Effects of Violet and IR LED Light on mast cell degranulation: in vivo study in a murine model

The aim of this study was to evaluate the influence of IR (λ850 ± 10 nm) and violet (λ405 ± 10 nm) LED phototherapy on total mast cells counts and its ability to influence mast cell degranulation. For this, 27 Wistar rats were used and were randomly distributed into three groups: control, IR LED, and violet LED. When indicated, irradiation done and they were sacrificed, had their tongue removed immediately, 20-min, 45-min, and 2-h after irradiation. Samples were processed to wax, cut, and stained with Toluidine Blue. Intact and degranulated mast cells were counted under light microscopy, and statistical analysis was carried out. In the superficial connective tissue and muscular tissues, violet LED light caused a significant increase in both total number and degranulated mast cells when compared to the control group immediately after irradiation. The degranulation indexes were higher in the groups irradiated with Violet light, both in superficial connective tissue and muscular tissues in relation to the timing. Irradiation with IR LED caused immediate increase in the total number and degranulated of mast cells when compared to the control group only in the superficial connective tissue. In all times observed, the highest total amount of mast cells was seen immediately after irradiation, except in the muscular tissue, which presented the highest amount after 20-min. It was concluded that IR and violet LED light were able to increase the number of mast cells and inducing degranulation in oral mucosa. However, considering that violet LED light can be harmful in periodontal disease, it seems that the use of IR LED light could be the best option in Dentistry.

Antimicrobial activity and drying potential of high intensity blue light pulses (455 nm) emitted from LEDs

Decontamination of low water activity (a_w) foods, like pet foods is a challenging task. Treatment using light emitting diode (LED) is an emerging decontamination method, that can induce photodynamic inactivation in bacteria. The objective of this study was to understand the effect of selected product and process parameters on the antibacterial efficacy of treatment using light pulses of 455 nm wavelength on dry powdered Salmonella and pet foods equilibrated to 0.75 a_w. The surface temperature increase, weight loss, and a_w decrease in the samples were determined after LED treatments with different doses. S. Typhimurium on pet foods showed better sensitivity to 455 nm LED treatment than the powdered S. Typhimurium. For instance, 455 nm LED treatment with 785.7 J/cm² dose produced a log reduction of 1.44 log (CFU/g) in powdered S. Typhimurium population compared to 3.22 log (CFU/g) on pet food. The LED treatment was less effective against 5-strain cocktail of Salmonella in low a_w pet foods. The treated samples showed significant reduction in weight and a_w showing the heating and drying potential of 455 nm LED treatment. Significant lipid oxidation was observed in the treated pet foods. Overall, the dose, treatment time, and sample type influenced the Salmonella inactivation efficacy of 455 nm LED treatment in low a_w conditions.

The effect of different colored light emitting diode illumination on egg laying performance, egg qualities, blood hormone levels and behavior patterns in Brown Tsaiya duck

Objective

The objective of this experiment was to investigate the effects of different colors produced by light emitting diode (LED) on Brown Tsaiya ducks.

Methods

A total of 144 female Brown Tsaiya ducks were randomly allocated into three individual cage rearing chambers with different LED illumination colors as treatments. Three different treatments were: i) white color, ii) blue color, and iii) red color. The experiment periods were from ducks 21 to 49 weeks of age, determined traits included i) egg laying performance, ii) feed intake, iii) egg shell breaking strength, iv) egg shell thickness, v) egg Haugh unit, vi) egg weight, vii) serum Estradiol and Progesterone concentration, and viii) behavior pattern.

Results

The results indicated that when compared with white and blue color, red color could stimulate ducks sexual maturation and raised the egg laying performance. The red light group was also observed to have the highest feed intake among three treatments. The blue treatment had the lowest egg shell breaking strength and the highest egg weight among three treatments, nevertheless, no significant difference was observed among three treatments on egg shell thickness and egg Haugh unit. The red light group had higher serum estradiol concentration than the white and blue groups, but no significant difference among treatments on the serum Progesterone concentration was found. The results of behavior pattern indicated that red light group showed more feeding and less resting behavior compared to the blue light group.

Conclusion

We found a potential of applying red light illumination in the indoor laying duck raising system with positive results on egg laying performance and acceptable egg weight, equivalent egg qualities compared to white and blue light.

Optical simulations for determining efficacy of new light source designs for excitation-scanning high-speed hyperspectral imaging systems

Positive outcomes for colorectal cancer treatment have been linked to early detection. The difficulty in detecting early lesions is the limited contrast with surrounding mucosa and minimal definitive markers to distinguish between hyperplastic and carcinoma lesions. Colorectal cancer is the 3rd leading cancer for incidence and mortality rates which is potentially linked to missed early lesions which allow for increased growth and metastatic potential. One potential technology for early-stage lesion detection is hyperspectral imaging. Traditionally, hyperspectral imaging uses reflectance spectroscopic data to provide a component analysis, per pixel, of an image in fields such as remote sensing, agriculture, food processing and archaeology. This work aims to acquire higher signal-to-noise fluorescence spectroscopic data, harnessing the autofluorescence of tissue, adding a hyperspectral contrast to colorectal cancer detection while maintaining spatial resolution at video-rate speeds. We have previously designed a multi-furcated LED-based spectral light source to prove this concept. Our results demonstrated that the technique is feasible, but the initial prototype has a high light transmission loss (~98%) minimizing spatial resolution and slowing video acquisition. Here, we present updated results in developing an optical ray-tracing model of light source geometries to maximize irradiance throughput for excitation-scanning hyperspectral imaging. Results show combining solid light guide branches have a compounding light loss effect, however, there is potential to minimize light loss through the use of optical claddings. This simulation data will provide the necessary metrics to verify and validate future physical optical components within the hyperspectral endoscopic system for detecting colorectal cancer.

