High-intensity Light-emitting Diode Research Articles

Sapphire-Based Optrode for Low Noise Neural Recording and Optogenetic Manipulation.

Electrophysiological recordings of neurons in deep brain regions using optogenetic stimulation are essential to understanding and regulating the role of complex neural activity in biological behavior and cognitive function. Optogenetic techniques have significantly advanced neuroscience research by enabling the optical manipulation of neural activities. Because of the significance of the technique, constant advancements in implantable optrodes that integrate optical stimulation with low-noise, large-scale electrophysiological recording are in demand to improve the spatiotemporal resolution for various experimental designs and future clinical applications. However, robust and easy-to-use neural optrodes that integrate neural recording arrays with high-intensity light emitting diodes (LEDs) are still lacking. Here, we propose a neural optrode based on Gallium Nitride (GaN) on sapphire technology, which integrates a high-intensity blue LED with a 5x2 recording array monolithically for simultaneous neural recording and optogenetic manipulation. To reduce the noise interference between the recording electrodes and the LED, which is in close physical proximity, three metal grounding interlayers were incorporated within the optrode, and their ability to reduce LED-induced artifacts during neural recording was confirmed through both electromagnetic simulations and experimental demonstrations. The capability of the sapphire optrode to record action potentials has been demonstrated by recording the firing of mitral/tuft cells in the olfactory bulbs of mice in vivo. Additionally, the elevation of action potential firing due to optogenetic stimulation observed using the sapphire probe in medial superior olive (MSO) neurons of the gerbil auditory brainstem confirms the capability of this sapphire optrode to precisely access neural activities in deep brain regions under complex experimental designs.

Photosynthesis of C-1-Deuterated Aldehydes via Chlorine Radical-Mediated Selective Deuteration of the Formyl C-H Bond.

C-1-deuterated aldehydes are essential building blocks in the synthesis of deuterated chemicals and pharmaceuticals. This has led chemists to devise mild methodologies for their efficient production. Ideally, hydrogen-deuterium exchange (HDE) is the most effective approach. However, the traditional HDE for creating C-1-deuterated aldehydes often requires a complex system involving multiple catalysts and/or ligands. In this study, we present a mild photocatalytic HDE of the formyl C-H bond with D2O. This process is facilitated by chlorine radicals that are generated in situ from low-cost FeCl3. This strategy demonstrated a broad reaction scope and high functional group tolerance, affording good yields and ≤99% D incorporation. To bridge the gap between research and industrial applications, we designed a new flow photoreactor equipped with a high-intensity light-emitting diode bucket, enabling the synthesis of C-1-deuterated aldehydes on a scale of 85 g. Finally, we successfully produced several important deuterated aldehydes that are integral to the synthesis of deuterated pharmaceuticals.

An In-Vitro Comparison of Shear Bond Strength and Adhesive Remnant Score Between Two Color Change Adhesives in Orthodontic Bonding With Reduced Curing Time Using Different High-Intensity Light Emitting Diode Units.

This study aims to determine the effect on shear bond strength (SBS) and adhesive remnant score between two color change adhesives (CCAs) with reduced curing time using different high-intensity light emitting diode(LED) units. A total of 108 human first maxillary premolar teeth were randomly allocated into three principal groups (n = 36) based on the type of adhesives used. The adhesives include two CCAs: TransbondPlus Color Change Adhesive (3M, St. Paul, MN, USA) and Grengloo (Ormco, Orange, CA, USA), and the conventional tooth-colored adhesive: TransbondXT (3M). Each principal group was further divided into three sub-groups (n = 12 each) based on the curing time and type of high-intensity LED units used for bonding the stainless steel brackets. Woodpecker iLED Light Curing Unit (Guilin Woodpecker Medical Instrument Co., Ltd., Guilin, China) was cured for three and six seconds, and the ELIPARS10 LED Curing Light (3M) was cured for 20 seconds. Bonding of the brackets was done in a standardized manner following the manufacturers' instructions. All the samples were submerged in distilled water at 370C for 24 hours. SBS testing was performed using an Instron machine, and adhesive residue on the debonded surface was examined and scored using a stereomicroscope. Statistical analysis was conducted using one-way ANOVA and Tukey's post-hoc test. The results showed significant differences in SBS based on curing time and the type of adhesive resin used. The six seconds curing group exhibited the higher SBS values (15.5 - 22.82 Megapascals [MPa]) followed by the 20 seconds (12.17 - 18.14 MPa) and three seconds (11.31 - 11.74 MPa) groups. Grengloo adhesive demonstrated the highest SBS values among the three types of adhesives. The predominant adhesive remnant scores were 2 and 3. Grengloo adhesive demonstrates superior bond strength compared to Transbond Plus and Transbond XT. Both Transbond Plus and Grengloo adhesives experience bond failure within the adhesive layer, regardless of the curing intensity or time.

