High Light Intensity Research Articles

Unlocking the potential of cacao yield with full sun cultivation

Cacao and chocolate production is a global industry worth around $133 billion. Full sun cultivation is a modern approach aimed at increasing yields. We evaluated six cacao clones (PS 1319, CCN 10, CCN 51, PH 16, SJ 02, and CP 49) grown under full sun conditions to assess their leaf physiology, leaf structure, yield, and yield components. Leaf physiology was measured through seven gas exchange parameters, while leaf structure was analyzed using eight measurements. For fruit and seed, we evaluated seven yield components. The clones showed differences in gas exchange. Clones PH 16 and PS 1319 had higher net photosynthetic rates per unit of leaf area (A), transpiration rates, and lower leaf internal CO2 concentrations. These A high values suggest the clones are well-acclimatized to full sun cultivation. Water availability, nutrient supply, and appropriate plant architecture also contributed to this acclimatization. Under high light intensity, the potential quantum yield of photosystem II indicated no photoinhibition, and adaptations in the photosynthetic apparatus were observed, such as lower pigment concentration in clone PH 16. Clones differed in specific leaf area (SLA) and stomatal density (SD). CCN 51 had a higher SLA, while SJ 02 had a higher SD. A significant negative correlation (-0.89) was found between dry bean yield and leaf-to-air water vapor pressure deficit (VpdL), suggesting that VpdL is a crucial parameter for selecting high-performance clones for fertigated full sun cultivation. Yields ranged from 1,220 kg/ha (CCN 10) to 2,900 kg/ha (CCN 51). Full sun cacao farms have high yield potential due to a combination of cloning, management practices, and adequate water and nutrient availability.

Links Between Two Duckweed Species (Lemna minor L. and Spirodela polyrhiza (L.) Schleid.), Light Intensity, and Organic Matter Removal from the Water—An Experimental Study

Duckweeds—a group of floating leaf macrophytes from the family of Lemnaceae—have become a major area of interest in the fields of basic and applied aquatic sciences in recent decades, including their use in water purification. Aiming to fulfill one of the gaps in the role of light intensity in duckweed efficiency in organic matter removal, we carried out a laboratory experiment with the use of two duckweed species: Lemna minor and Spirodela polyrhiza. Our main finding was that the intensity of light has a positive effect on the process of water purification from organic compounds by Lemna minor. However, this was not applicable to Spirodela polyrhiza due to the fact that the growth of the species was inhibited by high light intensities.

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

Electrophysiological recording of neurons in deep brain regions using optogenetic stimulation is a powerful method for 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 5 × 2 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.

A plant endophytic bacterium Burkholderia seminalis strain 869T2 increases plant growth under salt stress by affecting several phytohormone response pathways

BackgroundDue to global warming and gradual climate change, plants are subjected to a wide range of environmental stresses, adversely affecting plant growth and production worldwide. Plants have developed various mechanisms to overpower these abiotic stresses, including salt stress, drought, and high light intensity. Apart from their own defense strategies, plants can get help from the beneficial endophytic bacteria inside host plants and assist them in enduring severe growth conditions. A previously isolated plant endophytic bacteria, Burkholderia seminalis 869T2, from vetiver grass can produce auxin, synthesize siderophore, and solubilize phosphate. The B. seminalis 869T2 can colonize inside host plants and increase the growth of bananas, Arabidopsis, and several leafy vegetables.ResultsWe further demonstrated that different growth parameters of Arabidopsis and pak choi plants were significantly increased after inoculating the B. seminalis 869T2 under normal, salt, and drought stress conditions compared to the mock-inoculated plants. Both transcriptome analysis and quantitative real-time PCR results showed that expression levels of genes related to phytohormone signal transduction pathways, including auxin, gibberellin, cytokinin, and abscisic acid were altered in Arabidopsis plants after inoculated with the strain 869T2 under salt stress, in comparison to the mock-inoculated control with salt treatments. Furthermore, the accumulation levels of hydrogen peroxide (H2O2), electrolyte leakage (EL), and malondialdehyde (MDA) were lower in the 869T2-inoculated Arabidopsis and pak choi plants than in control plants under salt and drought stresses.ConclusionsThe plant endophytic bacterium strain B. seminalis 869T2 may affect various phytohormone responses and reduce oxidative stress damage to increase salt and drought stress tolerances of host plants.

