Increase In Light Intensity Research Articles

Distinct responses of diatom- and flagellate-dominated Antarctic phytoplankton communities to altered iron and light supply

Primary production in the Southern Ocean is strongly influenced by the availability of light and iron (Fe). To examine the response of two distinct natural Antarctic phytoplankton communities (diatom vs. flagellates) to increasing light and Fe availability, we conducted two shipboard incubation experiments during late summer and exposed each community to increasing light intensities (30, 80, and 150 µmol photons m−2 s−1) with or without Fe amendment. Our results show clearly that both communities were Fe-limited since Fe addition resulted in higher particulate organic carbon (POC) production rates. The magnitude of the Fe-dependent increase in POC production, however, varied between the two stations being higher in the diatom-dominated community relative to the flagellate-dominated community. This differential response to increasing Fe supply could be attributed to the higher Fe requirement of the flagellate-dominated assemblage relative to the diatom-dominated assemblage. Irrespective of Fe availability, light also strongly stimulated the POC production of both communities between low and medium light supply (30 versus 80 µmol photons m−2 s−1), indicating that both assemblages were light-limited in situ. However, since POC production of both communities did not increase further at the highest light intensity (150 µmol photons m−2 s−1) even under high Fe supply, this suggests that light supply was saturated or that other conditions must be fulfilled (e.g., availability of trace metals other than Fe) in order for the communities to benefit from the higher light and Fe conditions.

An Antagonistic Photovoltaic Memristor for Bioinspired Active Contrast Adaptation.

Machine vision systems that consist of cameras and image-processing components for visual inspection and identification tasks play a critical role in various intelligent applications, including pilotless vehicles and surveillance systems. However, current systems usually possess a limited dynamic range and fixed photoresponsivity, restricting their capability of gaining high-fidelity images when encoding a high-contrast scene. Here, it is shown that a photovoltaic memristor incorporating two antagonistic photovoltaic junctions can autonomously adjust its response to varying light stimuli, enabling the amplification of shadows and inhibition of highlight saturation. Due to the dynamic photodoping effect at the p-n junction with an asymmetrical profile, the photocurrent polarities of the antagonistic memristor can be changed as the light intensity increases. The light-intensity-dependent switchable photovoltaic behaviors match Weber's law where photosensitivity is inversely proportional to the light stimuli. An 11×11 memristor array is used to detect a high-contrast scene with light intensities ranging from 1 to 5×104 µW cm-2, achieving a similar active contrast adaptation performance compared with the human visual systems (less than 1.2 s at 94 dB). This work paves the way for innovative neuromorphic device designs and may lead to the development of state-of-the-art active visual adaptation photosensors.

Varying levels of natural light intensity affect the phyto-biochemical compounds, antioxidant indices and genes involved in the monoterpene biosynthetic pathway of Origanum majorana L.

BackgroundLight is a critical environmental factor in plants, encompassing two vital aspects: intensity and quality. To assess the influence of different light intensities on Origanum majorana L., pots containing the herb were subjected to four levels of light intensity: 20, 50, 70, and 100% natural light. After a 60-day treatment period, the plants were evaluated for metabolite production, including total sugar content, protein, dry weight, antioxidant indices, expression of monoterpenes biosynthesis genes, and essential oil compounds. The experimental design followed a randomized complete blocks format, and statistical analysis of variance was conducted.ResultsThe results indicated a correlation between increased light intensity and elevated total sugar and protein content, which contributed to improved plant dry weight. The highest levels of hydrogen peroxide and malondialdehyde (MDA) were observed under 100% light intensity. Catalase and superoxide dismutase enzymes exhibited increased activity, with a 4.23-fold and 2.14-fold increase, respectively, under full light. In contrast, peroxidase and polyphenol oxidase enzyme activities decreased by 3.29-fold and 3.24-fold, respectively. As light intensity increases, the expression level of the 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) gene increases. However, beyond a light intensity of 70%, the DXR gene expression level decreased. Furthermore, the expression levels of the cytochrome P450 genes CYP71D178 and CYP71D179 exhibited an increasing trend in response to elevated light intensity. Essential oil content increased from 0.02 to 0.5% until reaching 70% light intensity. However, with further increases in light intensity, the essential oil content decreased by 54 to 0.23%.ConclusionsThese findings emphasize the importance of balancing plant growth promotion and stress management under different light conditions. The research suggests that sweet marjoram plants thrive best in unshaded open spaces, resulting in maximum biomass. However, essential oil production decreases under the same conditions. For farmers in areas with an average light intensity of approximately 1700 µmol m−2s−1, it is recommended to cultivate sweet marjoram in shade-free fields to optimize biomass and essential oil production. Towards the end of the growth cycle, it is advisable to use shades that allow 70% of light to pass through. The specific duration of shade implementation can be further explored in future research.