Effect of Different Light-tip Distances on Shear Bond Strength of Orthodontic Brackets Cured with Light-emitting Diode and High-intensity Light-emitting Diode.

The aim was to find out whether the light-tip distance affected the shear bond strength of orthodontic brackets when cured with light-emitting diode (LED) and high-intensity LED at four different light-tip distances. Extracted human premolars were divided into eight groups. Each tooth was embedded in the self-cure acrylic resin block, and brackets were bonded and cured with different lights and different distances. Shear bond strength tests were performed in vitro using the universal testing machine. Data were analyzed using one-way ANOVA test. The descriptive statistics for shear bond strength of orthodontic brackets cured with LED light at 0 mm was 8.49 ± 1.08 MPa, at 3 mm was 8.13 ± 0.85 MPa, 6 mm was 6.42 ± 0.42 MPa, and at 9 mm was 5.24 ± 0.92 MPa, and those cured with high-intensity light at 0 mm was 19.23 ± 4.83 MPa, at 3 mm was 17.65 ± 3.28 MPa, at 6 mm was 13.04 ± 2.36 MPa, and at 9 mm was 11.74 ± 1.4 MPa. Mean shear bond strength was found to decrease as the light-tip distance increased with both light sources. Shear bond strength is higher when the light source is close to the surface to be cured, and it decreases as the distance increases. The highest shear bond strength was achieved with high-intensity light. Light-emitting diode or high-intensity units can be used for bonding orthodontic brackets without compromising the shear bond strength of the brackets, and that shear bond strength is stronger when the light source is close to the surface to be cured, and it decreases as the distance increases between the light source and the surface.

Lighting a Path for Autonomous Vehicle Communication: The Effect of Light Projection on the Detection of Reversing Vehicles by Older Adult Pedestrians.

Pedestrian understanding of driver intent is key to pedestrian safety on the road and in parking lots. With the development of autonomous vehicles (AVs), the human driver will be removed, and with it, the exchange that occurs between drivers and pedestrians (e.g., head nods, hand gestures). One possible solution for augmenting that communication is an array of high-intensity light-emitting diodes (LEDs) to project vehicle-to-pedestrian (V2P) messages on the ground plane behind a reversing vehicle. This would be particularly beneficial to elderly pedestrians, who are at particular risk of being struck by reversing cars in parking lots. Their downward gaze and slower reaction time make them particularly vulnerable. A survey was conducted to generate designs, and a simulator experiment was conducted to measure detection and reaction times. The study found that elderly pedestrians are significantly more likely to detect an additional projected message on the ground than detect the existing brake light alone when walking in a parking lot.