Raman signal enhancement via a micro-ring resonator

This study presents the use of micro-ring resonator (MRR) devices to extract and enhance nonlinear signals. MRRs “trap” incoming light and, therefore, have been shown to achieve extremely high local intensities of light. Thus, they can be used to facilitate highly nonlinear optical signals that are usually weak in intensity and require high excitation power. By embedding materials that host nonlinear optical processes inside the MRR, we expect to observe an enhancement in the strength of the nonlinear optical signals. This concept is demonstrated here by extracting the Raman signature of graphene that is placed inside a MRR device. A highly doped silica MRR featuring an optical bus waveguide coupled to a ring tuned to near-infrared wavelengths is used. Raman signal with an excitation wavelength of 522 nm via third-harmonic generation inside the MRR is observed. The higher-order Raman signal of the embedded graphene is also observed at the 1597.6 nm excitation wavelength. This work demonstrates the feasibility of the MRR as a nonlinear signal enhancer using high-Q MRR device setups.

Uncovering the Origin of Light‐Promoted Synergetic Effect and Y Doping in Enhancing Photothermocatalytic Dry Reforming of Methane on Ni/Ni‐Y2‐Al2O3

Photothermocatalytic dry reforming of methane (DRM) can convert CH4 and CO2 into syngas, offering an effective approach to reducing greenhouse gas emissions. However, photothermocatalytic DRM reaction generally needs a high light intensity surpassing 192 kW m−2 to attain high light‐fuel conversion. Also, catalysts applied to photothermocatalytic DRM are liable to inactivation due to carbon deposition. Herein, a nanocomposite of Ni nanoparticles supported on Ni‐ and Y‐doped Al2O3 (Ni/Ni‐Y2‐Al2O3) is prepared. It achieves high H2 and CO production rates with a light‐to‐fuel efficiency (29.2%) at a lower intensity (80.1 kW m−2). Meanwhile, it sustains excellent photothermocatalytic durability and accomplishes a 37‐fold reduction in carbon deposition rate compared to Ni/Al2O3. The substantially enhanced catalytic activity and carbon resistance of Ni/Ni‐Y2‐Al2O3 are correlated with accelerating carbon species (C*) oxidation (the rate‐determining steps of DRM). This acceleration derives from the synergetic effect and carbonate species resulting from Y doping, which participate in C* oxidation via two separate reaction pathways. When in light, the synergetic effect further facilitates C* oxidation. Simultaneously, light immensely reduces activation energy, activates the NiO bonds at the interface region, and expedites the reaction between carbonate species and C* in the interface, enhancing catalytic activity and carbon resistance.

Comparison of the Effect of High Light Intensity on the Response of Solanum lycopersicum and Arabidopsis thaliana to Low Temperature

This study compares the effect of light intensity on the responses of two plants with different cold tolerance – tomato (Solanum lycopersicum L.) and on model plant Arabidopsis (Arabidopsis thaliana Col 0) to several days' treatment by low temperature and after recovery at control conditions. Net photosynthetic rate was evaluated by oxygen evolution from leaf discs. The photosynthetic performance was assessed by the maximal quantum efficiency of photosystem II and the degree of non-photochemical and non-regulated quenching. Malondialdehyde accumulation was used as a stress indicator and synthesis and accumulation of anthocyanins as an indicator for activation of defense mechanism. The results demonstrated that in Arabidopsis plants the high light treatment at control and low temperature increased non-regulated quenching but, in tomato plants the balance between both quenching mechanisms was maintained.

A Spiropyran-Based Hydrogel Composite for Wearable Detectors to Monitor Visible Light Intensity to Prevent Myopia.