Sinusoidal LED light recipes can improve rocket edible biomass and reduce electricity costs in indoor growth environments.

Accumulation of edible biomass by crop plants relies on maintenance of a high photosynthetic rates across the photoperiod, with assimilation rate (A) generally responding to increasing light intensity in a hyperbolic fashion. In natural environments light fluctuates greatly over the course of the day, however in Controlled Environmental Agricultural (CEA) systems, light intensity can be supplemented or precisely controlled using LEDs to create near optimum conditions. In such indoor growth environments light is often delivered as a square wave and recommendations to horticulturalists are given in the form of Daily Light Integrals (DLI). However, this does not take into account the slow photosynthetic induction at the start of the photoperiod and the decline of A towards the end of the photoperiod, which has been demonstrated by several previous studies. Square wave light regimes therefore potentially cause suboptimal photosynthetic utilization of the applied lighting and waste electricity. Here we have adapted light recipes to gradually increase and decrease in intensity to take account of these findings. We demonstrate that, utilising a sinusoidal light regime capped at 250 μmol m-2 s-1, it is possible to increase edible biomass of rocket (by ca. 20%) compared to square wave delivered at 250 at the same DLI. Additionally, this can be achieved using less electricity (0.6%), therefore reducing energy costs and improving profitability. We suggest that capping maximum light intensity at 250 µmol m-2 s-1 improves the operating efficiency of PSII photochemistry (Fq'/Fm') also known as the photosynthetic efficiency by maintaining A later in the photoperiod. We show that a higher electron transfer rate (ETR) is maintained in these treatments over the photoperiod compared to higher light intensity caps, resulting in a greater Daily Photochemical Integral (DPI). We attribute this to less NPQ due to a greater sink capacity for the end products of electron transport, ATP and NADPH, as A is kept high for longer.

Metabolomics of related C3 and C4 Flaveria species indicate differences in the operation of photorespiration under fluctuating light.

C3 photosynthesis can be complemented with a C4 carbon concentrating mechanism (CCM) to minimize photorespiratory losses. C4 photosynthesis is often more efficient than C3 under steady-state conditions. However, the C4 CCM depends on inter-cellular metabolite concentration gradients, which must increase following increases in light intensity and could decrease rates of C4 photosynthesis under fluctuating light. Additionally, incomplete flux through photorespiration could prove beneficial to C4 assimilation during light induction of the CCM. Here, we compare metabolic profiles in the closely related C3 Flaveria robusta and C4 Flaveria bidentis during a light transient from low to high light to determine if these non-steady state accumulation patterns provide insight to the induction of the metabolite gradients needed to drive C4 intermediate transport and if there is incomplete cycling of photorespiratory intermediates. In these C3 and C4 species, metabolite steady-state pool sizes suggest that C4 transport acids maintain concentration gradients across the bundle sheath and mesophyll cell types under these light fluctuations. However, there was incomplete flux through photorespiration in the C4 F. bidentis, which could reduce photorespiratory CO2 loss via glycine decarboxylation and help maintain higher rates of assimilation during following induction periods.