Comparative evaluation of shear bond strength of directly bonded brackets using three varieties of light cure systems

Context: Using Visible Light to bond orthodontic attachments is now an accepted norm, the progression being Halogens, Low and High Intensity Light Emitting Diodes (LEDs). Since, clinical use of bonded brackets is pragmatically linked with Shear Bond Strength (SBS) and chair-side time, adhesives with shorter curing time are a boon. Hence, the aforementioned facets bear a more detailed study. Settings and Design: 6 Groups (2 Halogens, 2 Low Intensity LEDs and 2 High Intensity LEDs); Each Group comprised of 10 assemblies of Metal Brackets (3M Unitek, Gemini Series) bonded to facial surface of extracted human Maxillary 1st bicuspids. Methods and Material: Brackets were directly bonded using Standard Bonding Protocol to freshly extracted Human Maxillary Premolars. Shear Bond Strength (SBS) testing was done using Universal Testing Machine, Instron. The SBS values attained in Kg/F were converted into MPa and results subjected to a comparative evaluation. Results: Mean SBS values, in MPa, for Halogen Light Cure Systems were 8.51 and 8.86; for Low Intensity LEDs were 10.50 and 10.33 while for High Intensity LEDs 15.54 and 13.85.

Effect of Light-emitting Diodes, Ultraviolet-B, and Fluorescent Supplemental Greenhouse Lights on Strawberry Plant Growth and Response to Infection by the Anthracnose Pathogen Colletotrichum gloeosporioides

Supplemental lighting is frequently used to extend daylength for strawberries (Fragaria ×ananassa) grown in greenhouses and high tunnels; however, information is limited on the effect of these lights on disease development. We evaluated the effect of ambient light and six supplemental light treatments [red, blue, and white light-emitting diodes (LEDs), separately; a combination of red, blue, and white LEDs; wide-spectrum fluorescent (WSF); and WFS + ultraviolet B (UV-B)] on plant growth and disease response of strawberries grown in a greenhouse. Plants were exposed to supplemental light treatments for 17 h each day. In the WSF+UV-B treatment, plants were exposed to WSF light during the day and to UV-B light for 3 hours during the night. Two trials were conducted; each trial contained five or six cultivars and was replicated three times. Twice during each trial, detached leaves from each cultivar in each light treatment were inoculated with a conidial suspension of the anthracnose crown rot pathogen, Colletotrichum gloeosporioides and rated for disease severity 10 days later. There was a significant difference due to light treatment and to cultivar in relative chlorophyll content and plant growth parameters. Plant injury ratings were lowest in the white LED, WSF, and WSF+UV-B treatments. Plants in the combination LED and red LED light treatments received higher injury, lower vigor scores, and lower relative chlorophyll content values than plants in all other light treatments. After inoculation of detached strawberry leaves with C. gloeosporioides in Trial 1, there was a significant effect due to light treatments on disease severity ratings (DSRs) after 18 weeks’ exposure to light treatments with the DSRs in the WSF+UV-B treatment being lower than those in all other treatments except those in the red LED treatment. There was not a significant effect in DSRs due to light treatments after 24 weeks in Trial 1 or after 4 or 22 weeks in Trial 2. There were significant effects due to cultivar on DSRs in both trials: ‘Strawberry Festival’, ‘Pelican’, and ‘Seascape’ received the lowest DSRs. This study showed an effect of supplemental light on several strawberry plant growth parameters, including a harmful effect of high-intensity red LED irradiation.

High-Intensity Red Light-Emitting Diode Irradiation Suppresses the Inflammatory Response of Human Periodontal Ligament Stem Cells by Promoting Intracellular ATP Synthesis.

Periodontitis is an inflammatory lesion in the periodontal tissue. The behavior of human periodontal ligament stem cells (hPDLSCs), which play an important role in periodontal tissue regeneration, is restricted by the influence of inflammatory mediators. Photobiomodulation therapy exerts anti-inflammatory effects. The purpose of this study was to investigate the effects of light-emitting diode (LED) irradiation on the inflammatory responses of hPDLSCs. The light source was a red LED (peak wavelength: 650 nm), and the total absolute irradiance was 400 mW/cm2. The inflammatory response in hPDLSCs is induced by tumor necrosis factor (TNF)-α. Adenosine triphosphate (ATP) levels and pro-inflammatory cytokine (interleukin [IL]-6 and IL-8) production were measured 24 h after LED irradiation, and the effects of potassium cyanide (KCN) were investigated. LED irradiation at 6 J/cm2 significantly increased the ATP levels and reduced TNF-α-induced IL-6 and IL-8 production. Furthermore, the inhibitory effect of LED irradiation on the production of pro-inflammatory cytokines was inhibited by KCN treatment. The results of this study showed that high-intensity red LED irradiation suppressed the TNF-α-stimulated pro-inflammatory cytokine production in hPDLSCs by promoting ATP synthesis. These results suggest that high-intensity red LED is a useful tool for periodontal tissue regeneration in chronically inflamed tissues.

