop in CBZ removal; sulfate ion slightly decreased the kobs while 5 mM chloride ion more than doubled the kobs. The interactions between anions and WO3 surface were theoretically analysed to explain the effects of anions. The electrical energy per order values suggest that UVA-LED/WO3/PDS process is suitable for water with low organic carbon.

Modeling the effects of light wavelength on the growth of Nostoc ellipsosporum

Mathematical models provide information about population dynamics under different conditions. In the study, four models were evaluated and employed to describe the growth kinetics of Nostoc ellipsosporum with different light wavelengths: Baranyi-Roberts, Modified Gompertz, Modified Logistic, and Richards. N. ellipsosporum was grown in BG-11 liquid medium for 9 days, using 12 hours of photoperiod and the following treatments: white light (400-800 nm), red light (650-800 nm), yellow light (550-580 nm) and blue light (460-480 nm). Each experiment was performed in triplicate. The optical density (OD) was measured on days 1, 3, 5, 7 and 9, using a spectrophotometer at 650 nm. The maximum cell growth was obtained under white light (OD650 : 0.090 ± 0.008), followed by the yellow light (OD650 :0.057 ± 0.004). Conversely, blue light showed a marked inhibitory effect on the growth of N. ellipsosporum (OD650 : 0.009 ± 0.001). The results revealed that the Baranyi-Roberts model had a better fit with the experimental data from N. ellipsosporum growth in all four treatments. The findings from this modeling study could be used in several biotechnological applications that require the productionof N. ellipsosporum and its bioproducts.

A comprehensive study on the effect of light quality imparted by light-emitting diodes (LEDs) on the physiological and biochemical properties of the microalgal consortia of Chlorella variabilis and Scenedesmus obliquus cultivated in dairy wastewater.

The effect of light wavelengths on the physiological, biochemical and lutein content of the microalgal consortia Chlorella variabilis and Scenedesmus obliquus was evaluated using different light sources. Among different light treatments, cool-white fluorescent light produced the highest biomass of 673 mg L-1 with a specific growth rate of 0.75 day-1 followed by blue (500 mg L-1; 0.73 day-1). The chlorophyll content was enhanced under blue light (10.7 mg L-1) followed by cool fluorescent light (9.3 mg L-1), whereas the lutein productivity was enhanced under cool fluorescent light (7.22 mg g-1). Protein content of the microalgal consortia was enhanced under all light treatments with the highest protein accumulation under cool-white fluorescent light (~56% of dry mass) closely followed by amber light (52% of dry mass), whereas the carbohydrate content was higher under amber light (~35% of dry mass). The results revealed that the consortia could grow well on diluted dairy wastewater thereby reducing the cost of algal production when compared with the use of inorganic media and a two-phase culture process utilizing cool fluorescent and amber light could be employed for maximizing algal biomass and nutrient composition with enhanced lutein production. The study also emphasizes on the economic efficiency of LED lights in terms of biomass produced based on the modest electricity consumed and the importance of using amber light for cultivating microalgae for its nutrient content which has seldom been studied.