A wearable detector to monitor visible light intensity is realized by the restrained photochromism of a hydrogel composite containing light-responsive spiropyran with hydroxyl groups (SPOH). When exposed to visible light, the SPOH experiences a ring-opening to a ring-closed transition accompanied by discoloration from red to yellow. Unlike in the solution, the photochromism/discoloration rate is strongly correlated to the cross-linking points. By reducing the amount of cross-linker from 40 to 5 mg, the photochromism rate of SPOH is 300% faster. Inspired by the Chinese Jade Loong from Hongshan, the hydrogel composite is shaped into a Loong to monitor the light intensity. By increasing the amount of cross-linker in the head, body, and tail, the photochromism/discoloration rate sequentially turns slower from one region to the other. Higher light intensity is required to realize the discoloration in the hydrogel composite containing a larger amount of the cross-linker. Because the initial colors are identical, the light intensity can be easily traced by checking the discoloration of these pieces containing different amounts of cross-linker. Based on this unique and reversible photochromic capability, the present hydrogel composite can be used for monitoring the visible light intensity to prevent myopia, especially for children and students.

Metabolic activity controls the emergence of coherent flows in microbial suspensions

Photosynthetic microbes have evolved and successfully adapted to the ever-changing environmental conditions in complex microhabitats throughout almost all ecosystems on Earth. In the absence of light, they can sustain their biological functionalities through aerobic respiration, and even in anoxic conditions through anaerobic metabolic activity. For a suspension of photosynthetic microbes in an anaerobic environment, individual cellular motility is directly controlled by its photosynthetic activity, i.e. the intensity of the incident light absorbed by chlorophyll. The effects of the metabolic activity on the collective motility on the population level, however, remain elusive so far. Here, we demonstrate that at high light intensities, a suspension of photosynthetically active microbes exhibits a stable reverse sedimentation profile of the cell density due to the microbes' natural bias to move against gravity. With decreasing photosynthetic activity, and therefore suppressed individual motility, the living suspension becomes unstable giving rise to coherent bioconvective flows. The collective motility is fully reversible and manifests as regular, three-dimensional plume structures, in which flow rates and cell distributions are directly controlled via the light intensity. The coherent flows emerge in the highly unfavorable condition of lacking both light and oxygen and, thus, might help the microbial collective to expand the exploration of their natural habitat in search for better survival conditions.

Light quality affects chlorophyll biosynthesis and photosynthetic performance in Antarctic Chlamydomonas.

The perennially ice-covered Lake Bonney in Antarctica has been deemed a natural laboratory for studying life at the extreme. Photosynthetic algae dominate the lake food webs and are adapted to a multitude of extreme conditions including perpetual shading even at the height of the austral summer. Here we examine how the unique light environment in Lake Bonney influences the physiology of two Chlamydomonas species. Chlamydomonas priscui is found exclusively in the deep photic zone where it receives very low light levels biased in the blue part of the spectrum (400-500nm). In contrast, Chlamydomonas sp. ICE-MDV is represented at various depths within the water column (including the bright surface waters), and it receives a broad range of light levels and spectral wavelengths. The psychrophilic character of both species makes them an ideal system to study the effects of light quality and quantity on chlorophyll biosynthesis and photosynthetic performance in extreme conditions. We show that the shade-adapted C. priscui exhibits a decreased ability to accumulate chlorophyll and severe photoinhibition when grown under red light compared to blue light. These effects are particularly pronounced under red light of higher intensity, suggesting a loss of capability to acclimate to varied light conditions. In contrast, ICE-MDV has retained the ability to synthesize chlorophyll and maintain photosynthetic efficiency under a broader range of light conditions. Our findings provide insights into the mechanisms of photosynthesis under extreme conditions and have implications on algal survival in changing conditions of Antarctic ice-covered lakes.

