Red Light Wavelength Research Articles

Exploring the photosensitizing potential of Nanoliposome Loaded Improved Toluidine Blue O (NLITBO) Against Streptococcus mutans: An in-vitro feasibility study.

Streptococcus mutans is a major contributor to dental caries due to its ability to produce acid and survive in biofilms. Microbial resistance towards common antimicrobial agents like chlorhexidine and triclosan has shifted the research towards antimicrobial Photodynamic therapy (PDT). In this context, Toluidine Blue O (TBO) is being explored for its photosensitizing properties against Streptococcus mutans. There is a huge variation in the effective concentration of TBO among the current studies owing to the differences in source of and delivery system TBO as well as the time, power and energy densities of light. The primary objectives of this study are to encapsulate improved Toluidine Blue O (ITBO) in nanoliposomes (NLITBO), characterize it, and evaluate its antibacterial photosensitizing potential against Streptococcus mutans suspensions in vitro. ITBO was synthesised as per Indian patent (number -543908). NLITBO was prepared using the thin-film hydration method. Dynamic light scattering experiment determined the vesicle size, polydispersity index (PDI), and zeta potential. Surface features were characterized by Scanning and Transmission Electron microscopy. ITBO release from NLITBO was assessed using the extrapolation method. The antibacterial activity of the NLITBO was determined by evaluating the zone of inhibition (ZOI) in the Streptococcus mutans culture and comparing with 2% chlorhexidine gluconate. The minimum inhibitory concentration (MIC) of NLITBO as a photosensitizer with red light (wavelength 650nm, power density 0.1 W/cm2, energy density 9-9.1 J/ cm2, 90seconds time) was evaluated against Streptococcus mutans cells by colorimetric method in 96 well plate. Percentage drug loading, loading efficiency, yield percentage, vesicle size, PDI, Zeta potential of NLTBO was reported as 9.3±0.4%, 84.4±7.6%, 73.5%, 123.52 nm, 0.57, -39.54mV respectively. Clusters of uni-lamellar nanovesicles with smooth non-perforated surfaces were observed in SEM and TEM. The size of the vesicle was within 100 nm. At 24 hours, a cumulative 79.81% of ITBO was released from NLITBO. Mean ZOI and MIC of NLITBO (1 μg /ml) were found to be 0.7±0.2 mm, 0.6μg/ml respectively. We have synthesized and encapsulated improved Toluidine Blue O (ITBO) in nanoliposomes (NLITBO) and thoroughly characterized the formulation. The antibacterial efficacy of NLITBO without light was demonstrated by ZOI which is similar to 2% chlorhexidine gluconate. MIC of NLITBO as a photosensitiser along with the optimal light parameter was also proposed in this study. These findings suggested that NLITBO could serve as an effective alternative to conventional antibacterial treatments in managing Streptococcus mutans rich biofilms. It can have potential pharmaceutical application in oral health care.

Alterations in visible light exposure modulate platelet function and regulate thrombus formation

BackgroundVariations in light exposure are associated with changes in inflammation and coagulation. The impact of light spectra on venous (VT) and arterial thrombosis is largely unexplored. ObjectivesTo investigate the impact of altering light spectrum on platelet function in thrombosis. MethodsWild type (WT) C57BL/6J mice were exposed to ambient (micewhite, 400lux), blue (miceblue, 442nm, 1,400lux), or red light (micered, 617nm, 1,400lux) with 12:12 hour light:dark cycle for 72 hours. After 72 hours of light exposure, platelet aggregation, activation, transcriptomic, and metabolomic changes were measured. The ability of released products of platelet activation to induce thrombosis-generating NET formation was quantified. Subsequent thrombosis was measured using murine models of VT and stroke. To translate our findings to human patients, light filtering cataract patients were evaluated over an 8-year period for rate of VTE with multivariable logistic regression clustered by hospital. ResultsExposure to long wavelength red light resulted in reduced platelet aggregation and activation. RNA-seq analysis demonstrated no significant transcriptomic changes between micered and micewhite. However, there were global metabolomic changes in platelets from micered compared to micewhite. Releasate from activated platelets resulted in reduced NET formation. Micered also had reduced VT weight and brain infarct size following stroke. On subgroup analysis of cataract patients, patients with a history of cancer have lower lifetime risk of VTE after implantation with lenses that filter low wavelength light. ConclusionsLight therapy may be a promising approach to thrombus prophylaxis by specifically targeting the intersection between innate immune function and coagulation.