High-Intensity Light-Emitting Diode and Reduced Curing Times—An In Vitro Study

Objective: To evaluate and compare the effect of high-intensity light-emitting diode (LED) light-curing unit at different curing times on the shear bond strength (SBS), surface enamel loss, and degree of polymerization of a light-cure and dual-cure adhesive system. Materials and Methods: One hundred and twenty extracted human premolar teeth were divided into 2 groups— group 1 (light cure) and group 2 (dual cure), depending on the adhesive system used. These groups were further subdivided into 3 subgroups with 20 teeth each, depending on the duration of curing. A high-intensity LED curing unit was used to bond metal brackets onto the teeth. The samples were tested on a universal testing machine to measure the SBS. The samples were then observed under a simple microscope and modified adhesive remnant index scores were assigned. The bracket bases were mapped with energy-dispersive X-ray spectrometry to evaluate the amount of enamel present. Cured adhesive was scraped and was subjected to Fourier-Transform Infrared Spectroscopy to assess the degree of cure (%DC). Results: An increase in curing durations increased mean SBS values, %DC, and calcium-phosphorous ratios (Ca:P). Similarly, these parameters were higher for dual-cure subgroups when compared to light-cure subgroups. Conclusion: High-intensity LEDs can be used successfully for bonding orthodontic brackets with reduced curing duration. These LEDs help to reduce chairside time and can minimize damage to enamel without compromising bond strength.

High intensity and red enriched LED lights increased the growth of lettuce and endive

Changes in plant responses have been associated with different fractions of the visible spectrum and light intensity. Advances in light-emitting diodes (LED) have enabled the study of the effect of narrow wavelengths on plant growth and antioxidant compound synthesis. LED technology also facilitates the incorporation of light sources in a controlled setting where light spectra and intensity can be regulated. The objective of this study was to compare the effect of two commercial light spectra (S1: standard white light with 32.8% blue, 42.5% green, 21.7% red, and 2.4% far-red; S2: AP67 spectrum, designed for horticultural growth, with 16.9% blue, 20.5% green, 49.7% red and 12.3% far red) at two light intensities [low intensity (78 μmol m–2s–1 of photons for S1 and 62 μmol m–2s–1 for S2, and high intensity (HI) (102 and 100 μmol m–2s–1 for S1 and S2, respectively)] on growth and antioxidant compound contents in two leafy vegetables: endive (Cichorium endivia L.) and lettuce (Lactuca sativa L.). Fresh weight (FW), dry weight (DW), and DW% of plants were taken as growth indicators. In addition, leaf number, soil plant analysis development index, leaf area (LA), and specific leaf area were also evaluated. Antioxidant synthesis was measured as total phenol content, total flavonoid content, and antioxidant activity. The results showed that S2 and HI increased the FW, DW, and LA in both species. On the other hand, antioxidant compound contents were significantly increased by HI but did not vary with the spectrum. Highlights - The spectra of LED affected leaf number in lettuce and endive. - S2 spectrum improved growth parameters of both leafy vegetables. - Light intensity improved growth parameters of both leafy vegetables. - Antioxidant compound contents were significantly increased by high intensity LED light.