The resistance of Solanum lycopersicum photosynthetic apparatus to high-intensity blue light is determined mainly by the cryptochrome 1 content

The resistance of Solanum lycopersicum photosynthetic apparatus to high-intensity blue light is determined mainly by the cryptochrome 1 content

Scaling Up Gas–Liquid Photo-Oxidations in Flow Using Rotor-Stator Spinning Disc Reactors and a High-Intensity Light Source

Scaling Up Gas–Liquid Photo-Oxidations in Flow Using Rotor-Stator Spinning Disc Reactors and a High-Intensity Light Source

Effects of Light Intensity and Irrigation Method on Growth, Quality, and Anthocyanin Content of Red Oak Lettuce (Lactuca sativa var. cripspa L.) Cultivated in a Plant Factory with Artificial Lighting

Cultivating red oak lettuce in plant factories often encounters challenges in achieving the desired red leaf coloration. To make the leaves a pleasant red color, anthocyanins are key substances that need to be induced. This study aimed to evaluate the effects of increasing light intensity and irrigation methods on the growth and leaf color of red oak lettuce in a controlled environment. Two light intensities (300 and 400 µmol m−2 s−1) with white LEDs and two irrigation methods (circulating vs. non-circulating irrigation) were applied seven days before harvesting. The results indicated that plants grown with circulating irrigation exhibited significantly higher fresh and dry weights than those grown under non-circulating conditions, regardless of light intensity. When non-circulating irrigation was applied, shoot fresh weight decreased by approximately 22% on the harvesting day compared to the circulating treatments. Under the 400 µmol m−2 s−1 light intensity with non-circulating irrigation (400N-C), plants displayed the lowest lightness (L*) at 40.7, increased redness (a*) to −7.4, and reduced yellowness (b*) to 11.0. These changes in coloration were optimized by day 5 after treatment. Additionally, spectral indices, including normalized difference vegetation index and photochemical reflectance index, varied significantly among treatments. The 400N-C treatment also resulted in the highest anthocyanin content and antioxidant activity in red oak lettuce. These findings suggest that combining high light intensity with non-circulating irrigation before harvest can improve both the coloration and quality of red oak lettuce in plant factories with artificial lighting.

Cobalt tungstate nanoparticles (CoWO4 NPs) affect the photosynthetic performance of the green microalga Raphidocelis subcapitata.

Innovative applications of cobalt tungstate nanoparticles (CoWO4 NPs) are directly linked to their increased production and consumption, which can consequently increase their release into aquatic ecosystems and the exposure of organisms. Microalgae are autotrophic organisms that contribute directly to global primary productivity and provide oxygen for maintaining many organisms on Earth. In this paper, we assessed the toxicity of CoWO4 NPs when in contact with the freshwater microalga Raphidocelis subcapitata (Chlorophyceae). To this end, we assessed algal growth, reactive oxygen species (ROS) production and photosynthetic performance. Our results show that the NPs inhibited the growth of algal cells from 42.37 mg L-1, significantly induced ROS production in the first hours of exposure (1 h) at all concentrations and directly compromised the photosynthetic activity, reinforcing that the oxygen-evolving complex (OEC) is one of the main targets of NPs and that the light curve parameters were the most sensitive endpoints. We observed reductions in the maximum relative electron transport rate (rETRmax) of around 53% and decreases in the saturating irradiance (Ek) of around 40%, which demonstrated that the NPs not only compromised the photosynthetic activity, but also decreased the ability of algal cells to tolerate high light intensities. Our results also highlight that Co was mostly particulate and that the dissolved fraction represented only ∼8% at the lowest concentration and ∼ 0.70% at the highest concentration of CoWO4 NPs, suggesting that the toxicity observed was caused by the NPs. CoWO4 NPs exhibited a high negative surface charge of -33mV in L.C. Oligo medium. The polydispersity index (PdI) varied from 0.22 to 0.45, while the hydrodynamic size ranged from 217.8 ± 11.36 to 503.43 ± 32.78 nm, indicating greater aggregation in this medium. This study elucidates how the CoWO4 NPs interact with R. subcapitata¸ resulting in changes mainly in its photosynthetic performance.

The effects of nickel tungstate nanoparticles (NiWO4 NPs) on freshwater microalga Raphidocelis subcapitata (Chlorophyceae).