Assessment of reproductive hormones in prepubertal and postpubertal rats (<i>Rattus norvegicus</i>) on chronic exposure to various spectra of artificial light at night

Exposures to Artificial Light at Night (ALAN) is on the increase with resultant varied physiological impact related to the light spectrum via the non-visual pathway. This study examined the effects of various spectra of ALAN on Testosterone (Te), Progesterone (Pr) and Estradiol (Es) in rats exposed to Blue (BL), Green (GL), Yellow (YL), Red (RL), White (WL) and Darkness (DD) light wave-lengths while Ambient light (CL) served as the control. Dams with their post-natal day 1 pups were housed in cages exposed to various light wavelengths for 12 hours: (6:00pm–6:00am) daily for 126 days. At d63 and d126, five rats per treatments were euthanized; blood serum was collected and the serum hormones: Te, Es and Pr were analysed using ELISA. The results showed that light treatments had significant effect on the level of Te at d63 but not at d126 in male rats. At d63, onset of puberty, Te was significantly highest (p < 0.05) under BL. In females exposed to YL and WL at d126, Te was significant high and Es was significantly low. Estradiol was heightened significantly (p < 0.05) in both sexes exposed to RL. In conclusion, BL seemed to stimulate early sexual development in males, WL and GL enhanced post-pubertal male albino rat reproductive system while RL provided the best reproductive environment for females in the long term. Long periods of exposure to YL seemed to pose risks for male and female reproductive function.

TRANSCRANIAL NEAR-INFRARED THERAPY FOR COGNITIVE PERFORMANCE AND NEUROLOGICAL STATUS ENHANCEMENT

There is a growing interest in non-invasive treatment options in the field of neurotherapy with transcranial near-infrared (tNIR) light demonstrating promising results across a broad spectrum of neurological disorders. This paper explores the therapeutic potential of tNIR and its efficacy in stimulating cellular functions to improve outcomes in neurodegenerative diseases such as dementia, Parkinson’s disease, Alzheimer’s disease as well as traumatic brain injury, stroke recovery, neuroinflammatory conditions, depression, and BDNF stimulation. Through the direct transcranial application of low-level wavelengths of red or near-infrared light, tNIR stimulation activates neural tissue metabolism, modulates brain function, enhances cognitive performance, and alleviates chronic brain inflammation. This study synthesizes current research findings to illustrate the mechanisms underlying tNIR's action, evaluates its potential across various neurotherapeutic applications, and presents an overview of its current therapeutic implementations. Studies demonstrate the tNIR's capacity to penetrate the skull, stimulate neural tissues, enhance mitochondrial function, and increase ATP production. tNIR has been shown to improve cognitive functions and reduce neuroinflammation, offering a novel approach to treating neurodegenerative conditions. tNIR’s application extends to stroke recovery, where it has been shown to reduce infarct zones as well as nerve regeneration through promoting synaptogenesis and BDNF stimulation.

Morpho-physio-biochemical, molecular, and phytoremedial responses of plants to red, blue, and green light: a review.

Light is a basic requirement to drive carbon metabolism in plants and supports life on earth. Spectral quality greatly affects plant morphology, physiology, and metabolism of various biochemical pathways. Among visible light spectrum, red, blue, and green light wavelengths affect several mechanisms to contribute in plant growth and productivity. In addition, supplementation of red, blue, or green light with other wavelengths showed vivid effects on the plant biology. However, response of plants differs in different species and growing conditions. This review article provides a detailed view and interpretation of existing knowledge and clarifies underlying mechanisms that how red, blue, and green light spectra affect plant morpho-physiological, biochemical, and molecular parameters to make a significant contribution towards improved crop production, fruit quality, disease control, phytoremediation potential, and resource use efficiency.