Inactivation of Escherichia Coli and Salmonella Using 365 and 395 nm High Intensity Pulsed Light Emitting Diodes

High intensity pulsed light emitting diode (LED) treatment is a novel approach to inactivate foodborne pathogens. The objective of this study was to evaluate the antibacterial potential of high intensity 365 (UV-A) and 395 nm (NUV-Vis) LED treatments against Escherichia coli and Salmonella enterica at high and low water activity (a_w) conditions, and to understand the influence of different process parameters on their antibacterial efficacy. Bacteria at high (in phosphate buffer saline, PBS) and low a_w (a_w = 0.75) conditions were treated with both the LEDs with specific doses at a fixed distance from the LEDs. The 365 nm LED showed more effectiveness in reducing the dried bacteria compared to 395 nm LED. The dry E. coli showed more resistance to LED treatments compared to Salmonella. The 365 and 395 nm LED treatments with ~658 J/cm² dose resulted in reductions of 0.79 and 1.76 log CFU/g of Salmonella, respectively, on 0.75 a_w pet foods. The LED treatments increased the surface temperature, resulting in water loss in the treated samples. This study showed that the dose, duration of light exposure, bacterial strain, and a_w played a major role in the antibacterial efficacy of the 365 and 395 nm LEDs.

Sensitivity analysis of a multibranched light guide for real time hyperspectral imaging systems

Hyperspectral imaging (HSI) is a spectroscopic technique which captures images at a high contrast over a wide range of wavelengths to show pixel specific composition. Traditional uses of HSI include: satellite imagery, food distribution quality control and digital archaeological reconstruction. Our lab has focused on developing applications of HSI fluorescence imaging systems to study molecule-specific detection for rapid cell signaling events or real-time endoscopic screening. Previously, we have developed a prototype spectral light source, using our modified imaging technique, excitation-scanning hyperspectral imaging (HIFEX), coupled to a commercial colonoscope for feasibility testing. The 16 wavelength LED array was combined, using a multi-branched solid light guide, to couple to the scope's optical input. The prototype acquired a spectral scan at near video-rate speeds (∼8 fps). The prototype could operate at very rapid wavelength switch speeds, limited to the on/off rates of the LEDs (∼10 μs), but imaging speed was limited due to optical transmission losses (∼98%) through the solid light guide. Here we present a continuation of our previous work in performing an in-depth analysis of the solid light guide to optimize the optical intensity throughput. The parameters evaluated include: LED intensity input, geometry (branch curvature and combination) and light propagation using outer claddings. Simulations were conducted using a Monte Carlo ray tracing software (TracePro). Results show that transmission within the branched light guide may be optimized through LED focusing lenses, bend radii and smooth tangential branch merges. Future work will test a new fabricated light guide from the optimized model framework.

Photoreceptor spectral sensitivity of the compound eyes of black soldier fly (Hermetia illucens) informing the design of LED-based illumination to enhance indoor reproduction

Mating in the black soldier fly (BSF) is a visually mediated behaviour that under natural conditions occurs in full sunlight. Artificial light conditions promoting mating by BSF were designed based on the spectral characteristics of the compound eye retina. Electrophysiological measurements revealed that BSF ommatidia contained UV-, blue- and green-sensitive photoreceptor cells, allowing trichromatic vision. An illumination system for indoor breeding based on UV, blue and green LEDs was designed and its efficiency was compared with illumination by fluorescent tubes which have been successfully used to sustain a BSF colony for five years. Illumination by LEDs and the fluorescent tubes yielded equal numbers of egg clutches, however, the LED illumination resulted in significantly more larvae. The possibilities to optimize the current LED illumination system to better approximate the skylight illuminant and potentially optimize the larval yield are discussed.

Impact of light quality on biomass production and fatty acid content in the microalga Chlorella vulgaris

In this study, the green microalga Chlorella vulgaris was exposed to monochromatic light at six different wavelengths in order to study the effect on biomass productivity and fatty acid content. A significantly higher amount of biomass by produced in the treatments with yellow, red and white light compared with blue, green and purple light. There were also significant differences in total lipid content and fatty acid profile between the treatments. The green light regime gave the lowest concentration of lipids, but increased the concentration of polyunsaturated fatty acids. Thus it can be concluded that light quality significantly affects biomass productivity, total lipid concentration and fatty acid profile in the microalga C. vulgaris.