Influence of light intensity on the responses of seedlings of neotropical tree species to nitrogen source

Light intensity plays a crucial role in N uptake and assimilation in plants, but its interaction with different N sources is overlooked. Considering the high energy required for N assimilation, it is hypothesised that low light is critical for the seedling development with both N sources, but with increased light intensity, growing with nitrate (NO3-) becomes favourable in relation to ammonium (NH4+). Seedlings of Cecropia pachystachya (pioneer), Guarea kunthiana (shade-tolerant, understory) and Cariniana estrellensis (shade-tolerant, canopy) were grown in hydroponic medium with NO3- or NH4+ as the sole N source and subjected to low (LL) or high light (HL) for 60 days. All three species showed a decrease in growth when cultivated with NH4+, compared to NO3-, under HL, but not under LL. The decrease in biomass reached 54% in C. pachystachya, 36% in G. kunthiana and 26% in C. estrellensis. Growth reduction was associated with stomatal limitation of photosynthesis and reduced leaf area in C. pachystachya, and with non-stomatal limitation of photosynthesis and oxidative stress in G. kunthiana. Cation uptake was negatively affected by NH4+ in all species. Cariniana estrellensis showed no photosynthetic limitation and showed a higher tolerance to NH4+ under HL in terms of nutrient content. In conclusion, neither N source significantly favors seedling development under LL, while NH4+ is considerably more unfavorable for seedling development than NO3- under HL.

Effects of Different Shade Treatments on the Epidermal Wax Deposition of Hosta Genotypes with Different Glaucousness of Leaf Surface

Epidermal wax is strategically situated at the interface between plants and air; therefore, it plays a key role in plants’ interactions with their surroundings. It is also unstable and susceptible to light intensity. Hosta plants are shade-loving herbs with admirable flowers and leaves. Hosta ‘Halcyon’ and Hosta ensata F. Maek. are two species of Hosta with a glaucous and a glossy appearance, respectively. Light intensity can affect the composition of epicuticular wax on the leaf surface, which influences the leaf color phenotype and ornamental value. In this paper, the crystal micromorphology, content, and components of epicuticular wax on the leaves of two species of Hosta under different light conditions (10%-, 30%-, 50%-, 70%-, and 100%-intensity sunlight, relative light intensity (RLI)) have been studied using pot experiments. The results indicate that the epicuticular wax crystals of H. ‘Halcyon’ and H. ensata are tubular and platelet-like, respectively. The wax crystals of H. ‘Halcyon’ melted and formed a thick crust under 100% RLI, and those of H. ensata melted and formed a thick crust under 70% and 100% RLI conditions. The primary ingredients of the epicuticular wax of the two species of Hosta contained primary alcohols, alkanes, fatty acids, and esters; β-diketones were only detected in H. ‘Halcyon’. The quantity of epicuticular wax of H. ‘Halcyon’ reduced at first and then increased with an RLI increase, achieving its lowest value at 50% RLI, but that of H. ensata declined little by little. The amounts of C28 primary alcohols, C31 alkanes, and C18 fatty acids were significantly higher than those of other carbon atoms in the two genotypes of Hosta. The C31β-diketones content decreased with the increase in light intensity, which caused the white frost phenotype to gradually weaken in H. ‘Halcyon’.

Comparative transcriptome analysis reveals molecular mechanisms of the effects of light intensity and photoperiod on ovarian development in Procambarus clarkii (Girard, 1852)

Procambarus clarkii (Girard, 1852) has important economic value in China and internationally. In this research, the comparative transcriptome analysis was used to reveal molecular mechanisms of influences of photoperiod and light intensity on ovarian development in P. clarkii for the first time. Some genes (such as laminin, collagen, integrin beta, catenin) and pathways (including TGF-beta signaling pathway, focal adhesion, ECM–receptor interaction) associated with ovarian development and oocyte maturation were significantly upregulated. Some genes related to circadian clock (such as CLK, PER) were identified in this research. The results indicated that when light intensity or photoperiod increased, P. clarkii could up-regulate the expression levels of the laminin and collagen, thereby synthesizing related proteins, promoting meiosis of the oocytes, thus increasing the number of oocytes in the ovary. At the same time, P. clarkii could up-regulate the expression levels of integrin beta, integrin alpha 6, and diacylglycerol to synthesize related proteins, thereby promoting the formation of proteins and fats such as triglycerides, these proteins and fats can provide material basis for maturation and development of oocytes, resulting in oocyte maturation and ovarian development. P. clarkii could synthesize related proteins by upregulating expression levels of genes (such as catenin), these proteins or hormones can adhere to other actins (such as integrins), thereby stabilizing the morphology of the oocytes and ensuring normal development. Meantime, the increase in light intensity or photoperiod could cause release GSH and VTG, resulting in oocytes development and maturation. The data in this research can reveal molecular mechanisms of impacts of photoperiod and light intensity on oocyte maturation and ovarian development in P. clarkii, can offer crucial genomic data for studying developmental mechanisms of ovary and oocyte in crustacean.