Effects of Light Color on the Growth, Feeding, Digestion, and Antioxidant Enzymes of Tripneustes gratilla (Linnaeus, 1758).

To study the effects of light color on sea urchin (Tripneustes gratilla), blue light (B, λ450nm), yellow light (Y, λ585-590nm), red light (R, λ640nm), green light (G, λ510nm), white light (W, λ400-780nm), and darkness (H) groups were established in a recirculating seawater aquaculture system. Six different LED light color treatment groups with a photoperiod of 12 L:12 D were tested for 30 days to investigate the effects of different light colors on the feeding, growth, and enzyme activities of T. gratilla (142.45 ± 4.36 g). We found that using different LED light colors caused significantly different impacts on the feeding, growth, and enzyme activity of T. gratilla. Notably, the sea urchins in group B exhibited better growth, with a weight gain rate of 39.26%, while those in group R demonstrated poorer growth, with a weight gain rate of only 26%. The feeding status differed significantly (p < 0.05) between groups B and R, with group B consuming the highest daily intake (6.03 ± 1.69 g) and group R consuming the lowest (4.54 ± 1.26 g). Throughout the three phases, there was no significant change in the viability of the α-amylase (p > 0.05). Conversely, the pepsin viability significantly increased (p < 0.05) in group B. The lipase viability consistently remained at the lowest level, with no notable differences between group W and group B. In group R, both the α-amylase and pepsin viabilities remained lower, whereas the lipase viability was noticeably greater in each phase than in group B (p < 0.05). Among the antioxidant enzymes, group R exhibited a trend of initial increase followed by decreases in catalase, superoxide dismutase, and glutathione peroxidase activities, particularly during the third stage (15-30 days), during which a significant decrease in antioxidant enzyme activity was observed (p < 0.05). Taken together, these findings suggest that blue light positively affects the growth, feeding, digestion, and antioxidant capacity of T. gratilla in comparison with those in other light environments, whereas red light had an inhibitory effect. Furthermore, T. gratilla is a benthic organism that lives on shallow sandy sea beds. Thus, as short wavelengths of blue and green light are more widely distributed on the seafloor, and long wavelengths of red light are more severely attenuated on the seafloor, shorter wavelengths of light promote the growth of bait organisms of sea urchins, which provide better habitats for T. gratilla.

Study on the subjective brightness of photonic crystal structural colored wood products

ABSTRACT Photonic crystal structural color is a novel method in the field of colored coating on the surface of wood products. However, the subjective brightness of photonic crystal structural colored wood products under different color temperature light sources has not been studied. In this study, poly(styrene-methyl methacrylate-acrylic acid) latex microspheres with different diameters were used to construct photonic crystal coatings on wood surface. The subjective brightness psychological quantity under different color temperature light sources was obtained. Combined with the optical properties of the coatings, the correlation between the physical optical properties of the photonic crystal coating, the color temperature of the light source and the subjective brightness of the coating was obtained. The photonic crystal coating in the near red visible light wavelength range had higher subjective brightness under low color temperature light source, and coating in the near purple visible light wavelength range had higher subjective brightness under high color temperature light source. The subjective brightness of the photonic crystal coating was very closely related to the light source color temperature and closely related to the reflectivity of the coating. This study expands the research on the optical properties of photonic crystal structure colored wood products.

A Short and Practical Overview on Light-Sensing Proteins, Optogenetics, and Fluorescent Biomolecules inside Biomorphs Used as Optical Sensors

In this contribution, we describe a brief overview of the role of different light-signaling proteins in different biochemical processes (mostly in plants) along the electromagnetic spectrum. We also revise, in terms of perspectives, the applications of all these proteins to optogenetics as a new emerging field of research. In the second part, we present some case studies: First, we used two fluorescent proteins showing an optical response in the green- and red-light wavelengths both isolated from marines’ organisms, which were incorporated as light sensors into the silico-carbonate of Ca, Ba, and Sr (usually called biomorphs). The second case study consisted in incorporating phototropins from a plant (Arabidopsis thaliana) into the synthesis of biomorphs. Finally, the last part analyses the influence of these three proteins on the shape and structure in the synthesis of silico-carbonates of calcium, barium, and strontium as optical sensors, in order to detect the location of these biomolecules inside these self-assembly crystalline materials called biomorphs.