Among the vast array of functional nanoparticles (NPs) under development, nickel tungstate (NiWO4) has gained prominence due to its potential applications as a catalyst, sensor, and in the development of supercapacitors. Consequently, new studies on the environmental impact of this material must be conducted to establish a regulatory framework for its management. This work aims to assess the effects of NiWO4 (NPs) on multiple endpoints (e.g., growth, photosynthetic activity, and morphological and biochemical levels) of the freshwater microalga Raphidocelis subcapitata (Chlorophyceae). Quantification data revealed that the fraction of dissolved Ni and free Ni2+ increased proportionally with NiWO4 NP concentrations, although these levels remained relatively low. Biological results indicated that NiWO4 NPs did not inhibit the growth of algal cells, except at 7.9mg L-1, resulting in a 9% decrease. Morphological changes were observed in cell size and complexity, accompanied by physiological alterations, such as a reduction in chlorophyll a fluorescence (FL3-H) and signs of impaired photosynthetic activity, indicated by the effective quantum yield, quenchings, and chlorophyll a (Chl a) content. Furthermore, the rapid light curves showed that the NPs in high concentrations affected microalga ability to tolerate high light intensities, as corroborated by the significant decrease in the relative electron transport rate (rETRmax) and saturation irradiance (Ek). Based on the present study results, we emphasize the importance of applying integrative approaches in ecotoxicological studies, since each endpoint evaluated showed different sensitivity.

Effect of daytime light intensity on daily behaviours and concurrent hypothalamic gene expressions in migratory redheaded bunting.

Animals use photic cues to time their daily and seasonal activity. The role of photoperiod has been much investigated in seasonal responses, but the role of light intensity is less understood in passerine finches. We investigated if and how daytime light intensity influences photoinduced migratory phenologies and hypothalamic mRNA expressions in a Palearctic-Indian migratory finch, redheaded bunting (Emberiza bruniceps). Photoperiodic manipulations were employed to induce winter-nonmigratory (NM), premigratory (PM), and migratory (MIG) states in photosensitive buntings. In each life history state, the birds were further subjected to 0.055 (low), 0.277 (medium), or 1.11W/m2 (high) (N =5 each) light intensity treatment. The low daytime light intensity dampened the locomotor activity rhythm and delayed the onset of Zugunruhe. We found life history-dependant but not light intensity-dependant changes in body mass, fat score, and testis volume. Plasma corticosterone levels were increased under the low-light intensity group in the migratory state. The buntings were foraging throughout the night in the migratory state, aiding body fattening. Front and back sleep were drastically reduced during the migratory phase under all three light intensities. In the migratory state, we found elevated hypothalamic IL1B and IL6 expression in medium and high-light intensity groups, which had significantly reduced sleep duration. In the winter nonmigratory state, the expression of CAMK2 correlated with daytime activity and active wakefulness of buntings. The decreased GHRH expression correlates with the reduction in total sleep in migrating buntings. Overall, daytime light intensity emerges as a key factor that fine-tunes the photoperiodic response and regulates active and sleep behaviour in migratory buntings.

Effects of light intensity on the antioxidant activity, ATPases, and digestive enzymes of crimson snapper (Lutjanus erythropterus) juveniles during long-hour road transport.

The transportation of fish larvae or juveniles from hatcheries to rearing farms is a crucial process in aquaculture, as most fish farms are located far from hatcheries. Among abiotic parameters, light intensity is an important factor affecting the physiology and biochemistry of teleost fish. To date, most studies on fish transportation have focused on identifying the optimum stocking density, while little is known about the optimum light intensity for transporting hatchery-produced juvenile Crimson snapper (Lutjanus erythropterus). Therefore, this study aimed to evaluate the effects of light intensity on antioxidative stress, digestive enzymes, and ATPases in Lutjanus erythropterus during long-hour transportation. The results of this study revealed that a light intensity between 100 and 500 Lux is recommended for the long-hour transport of L. erythropterus juveniles. Complete darkness increased the concentration of ammonia in the water by about 15 % and induced oxidative stress, whereas high light intensities reduced dissolved oxygen levels (up to 6 %) and pH (up to 6 %), increased water temperature (about 10 %), and caused significant oxidative stress in the fish. It is also worth noting that α-amylase activity increased significantly, while ATPase activity decreased significantly under both complete darkness (α-amylase activity = +40 %; ATPase activity = up to -130 %) and high light intensities (α-amylase activity = +21-52 %; ATPase activity = up to -43 %). The findings of this study can provide a guideline for improving current transportation techniques, thereby minimizing stress on L. erythropterus in a cost effective manner.