Experimental Analysis of IPMC Optical-Controlled Flexible Driving Performance under PLZT Ceramic Configuration.

Ionic polymer metal composite (IPMC) is regarded as the mainstream application material for achieving flexible driving technology in various engineering fields. In this article, aiming at the non-independence of the current IPMC electric driving method, an IPMC optical-controlled flexible driving method based on the photoinduced effects of lanthanum-modified lead zirconate titanate (PLZT) ceramic is proposed. To this end, a mathematical model for IPMC optical controlled flexible driving is built on the basis of the photovoltaic characteristic of PLZT ceramic, and the driving performance is experimentally analyzed through different lengths of IPMC under the excitation of different direct currents and light intensities. From the analysis and experimental results, when PLZT ceramic is irradiated by different light intensities, the output deformation of IPMC increases with increases in light intensity, and finally reaches a stable state. Moreover, the actuation curves obtained by light excitation and direct current excitation are consistent, and the motion coefficient reflects the driving performance more accurately. In addition, using light energy as an excitation source to drive IPMC not only provides new ideas for its development in the flexible driving field, but also provides a theoretical basis for its practical application.

Endophyte-assisted non-host plant Tillandsia brachycaulos enhance indoor formaldehyde removal

This study investigated the use of endophyte-assisted Tillandsia brachycaulos to enhance formaldehyde removal in indoor environments. A formaldehyde-degrading endophyte from the root of Epipremnum aureum, Pseudomonas plecoglossicida, was identified and used for inoculation. Among the inoculation methods, spraying proved to be the most effective, resulting in a significant 35 % increase in formaldehyde removal after 36 hours. The results of the light exposure experiment (3000 Lux) demonstrate that an increase in light intensity reduces the efficiency of the Tillandsia brachycaulos-microbial system in degrading formaldehyde. In a 15-day formaldehyde fumigation experiment at 2 ppm in a normal indoor environment, the inoculated Tillandsia brachycaulos exhibited removal efficiency ranging from 42.53 % to 66.13 %, while the uninoculated declined from 31.62 % to 3.17 %. The Pseudomonas plecoglossicida (referred to as PP-1) became the predominant bacteria within the Tillandsia brachycaulos after fumigation. Moreover, the endophytic inoculation effectively increased the resistance and tolerance of Tillandsia brachycaulos to formaldehyde, as evidenced by lower levels of hydroxyl radical, malondialdehyde (MDA), free protein, and peroxidase activity (POD), as well as higher chlorophyll content compared to uninoculated Tillandsia brachycaulos. These findings indicate that the combination of endophytic bacteria and Tillandsia brachycaulos has significant potential for improving indoor air quality.

A practical approach for extracting the photosystem II (PSII) contribution to near-infrared solar-induced chlorophyll fluorescence