Enhancing the bio-prospective of microalgae by different light systems and photoperiods.

Microalgae are a source of highly valuable bioactive metabolites and a high-potential feedstock for environmentally friendly and sustainable biofuel production. Recent research has shown that microalgae benefit the environment using less water than conventional crops while increasing oxygen production and lowering CO2 emissions. Microalgae are an excellent source of value-added compounds, such as proteins, pigments, lipids, and polysaccharides, as well as a high-potential feedstock for environmentally friendly and sustainable biofuel production. Various factors, such as nutrient concentration, temperature, light, pH, and cultivation method, effect the biomass cultivation and accumulation of high-value-added compounds in microalgae. Among the aforementioned factors, light is a key and essential factor for microalgae growth. Since photoautotrophic microalgae rely on light to absorb energy and transform it into chemical energy, light has a significant impact on algal growth. During micro-algal culture, spectral quality may be tailored to improve biomass composition for use in downstream bio-refineries and boost production. The light regime, which includes changes in intensity and photoperiod, has an impact on the growth and metabolic composition of microalgae. In this review, we investigate the effects of red, blue, and UV light wavelengths, different photoperiod, and different lighting systems on micro-algal growth and their valuable compounds. It also focuses on different micro-algal growth, photosynthesis systems, cultivation methods, and current market shares.

EFFECTIVENESS OF THE PHOTON CAPTURE BEAM TECHNOLOGY AND PHOTODYNAMIC IMPACT ON MALIGNANT HUMAN CELLS ІN A RESTING STATE.

to investigate the structural and morphofunctional changes in test system of malignant (cell line A-549) human cells in a resting state exposed to X-rays in the presence of gadolinium-containing photon capture agent «Dotavist» and optical light (red spectrum) in combination with «Photolon» photosensitizer. Passaged malignant human cell culture technology, X-ray and red light exposure, cytological and statistical methods. X-ray exposure at a dose of 10.0 Gy in the presence of photon capture agent «Dotavist» (at a 100 μg/ml nutrient medium concentration) led to death of 75-83 % of malignant cells in a resting state on the 6-8th day of cultivation. Photodynamic exposure (630 nm wavelength red light) in the presence of «Photolon» photosensitizer (200 μg/ml concentration) resulted in death of 69-73 % of malignant cells, respectively. Combination of the photon-capturing technology and photodynamic exposure resulted in death of 90 % of the malignant cells in a phase of steady-state growth on the 8th day of cultivation. Combination of the photon capture technology (X-ray exposure with gadolinium-containing photoncapture agent «Dotavist» in cytotoxic concentration) and photodynamic exposure in the presence of «Photolon» photosensitizer increased devitalization effectiveness of human non-small cell lung cancer cells (A-549 cell line) being in a steady-state growth phase up to 90 %. Ten percent of cells resistant to the applied technologies retained their proliferative potential, evident as changes in their morphology, genotype and adhesiveness during further cultivation.

Light Quality-Mediated Influence of Morphogenesis in Micropropagated Horticultural Crops: A Comprehensive Overview.

In plants, light quality plays significant roles in photomorphogenesis and photosynthesis. Efficient in vitro plant propagation techniques involve tailoring of various environmental cues and culture media according to the plant species. Plant tissue culture consists of several applications in scientific research, agriculture, biotechnology, and commercial industrial purposes. Utilization of light to enhance the quality of the in vitro raised plants have been evidenced by numerous researchers in plant tissue culture. The advent of light-emitting diode- (LED-) based artificial lighting systems in plant tissue culture for micropropagation has enhanced callus induction, shoot and root organogenesis, and acclimatization of in vitro propagated plants. Plants tend to perceive the light spectra present in the photosynthetically active region (PAR) ranging from 400 to 700 nm; this includes blue and red light wavelengths. Although the influence of spectral quality is being investigated in diverse plant species, particularly, its importance in in vitro propagated horticultural crops is gaining notable interest among researchers. In recent days, the application of LEDs provides better amenability according to the plant species of interest for efficient plant regeneration. Considering the growing necessity and emerging applications of LED supplemental lights for propagation of plants in in vitro, the present review summarizes the outcomes of various research studies dealing with LEDs in plant tissue culture. Moreover, the present endeavor has provided a comprehensive overview on the effects of LEDs in the morphogenesis of plants cultured in vitro.