Optimize the preparation process of m-TiO2@CdS by response surface methodology to enhance the light intensity adaptability of photocatalytic degradation of tetracycline

Catalyst performance is traditionally evaluated under high light intensity, where variations in e--h+ pair recombination rates at different light intensities may limit the applicability of the selected catalyst to diverse light sources. Response surface methodology (RSM) was employed to compare catalyst performance under two optimization processes, using tetracycline degradation rate and photon flux as response variables. The m-TiO2@CdS catalyst was characterized by XRD, SEM, TEM, XPS, and UV-Vis-DRS, and its preparation process was optimized using RSM, with precursor ratio, hydrothermal time, and temperature as variables. The proposed optimization model for tetracycline degradation rate and photon flux exhibited a strong correlation between predicted and experimental results. The tetracycline degradation rates for the two optimized preparation processes were nearly identical, at 61.87% and 61.18%, respectively. A comparison of tetracycline degradation kinetics under different light conditions (light saturation and non-saturation) for the two optimized m-TiO2@CdS samples demonstrated that the photon flux-based optimization model offered greater adaptability across a wider range of light intensities. Additionally, the repeatability of m-TiO2@CdS prepared under the optimal conditions was assessed, and a plausible mechanism for its photocatalytic degradation of tetracycline was proposed.

Core-shell structured BN/SiO2 nanofiber membrane featuring with dual-effect thermal management and flame retardancy for extreme space thermal protection.

With the rapid progress of aerospace frontier engineering, the extreme space thermal environment has brought severe challenges to astronauts' space suits, putting forward higher requirements for thermal protection materials. On this basis, a unique core-shell structured hexagonal boron nitride (h-BN)/silicon dioxide (SiO2) nanofiber membrane (HS) was prepared using the coaxial electrospinning method, of which both the thermal insulation SiO2 nanofiber cortex and the passive radiation cooling (PRC) h-BN nanofiber core make it a promising dual-effect thermal management material. Especially, when the amount of h-BN is 0.9g, the resultant HS (HS0.9) exhibits astonishing low thermal conductivity of 0.026Wm-1K-1 and high reflectivity and emissivity of exceeding 90% over an extremely wide range. The expected dual-effect thermal management performance enables the HS to have an ideal cooling effect under both high sunlight intensity and strong light radiation. In addition, HS also shows excellent flame retardant performance arising from the excellent high-temperature stability of h-BN and SiO2. What is more, the tensile strength of HS0.9 was also significantly increased from 0.42 to 7.2MPa by encapsulating polyimide through vacuum filtration. Therefore, the research results of this work provide innovative highlights for high-temperature protection in daily life and even extreme space environments.

The interplay of irradiated- and shaded zones in photoreactor scale-up

Photochemical processes enable highly-selective synthesis routes under mild reaction conditions. Yet, photoreactions are seldom implemented on industrial scale. One of the main challenges is the exponential light attenuation with increasing optical depth. As a result, few photons are available at positions far from the light source, leading to shaded zones of low reactivity. To study the effect of shaded zones, a compartment photoreactor model is presented and used for optimization of the reaction conditions, in particular during scale-up. Using photooxidation in a Taylor-flow capillary reactor as a benchmark case, the photosensitizer concentration, the light intensity and liquid mixing are identified as the key parameters for the formation and impact of shaded zones on reactor performance. It is shown that shading reduces the conversion already on lab-scale by up to 13% for operating conditions with high photosensitizer concentration and light intensity. In an upscaled reactor, intensified liquid mixing leads to an up to 4.3-fold increase in conversion