Retinal damage related to high-intensity light-emitting diode exposure: An in vivo study

The objective of this investigation was to evaluate the effects of high-intensity light-emitting diode (LED) light from a curing device on the retinas of Wistar rats. Six male Wistar rats were used, and their ocular structures were the focus of this study. During the photostimulation of each animal, the right eye of the animal, considered the control sample, was covered with a removable polyvinyl chloride cap, and the contralateral eye, the experimental sample, was exposed to high-intensity LED light, 3200 mW/cm2 (VALO Ortho; Ultradent Products, South Jordan, Utah) for 144 seconds from a distance of 30 cm. The animals were exposed to the LED light 3 times on the same day to investigate if any acute inflammatory changes in the retina occurred. Seven days after the photostimulation sessions, the animals were anesthetized and perfused with paraformaldehyde solution. After which, the eyes were resected and processed histologically. The histologic sections were analyzed stereologically and histomorphometrically to measure the parameters of the retina under investigation. There was a statistically significant increase in total retinal volume in the experimental group because of the increased volume of the ganglion cell layers, inner plexiform layers, outer nuclear layers, and the cone and rod extensions. There was no statistically significant difference in terms of density. However, there was a statistically significant increase in the nuclear area of the cells in all the studied layers in the group exposed to high-intensity LED light. In addition, hyperchromatic cells that are suggestive of pyknosis were observed. An acute but short protocol of exposure of high-intensity LED light to the eye caused morphometric alterations in the retinal structures, specifically in the nuclear area of the photosensitive cells.

Control of Burn Wound Infection by Methylene Blue-Mediated Photodynamic Treatment With Light-Emitting Diode Array Illumination in Rats.

Control of burn wound infection is difficult due to the increase in drug-resistant bacteria and deteriorated immune responses. In this study, we examined the usefulness of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT) with illumination by a light-emitting diode (LED) array for controlling invasive infections from the wound to inside the body for rats with an extended deep burn infected with Pseudomonas aeruginosa. An MB solution with the addition of ethanol, ethylene-diamine-tetra-acetic acid disodium salt, and dimethyl sulfoxide was used as a photosensitizer (PS). An extended deep burn was made on the dorsal skin in rats and the wounds were infected with P. aeruginosa. The rats were divided into three groups: control (no treatment; n = 14), PS mixture application alone (PS alone group; n = 10), and aPDT group (n = 14). For aPDT, after the PS mixture was applied onto the surface of infected wounds, the wounds were illuminated with a 665-nm LED array at an intensity of 45 mW/cm2 three times per treatment, with an illumination duration of 20 minutes and an interval of 10 minutes. The treatment was repeated each day for 7 consecutive days (day 0-day 6). Bacterial numbers on the wound surface and the weights and survival rates of the animals were evaluated daily. At the endpoints, bacterial numbers in the liver and blood were counted. Since the PS mixture showed high dark toxicity against P. aeruginosa in vitro, the influence of the PS mixture application onto healthy skin was also examined in vivo. Even in the aPDT group, rapid bacterial regrowth was observed on the wound surface after each day's treatment, but the geometric mean values of the bacterial numbers before and after each aPDT were considerably lower than those in the control group. Application of the PS mixture alone showed a clear bactericidal effect only at day 0, which is attributable to the formation of biofilms after day 1. Rats in the aPDT group showed a smaller weight loss, a higher ratio of no bacterial migration at the endpoints, and significantly higher survival rates than those in the other two groups. Effects of repeated application of the PS mixture onto healthy skin were not evident. Application of MB-mediated aPDT with illumination by a high-intensity LED array daily for seven consecutive days was effective for suppressing invasive infection from the wound to inside the body in rats with an extensive deep burn infected with P. aeruginosa, resulting in significant improvement of their survival. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Ni-Cu Nanoparticles-Embedded Ag-Based Reflector for High-Efficiency Light-Emitting Diodes.