Molecular advances to study the function, evolution and spectral tuning of arthropod visual opsins.

Visual opsins of vertebrates and invertebrates diversified independently and converged to detect ultraviolet to long wavelengths (LW) of green or red light. In both groups, colour vision largely derives from opsin number, expression patterns and changes in amino acids interacting with the chromophore. Functional insights regarding invertebrate opsin evolution have lagged behind those for vertebrates because of the disparity in genomic resources and the lack of robust in vitro systems to characterize spectral sensitivities. Here, we review bioinformatic approaches to identify and model functional variation in opsins as well as recently developed assays to measure spectral phenotypes. In particular, we discuss how transgenic lines, cAMP-spectroscopy and sensitive heterologous expression platforms are starting to decouple genotype–phenotype relationships of LW opsins to complement the classical physiological-behavioural-phylogenetic toolbox of invertebrate visual sensory studies. We illustrate the use of one heterologous method by characterizing novel LW Gq opsins from 10 species, including diurnal and nocturnal Lepidoptera, a terrestrial dragonfly and an aquatic crustacean, expressing them in HEK293T cells, and showing that their maximum absorbance spectra (λmax) range from 518 to 611 nm. We discuss the advantages of molecular approaches for arthropods with complications such as restricted availability, lateral filters, specialized photochemistry and/or electrophysiological constraints.This article is part of the theme issue ‘Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods’.

Effect of wavelength on development and demographic parameters of Scolothrips longicornis fed on two-spotted spider mites

The wavelength of light can affect reproduction and development of arthropods. In the present study, we examined the reproduction and development of predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on Tetranychus urticae Koch (Trombidiformes: Tetranychidae) eggs, under five wavelengths: white (all wavelengths), blue (475 nm), green (580 nm), yellow (620 nm) and red (675 nm), at 25 ± 0.5 °C, 16L: 8D and 60 ± 10% rh. Light wavelength did not significantly influence female and male preadult duration, male adult duration, and male total longevity. White and blue light yielded the longest oviposition periods. All life table parameters varied significantly among treatments. The intrinsic rate of increase (rm d−1) was lowest in red light wavelength (0.112 ± 0.009) and highest in white wavelength (0.171 ± 0.008) and blue light wavelength (0.168 ± 0.008). The present research demonstrates that white light conditions positively influence S. longicornis with shorter development time and improved reproductive performance. This information will be beneficial in mass production of S. longicornis for biocontrol programs involving T. urticae.

Effect of Light-Emitting Diodes on Different Growth Stages of Rice

Effect of red and blue light on seed germination and seedling growth were studied in rice (Oryza sativa L.). Rice seeds were germinated in dark (control) and two types of light emitting-diodes (LED): red and green in the laboratory. The photoperiod of 6 h light and 18 h dark for LEDs treatment and 24h dark treatments with 24/18 ± 2 °C day/night temperature and 78± 2 % relative humidity were maintained in the growth room. Seed germination percentage under red light increased significantly when compared with the control; however, in blue light, germination percent decreased with little difference. First leaf length, first leaf blade length, root length, seedling fresh and dry weight increased under red and blue lights in most of the varieties. Highest germination (98%), longest root (8.18 cm) and high seedling fresh weight (0.527 g) and seedling dry weight (0.061g) in BRRIdhan71 and longest leaf in BRRIdhan75, were recorded under red light. Highest germination (96%), seedling fresh weight (0.414g) and seedling dry weight (0.047g) in BRRIdhan71, longest first leaf (6.50 cm) in BRRIdhan75 and longest root (9.37 cm) in BRRIdhan87 were recorded under blue light. First leaf blade showed only positive correlation with root length (r = 0.489), whereas seedling fresh weight showed complete correlation with seedling dry weight (r =1). Response index was positive in root length, seedling fresh and dry weight under red light. First leaf blade length, seedling fresh and dry weight had the positive response index under blue light. Within the visible spectrum, varying wave lengths of red and blue light alone altered the growth and morphology of rice seedlings, and variable reactions to illumination depended on the rice varieties, necessitating further research.&#x0D; Environ. Sci. &amp; Natural Resources, 13(1&amp;2): 56-62, 2020

Amorphous-silicon visible-light detector integrated on silicon nitride waveguides.