Recent studies have indicated a good potential for using solar-induced chlorophyll fluorescence (SIF) to estimate photosynthetic CO2 assimilation. SIF can be emitted by both Photosystem I (PSI) and Photosystem II (PSII), but it is the SIF signals from PSII which are related to photosynthetic carbon fixation. However, since top-of-canopy SIF observations (SIFTOC) always contain contributions from both photosystems, to mechanistically estimate gross primary productivity (GPP) from SIF, it is essential to extract PSII SIF from SIFTOC. Based on the differences in the relative contribution of PSII across different wavelengths, we propose a practical approach for extracting PSII contribution to SIFTOC at the near-infrared (NIR) band (fPSII_760) using measurements of SIFTOC in the red and NIR spectral regions. A leaf-scale concurrent instrument was developed to assess the response of fPSII_760 under varying environments. For winter-wheat leaves, as light intensity increased from 0 to 400 μmol m−2 s−1, fPSII_760 rose from 0.6 to 0.8; with further increase in light intensity to 1800 μmol m−2 s−1, fPSII_760 consistently decreased to 0.65. There was a slight decreasing trend in fPSII_760 with rising temperatures, with values dropping from 0.65 at 15 °C to 0.61 at 40 °C. We found that variations in fPSII_760 are due to changes in the fluorescence yield of PSII, with the two having a positively proportional relationship. We also estimated canopy-scale fPSII_760 for a winter-wheat study site: fPSII_760 varied from 0.61 to 0.83, with a mean value of 0.78 during the peak growing season. A comparison with eddy covariance-derived GPP reveals that GPP estimated with dynamic fPSII_760 was more accurate than that calculated using fixed fPSII_760, with R2 increasing from 0.6 to 0.84. This study contributes to a deeper understanding of the link between SIF and photosynthetic CO2 assimilation, paving the way for more effective use of SIF to estimate GPP.

The Light-Fueled Self-Rotation of a Liquid Crystal Elastomer Fiber-Propelled Slider on a Circular Track.

The self-excited oscillation system, owing to its capability of harvesting environmental energy, exhibits immense potential in diverse fields, such as micromachines, biomedicine, communications, and construction, with its adaptability, efficiency, and sustainability being highly regarded. Despite the current interest in track sliders in self-vibrating systems, LCE fiber-propelled track sliders face significant limitations in two-dime nsional movement, especially self-rotation, necessitating the development of more flexible and mobile designs. In this paper, we design a spatial slider system which ensures the self-rotation of the slider propelled by a light-fueled LCE fiber on a rigid circular track. A nonlinear dynamic model is introduced to analyze the system's dynamic behaviors. The numerical simulations reveal a smooth transition from the static to self-rotating states, supported by ambient illumination. Quantitative analysis shows that increased light intensity, the contraction coefficient, and the elastic coefficient enhance the self-rotating frequency, while more damping decreases it. The track radius exhibits a non-monotonic effect. The initial tangential velocity has no impact. The reliable self-rotating performance under steady light suggests potential applications in periodic motion-demanding fields, especially in the construction industry where energy dissipation and utilization are of utmost urgency. Furthermore, this spatial slider system possesses the ability to rotate and self-vibrate, and it is capable of being adapted to other non-circular curved tracks, thereby highlighting its flexibility and multi-use capabilities.

Implications of White Light-Emitting Diode-Based Photoirradiation on Green Synthesis of Silver Nanoparticles by Methanol- and Aqueous-Based Extracts of Bergenia ciliata Leaves.