We investigated the use of a silver reflector embedded with Ni-Cu nanoparticles to achieve low resistance and high reflectivity in GaN-based flip-chip light-emitting diodes. Compared to a single layer of Ag, the NC-NPs/Ag reflector exhibits a higher light reflectance of ~90% at a wavelength of 450 nm, a lower contact resistance of 4.75 × 10-5 II cm², and improved thermal stability after annealing at 400°C. The NC-NPs formed after the annealing process prevents agglomeration of the Ag layer, while also reducing the Schottky barrier height between the p-GaN layer and metal reflector. The LED fabricated with a NC-NPs/Ag reflector exhibited a forward-bias voltage of 3.13 V and an improvement in light output power of 36.6% (at 20 mA), when compared with the LED composed of a Ag SL. This result indicates that the NC-NPs/Ag reflector is a promising p-type reflector for high-intensity light-emitting diodes.

Irradiation by high-intensity red light-emitting diode enhances human bone marrow mesenchymal stem cells osteogenic differentiation and mineralization through Wnt/β-catenin signaling pathway.

Photobiomodulation therapy (PBMT) using a light-emitting diode (LED) has been employed for various photomedicine studies. The aim of this study was to determine the effects of a high-intensity red LED on the proliferation and osteogenic differentiation of human bone marrow mesenchymal stem cells (BMSCs) and the related mechanism. BMSCs were subjected to high-intensity red LED (LZ1-00R205 Deep Red LED) irradiations for 0 to 40s with energy densities ranging from 0 to 8J/cm2. The distance from the LED to the cell layer was 40mm. The spot size on the target was 4cm2. Cell proliferation was measured at 3, 24, 48, and 72h. The effects of LED irradiation on osteogenic differentiation and mineralization were examined with a particular focus on the Wnt/β-catenin signaling pathway. The high-intensity red LED irradiations did not alter BMSC proliferation after 72h. LED exposure of 6J/cm2 (30s) led to significant enhancements of osteogenic differentiation and mineralization. Additionally, the high-intensity LED irradiation induced activation of Wnt/β-catenin. The effects of the high-intensity LED irradiation on BMSC osteogenic differentiation and mineralization were suppressed by treatment with the Wnt/β-catenin inhibitor XAV939. P < 0.05 was considered significant. The results indicate that high-intensity red LED irradiation increases BMSC osteogenic differentiation and mineralization via Wnt/β-catenin activation. Therefore, short duration irradiation with a portable high-intensity LED may be used as a potential approach in hard tissue regeneration therapy.

Failure rates among metal brackets cured with two high-intensity LED light-curing lamps: an in vivo study.

The objective of this split-mouth clinical trial was to compare bonding failure rates of metal brackets bonded with two different light-emitting diode (LED) light-curing lamps with different high-intensity power outputs. Forty patients were included for a total of 800 brackets that were randomly bonded (left and right sides in a 1:1 ratio) in maxillary and mandibular arches using two different LED devices. An LED of 3200 mW/cm2 and an LED of 5000 mW/cm2 were used in this split-mouth clinical trial. Bonding failures during the initial 6 months of orthodontic treatment were recorded as maxillary versus mandibular, anterior teeth versus posterior teeth, and left side versus right side. Five dropouts were recorded for discontinuing orthodontic treatment and 700 brackets were analysed in total. The bonding failure rates for 3200 and 5000 mW/cm2 LEDs were 6.0 and 7.4 per cent, respectively (P = 0.450), which were not statistically significantly different. There were no significant differences in bracket survival rates between the LEDs used (P = 0.866). The posterior teeth presented a higher index of bond failures (odds ratio, 3.14; 95% confidence interval, 1.68-5.87; P < 0.001). Direct comparison was only done between two high-intensity LED lights rather than against conventionally used halogen lights. Similar bonding failures were recorded using both LED devices (3200 and 5000 mW/cm2). Significantly more bonding failures occurred in premolar teeth than in anterior teeth.