Visible-light integrated photonics is emerging as a promising technology for the realization of optical devices for applications in sensing, quantum information and communications, imaging, and displays. Among the existing photonic platforms, high-index-contrast silicon nitride (Si3N4) waveguides offer broadband transparency in the visible spectral range and a high scale of integration. As the complexity of photonic integrated circuits (PICs) increases, on-chip detectors are required to monitor their working point for reconfiguration and stabilization operations. In this Letter, we present a semi-transparent in-line power monitor integrated on Si3N4 waveguides that operates in the red-light wavelength range (660 nm). The proposed device exploits the photoconductivity of a hydrogenated amorphous-silicon (a-Si:H) film that is evanescently coupled to an optical waveguide. Experimental results show a responsivity of 30 mA/W, a sensitivity of -45 dBm, and a sub-µs time response. These features enable the use of the proposed photoconductor for high-sensitivity monitoring and control of visible-light Si3N4 PICs.

Phenotypic plasticity of Monilinia spp. in response to light wavelengths: From in vitro development to virulence on nectarines

The development of brown rot in stone fruit caused by the necrotrophic fungus Monilinia spp. is influenced by many abiotic factors, such as temperature, humidity, and light. Specifically, filamentous fungi perceive light as a signal for ecophysiological and adaptive responses. We have explored how specific light wavelengths affect the in vitro development, the regulation of putative development genes and the virulence of the main species of Monilinia (M. laxa, M. fructicola and M. fructigena). After subjecting Monilinia spp. to different light wavelengths (white, black, blue, red, far-red) for 7 days, several differences in their phenotype were observed among light conditions, but also among species. These species of Monilinia exhibited a different phenotypic plasticity in response to light regarding pigmentation, growth, and specially conidiation of colonies. In this sense, we observed that the conidial production was higher in M. laxa than M. fructicola, while M. fructigena showed an inability to produce conidia under the tested conditions. Growth rate among species was significantly lower in M. fructicola under red light wavelength while among light conditions it was increased under far-red light wavelength for M. laxa and under black light for M. fructicola; in contrast, no statistical differences were observed for M. fructigena. Gene expression analysis of 13 genes involved in fungal development of Monilinia spp. revealed a significant difference among the three species of Monilinia, and especially depended on light wavelengths. Among them, a high expression of OPT1, RGS2, RGS3 and SPP1 genes was observed in M. laxa, and LTF1 and STE12 in M. fructicola under black light. In contrast, a high expression of REG1 and C6TF1 genes occurred in both M. fructicola and M. laxa subject to red and far-red light wavelength, respectively. When nectarines were artificially infected with M. laxa and M. fructicola subjected to black light, the virulence was clearly reduced, but not in M. fructigena. Overall, results presented herein demonstrate that light wavelengths are a key abiotic factor for the biology of Monilinia spp., specially modulating its capacity to form conidia, and thus, influencing its spreading and the onset of the disease on nectarines during postharvest.

Photobiomodulation Modulates Interleukin-10 and Interferon Gamma Production by Mononuclear Cells from Healthy Donors and Persons with Multiple Sclerosis.

Background: Photobiomodulation (PBM) therapy was previously shown to reduce the clinical severity of disease and modulated pro- and anti-inflammatory cytokines in an animal model of multiple sclerosis (MS). Objective: Previous observations were extended to determine the effect of PBM therapy on peripheral blood mononuclear cells and CD4+ T cells isolated from persons with MS (PwMS) and healthy donors. Methods: Using an in vitro cell culture system, isolated cells were activated and treated with red or near-infrared light wavelengths to determine the effect of PBM on the production of interferon gamma and interleukin-10 (IL-10). Results: PBM modulated cytokine production in MS subjects and healthy donors in a dose- and wavelength-dependent manner, with MS subjects and healthy donors responding differently to administered light. In addition, disease severity affected the response of immune cells, for instance, 670 nm increased IL-10 production associated with increased disease severity. Conclusions: The data show that PBM therapy has the potential to modulate pro- and anti-inflammatory cytokines in PwMS over the course of disease. Further experiments applying PBM treatment directly on patients should be carried out with extreme caution to avoid severe imbalance in the immune response.