Bergenia ciliata (BC) is a perennial herb that is frequently used as a traditional medicine. Its leaves and rhizomes are reported to have significant antioxidant, metal-reducing, and chelating properties. Although the rhizomes have the potential to synthesize silver nanoparticles (AgNPs), the leaves are yet to be studied for the green synthesis of metal nanoparticles. Likewise, photoirradiation also plays a significant role in the green synthesis of metal nanoparticles. In the current study, we intended to demonstrate the implications of photoirradiation by white light-emitting diode (LED) on the aqueous and methanol extracts (AE and ME, respectively) of BC leaf-mediated green synthesis of AgNPs. In this regard, the AgNP synthesis of the two extracts was performed in the dark and under 250-lumen (lm) and 825 lm LED bulbs. The physicochemical characterization of the synthesized nanoparticles was also performed, wherein percent nanoparticles yield, morphology of the nanoparticles, shape, size, percent elemental composition, crystallinity, and nanoparticle stability were studied. The nanoparticle-synthesizing potential of the two extracts contradicted significantly in the presence and absence of light, while the AE produced a significantly high number of nanoparticles in the dark (17.26%), and increasing light intensities only attenuated the nanoparticle synthesis, whereas ME synthesized comparatively negligible silver nanoparticles in the dark (1.23%). However, increasing light intensities significantly enhanced the number of nanoparticles synthesized in 825 lms (7.41%). The GCMS analysis further gave a comparative insight into the phytochemical composition of both extracts, wherein catechol and pyrogallol were identified as major reducing agents for nanoparticle synthesis. The influence of light intensities on the physiochemical characterization of AgNPs was predominant. While the size of both the AE- and ME-mediated AgNPs increased considerably (20-50 nm diameter) with increasing light intensities, the percent of silver atoms decreased significantly with increasing light intensities in both the AE- and ME-mediated AgNPs with ranges of 13-18% and 14-24%, respectively. The nanoparticle stability studies suggested that both the AE- and ME-mediated AgNPs were stable for up to 15 days when stored at 4 °C. The stability of both nanoparticles was attributed to the presence of a wide range of phytochemicals. In conclusion, the AE of BC leaves was reported to have significantly higher AgNP-synthesizing potential as compared to the ME. However, AE-mediated AgNP synthesis is attenuated by photoirradiation, whereas ME-mediated AgNP synthesis is enhanced by photoirradiation. The photoirradiation by white LED light increases the size of the AgNPs, while the percent silver composition declines, irrespective of the extract type. Both extracts, however, have nanoparticle stabilizing potential, thereby producing stable nanoparticles.

Phytoplankton cell-states: multiparameter fluorescence lifetime flow-based monitoring reveals cellular heterogeneity.

Phytoplankton are a major source of primary productivity. Their photosynthetic fluorescence are unique measures of their type, physiological state, and response to environmental conditions. Changes in phytoplankton photophysiology are commonly monitored by bulk fluorescence spectroscopy, where gradual changes are reported in response to different perturbations, such as light intensity changes. What is the meaning of such trends in bulk parameters if their values report ensemble averages of multiple unsynchronized cells? To answer this, we developed an experimental scheme that enables tracking fluorescence intensities, brightnesses, and their ratios, as well as mean photon nanotimes equivalent to mean fluorescence lifetimes, one cell at a time. We monitored three different phytoplankton species during diurnal cycles and in response to an abrupt increase in light intensity. Our results show that we can define specific subpopulations of cells by their fluorescence parameters for each of the phytoplankton species, and in response to varying light conditions. Importantly, we identify the cells undergo well-defined transitions between these subpopulations. The approach shown in this work will be useful in the exact characterization of phytoplankton cell states and parameter signatures in response to different changes these cells experience in marine environments, which will be applicable for monitoring marine-related environmental effects.

The role of light intensity in water transport and homeostasis across different vapor pressure deficit conditions

Vapor pressure deficit (VPD) directly affects the driving force of plant water movement by altering the water potential gradient between the atmosphere and plants and indirectly influences the resistance to water movement by regulating plant structure. Concurrently, light intensity modulates both the driving force and resistance to water movement by regulating plant morphology and nonstructural carbohydrate synthesis. Despite significant advances in the understanding of the regulatory effects of VPD on water absorption and transport in tomatoes, the effect of light intensity regulation under varying VPDs on water transport and homeostasis remains to be clarified. Here, we investigated the effects of two light intensities (L300; 300 µmol m–2 s–1, L600; 600 µmol m–2 s–1) on plant anatomy, physiological traits, hydraulic properties, and expression of plasma membrane intrinsic proteins (PIPs) and tonoplast intrinsic proteins (TIPs) in tomatoes subjected to long-term high and low VPDs. In addition, we analysed the correlations and path coefficients of these indicators. These results indicate that higher light intensity reduces resistance to water movement by enhancing root morphology, vessel parameters in roots and stems, leaf vein density, stomatal morphology, physiological traits, and expression of SlTIPs and SlPIPs in both roots and leaves. Concurrently, increased light intensity boosts the driving force of water movement by amplifying the water potential difference and transpiration under low VPD. However, under high VPD, elevated light intensities create a larger water potential difference, prompting plants to reduce this excessive force by decreasing transpiration and stomatal conductance, thereby maintaining water homeostasis. These findings suggest that light intensity can effectively regulate water homeostasis by dynamically optimising plant structure, hydraulic properties, and the expression of SlTIPs and SlPIPs across different VPDs, providing a theoretical foundation for practical light intensity management in agriculture.