Comparison of Crime-lite® 82S, Polilight® PL400 and Polilight® PL500 for the detection of semen and saliva stains

ABSTRACT Alternative light sources (ALS) are widely employed in forensic investigations for the identification of biological fluids, such as saliva and semen. While metal halide arc lamps are a common light source for many ALS, high intensity light-emitting diode (LED) globes are a more energy efficient alternative. To date, ALS operating with different light sources have not been evaluated against each other, and this study is the first to complete a side-by-side comparison of the arc lamps, Polilight® PL400 (PL400), Polilight® PL500 (PL500) and the LED-based Crime-lite® 82S (blue) (CL82S) for the detection of semen and saliva dilutions on various fabric materials. The absence or presence of fluorescence were scored independently by four experienced item examination scientists to reduce bias. The number of fluorescence stains detected using the CL82S (244 observations) was higher and brighter in intensity compared to those visualized using PL400 and PL500 (183 and 202 observations, respectively). Notably, dilutions of saliva which were not visible under PL400 and PL500 on a range of fabrics were detected under CL82S, which was statistically significant (p < 0.003). Taken together, CL82S is a better screening tool than the PL400 and PL500 for detection of dilute semen and saliva stains on various fabric types.

Robust Genetic Transformation System to Obtain Non-chimeric Transgenic Chickpea.

Chickpea transformation is an important component for the genetic improvement of this crop, achieved through modern biotechnological approaches. However, recalcitrant tissue cultures and occasional chimerism, encountered during transformation, hinder the efficient generation of transgenic chickpeas. Two key parameters, namely micro-injury and light emitting diode (LED)-based lighting were used to increase transformation efficiency. Early PCR confirmation of positive in vitro transgenic shoots, together with efficient grafting and an extended acclimatization procedure contributed to the rapid generation of transgenic plants. High intensity LED light facilitate chickpea plants to complete their life cycle within 9 weeks thus enabling up to two generations of stable transgenic chickpea lines within 8 months. The method was validated with several genes from different sources, either as single or multi-gene cassettes. Stable transgenic chickpea lines containing GUS (uidA), stress tolerance (AtBAG4 and TlBAG), as well as Fe-biofortification (OsNAS2 and CaNAS2) genes have successfully been produced.

Short communication: Mycosporine-like amino acids protect natamycin against photodegradation in milk exposed to fluorescent or light-emitting diode light

Natamycin has been used as a natural antimicrobial in dairy products, but the poor light stability of natamycin can limit usefulness in food products. Mycosporine-like amino acids are strong UV absorbers and might be useful as an additive to decrease light-induced degradations. Therefore, the objective of this study was to evaluate the photoprotective effect of mycosporine-like amino acids (MAA) in cow milk stored under 2 lighting conditions in retail commercial display cabinets with fluorescent and high intensity light-emitting diode illumination. When milk was exposed to both fluorescent and light-emitting diode light, natamycin degradation was very fast, and only 17.1 ± 0.9% of its original concentration was observed after 8 d at 4.0°C. On the other hand, by adding MAA into milk, natamycin was retained at 82.2 ± 0.9% and 92.2 ± 0.9% when low and high MAA levels were used, respectively. However, high MAA levels resulted in color changes. Therefore, MAA at low levels had a photoprotective effect for natamycin stability in cow milk exposed to light in refrigerated glass containers.

Supplemental But Not Photoperiodic Lighting Increased Seedling Quality and Reduced Production Time of Annual Bedding Plants