A new series of long wavelength red phosphors BaLaLiTe1-xO6:xMn4+ for plant cultivation LED

Mn4+ doped phosphors have been attracted more and more attention because their emitting spectra can be absorbed by chlorophyll or phytochrome (Pr and Pfr) of plants. Herein, we prepared a new series of phosphors BaLaLiTe1-xO6:xMn4+ (BLLT:xMn4+, x = 0.002–0.014) by solid state reaction method. Their structure and phase purity were verified by X-ray diffraction (XRD) analysis. Under 336 nm exciting, BLLT:xMn4+ can emit long wavelength red light at around 700 nm, which fits well with the Pfr spectra of plants. The Mn4+ concentration was optimized to be x = 0.01, and when it was exceeded, concentration quenching would occur. The internal (IQE) and external quantum efficiency (EQE) of BLLT:0.01Mn4+ were measured to be 32% and 23% by direct method. Besides, the BLLT:0.01Mn4+ possesses good thermostability, remaining 76% of the integrated intensity at 423 K of that at 298 K. Hence, we think BLLT:0.01Mn4+ have potentially applications for plant growth LED.

Enhanced performance of GaN-based visible flip-chip mini-LEDs with highly reflective full-angle distributed Bragg reflectors

High-efficiency GaN-based visible flip-chip miniaturized-light emitting diodes (FC mini-LEDs) are desirable for developing white LED-backlit liquid crystal displays. Here, we propose a full-angle Ti3O5/SiO2 distributed Bragg reflector (DBR) for blue and green FC mini-LEDs to enhance the device performance. The proposed full-angle Ti3O5/SiO2 DBR is composed of different single-DBR stacks optimized for central wavelength in blue, green, and red light wavelength regions, resulting in wider reflective bandwidth and less angular dependence. Furthermore, we demonstrate two types of GaN-based FC mini-LEDs with indium-tin oxide (ITO)/DBR and Ag/TiW p-type ohmic contacts. Experimental results exhibit that the reflectivity of full-angle DBR is higher than that of Ag/TiW in the light wavelength range of 420 to 580 nm as the incident angle of light increases from 0° to 60°. As a result, the light output powers (LOPs) of blue and green FC mini-LEDs with ITO/DBR are enhanced by 7.7% and 7.3% in comparison to blue and green FC mini-LEDs with Ag/TiW under an injection current of 10 mA. In addition, compared with FC mini-LED with Ag/TiW, light intensity of FC mini-LED with ITO/DBR is improved in side direction, which is beneficial to mix light in backlight system of liquid crystal displays (LCDs).

Crystalline phase formation of Na2W2O7 using microwave-assisted solution combustion synthesis for photocatalytic degradation of organic pollutants from aqueous solutions

A novel combustion method, microwave assisted solution combustion (MASC), was first employed to synthesis Na2W2O7 nanoparticles, which were characterized by photoluminescence analysis (PL), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The PL of prepared samples demonstrated a green emission, which was not reported before for this product prepared using the combustion method. Also, to improve the luminescence and photocatalytic properties of these particles, europium element was doped on Na2W2O7 structure that the emission peak of host crystals was shifted to the red-light wavelength. Photocatalytic activities of the Na2W2O7 synthesized crystals were studied and the Genetic Algorithm (GA) method was used to optimize the photodegradation process using the response surface methodology (RSM). To recognize the advanced models adequacy and reveal good agreement between the offered model and the experimental data, statistical analysis of variance (ANOVA) was performed. Based on the results, technologically advanced catalytic treatment and models can be used effectively to remove organic pollutants consisting of AZO bonds from water supplies.