In northern latitudes, the photosynthetic daily light integral can be less than 5 mol·m–2·d–1, necessitating the use of supplemental lighting (SL) to reduce bedding plant seedling production time and increase quality. Our objectives were 1) to quantify seedling quality and production time under continuous 16-h or instantaneous threshold SL, continuous low-intensity photoperiodic lighting (PL) for 16 or 24 hours with and without far-red light, or no electric lighting; and 2) to determine whether the described lighting treatments during propagation impact finished plant quality or flowering. Seeds of begonia (Begonia ×semperflorens) ‘Bada Bing Scarlet’, gerbera (Gerbera jamesonii) ‘Jaguar Deep Orange’, impatiens (Impatiens walleriana) ‘Accent Premium Salmon’, petunia (Petunia ×hybrida) ‘Ramblin Peach Glo’, and tuberous begonia (Begonia ×tuberosa) ‘Nonstop Rose Petticoat’ were sown in 128-cell trays and grown under either SL, PL, or no electric lighting (control). SL treatments consisted of high-intensity light-emitting diode (LED) or high-pressure sodium (HPS) lamps providing a photosynthetic photon flux density (PPFD) of either 70 µmol·m–2·s–1 on continuously for 16 h·d–1 or 90 µmol·m–2·s–1 based on an instantaneous threshold. PL treatments consisted of low-intensity red:white (R:W) or red:white:far-red (R:W:FR) lamps for 16 h·d–1 or R:W:FR lamps for 24 h·d–1. Seedlings of gerbera, impatiens, and petunia from each treatment were subsequently transplanted and finished in a common greenhouse environment. The highest quality seedlings were grown under SL compared with PL or control conditions. When comparing SL treatments, seedlings produced under HPS or LED SL using an instantaneous threshold were of equal or greater quality compared with those under continuous SL with a 16-h photoperiod. Although the greater leaf area and internode elongation under PL may give growers the perception that seedling production time is reduced, PL did not increase biomass accumulation and seedling quality. Petunia seedlings propagated under HPS lamps using an instantaneous threshold flowered 4 to 11 days earlier compared with the other SL treatments. In addition, petunia propagated under R:W:FR PL for 16 h·d–1 flowered 5 to 7 days earlier compared with LED SL and the other PL treatments.

Comparison of Supplemental Lighting Provided by High-pressure Sodium Lamps or Light-emitting Diodes for the Propagation and Finishing of Bedding Plants in a Commercial Greenhouse

High-quality young plant production in northern latitudes requires supplemental lighting (SL) to achieve a recommended daily light integral (DLI) of 10 to 12 mol·m−2·d−1. High-pressure sodium (HPS) lamps have been the industry standard for providing SL in greenhouses. However, high-intensity light-emitting diode (LED) fixtures providing blue, white, red, and/or far-red radiation have recently emerged as a possible alternative to HPS lamps for greenhouse SL. Therefore, the objectives of this study were to 1) quantify the morphology and nutrient concentration of common and specialty bedding plant seedlings grown under no SL, or SL from HPS lamps or LED fixtures; and 2) determine whether SL source during propagation or finishing influences finished plant quality or flowering. The experiment was conducted at a commercial greenhouse in West Lafayette, IN. Seeds of New Guinea impatiens (Impatiens hawkeri ‘Divine Blue Pearl’), French marigold (Tagetes patula ‘Bonanza Deep Orange’), gerbera (Gerbera jamesonii ‘Terracotta’), petunia (Petunia ×hybrida ‘Single Dreams White’), ornamental millet (Pennisetum glaucum ‘Jester’), pepper (Capsicum annuum ‘Hot Long Red Thin Cayenne’), and zinnia (Zinnia elegans ‘Zahara Fire’) were sown in 128-cell trays. On germination, trays were placed in a double-poly greenhouse under a 16-hour photoperiod of ambient solar radiation and photoperiodic lighting from compact fluorescent lamps providing a photosynthetic photon flux density (PPFD) of 2 µmol·m−2·s−1 (ambient conditions) or SL from either HPS lamps or LED fixtures providing a PPFD of 70 µmol·m−2·s−1. After propagation, seedlings were transplanted and finished under SL provided by the same HPS lamps or LED fixtures in a separate greenhouse environment. Overall, seedlings produced under SL were of greater quality [larger stem caliper, increased number of nodes, lower leaf area ratio (LAR), and greater dry mass accumulation] than those produced under no SL. However, seedlings produced under HPS or LED SL were comparable in quality. Although nutrient concentrations were greatest under ambient conditions, select macro- and micronutrient concentrations also were greater under HPS compared with LED SL. SL source during propagation and finishing had little effect on flowering and finished plant quality. Although these results indicate little difference in plant quality based on SL source, they further confirm the benefits gained from using SL for bedding plant production. In addition, with both SL sources producing a similar finished product, growers can prioritize other factors related to SL installations such as energy savings, fixture price, and fixture lifespan.