Aggregation−induced red−shift emission from self-assembled planar naphthalene diimide dye: Interlayer in a Schottky-type photodiode and DFT studies

In this study, a planar, soluble, thin film-forming and self-assembled small naphthalene diimide (3) molecule with a subtle moiety at the imide-nitrogen was synthesized, and applied for the first time in literature as an interfacial layer between Al and p-Si layers in a Schottky-type photodiode. The morphology of the compound was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thin film structure and morphology affected the optical and electrical properties. The energy levels of the highest occupied molecular orbitals and lowest unoccupied molecular orbitals of 3 were calculated as −6.14 eV and −4.02 eV, corresponding to the band gap of 2.12 eV consistent with density functional theory (DFT) results. Differential scanning calorimetry (DSC) studies revealed a relatively high Tg value at 208 °C, indicating high-temperature applicability of the crystalline structure. The I–V measurements of Al/3/p-Si heterostructure were performed under dark and various light power intensities. The current steadily rose with each incremental 20 mW increase in light intensity. The reverse current increased almost 10-fold at 100 mW/cm2 illumination compared to dark measurement. The photodiode's responsivity, photosensitivity, and detectivity factors were elucidated. The photodiode's characteristic values, such as Io, n, ϕb, and Rs, were obtained as 3.50 × 10−6 A, 8.24, 0.588 eV and 2.266 kΩ, respectively. The fabricated Schottky-type diode showed promising results for the optoelectronic field. The compound's perfect solubilities in a wide range of solvents, processability, excellent chemical and photochemical stabilities, and exciting optical, thermal and electrochemical properties make it an ideal candidate for thin film and molecular electronics applications.

Adaptation of indoor ornamental plants to various lighting levels in growth chambers simulating workplace environments

Despite the growing interest in indoor greenery and its positive effects on occupants’ well-being, there is limited knowledge on the optimal light levels for indoor plants that ensure energy efficiency and sustainable growth. This study explored the survival of ornamental plants under low-light conditions typical of indoor workplaces without daylight and investigated the impact of increased light intensity or extended day length on their growth. Three species of foliage plants (Epipremnum aureum, Pachira aquatica, and Rhaphidophora tetrasperma) were cultivated in growth chambers with three different lighting schemes. The results showed that plants sustained growth with 6.8 μmol m−2 s−1 white LED light for 9 h/day, suggesting that extra lighting might not be necessary for shade-tolerant species in offices. In this environment, plants maintained efficient photosynthesis under low illumination by increasing their specific leaf area. Elevating the light to 20.1 μmol m−2 s−1 and extending the day length to 18 h/day enhanced the plants’ relative growth rate. Climbing plants allocated more biomass to stems, resulting in a lower leaf weight ratio and noticeably altering their appearance. This study demonstrates that customized lighting strategies effectively support indoor greening goals, like adjusting intensity for energy savings or adding light for greening large spaces.

Comparative study of cadmium telluride solar cell performance on different TCO‐coated substrates under concentrated light intensities

AbstractConcentrating photovoltaics is an attractive route for achieving high power output with thin film solar cells, using low‐cost optics. In this work, the performance of CdTe:As thin film solar cells on two different transparent conducting oxide (TCO)‐coated substrates is investigated and compared under varying concentrated light intensities (1–6.3 Suns). Samples tested had CdZnS/CdTe:As devices deposited atop of either a soda‐lime glass with a fluorine‐doped tin oxide TCO or an ultra‐thin glass (UTG) with an aluminium zinc oxide TCO and ZnO high‐resistive transparent (HRT) layer. Device current density was found to increase linearly with increased light intensities, for both sample configurations. Power conversion efficiencies of both device samples decreased with increased light intensity, due to a decrease in fill factor. The fill factor, for both sample configurations, was affected by reducing shunt resistance with increasing illumination intensity. The two device types performed differently at the high illumination intensities due to their series resistance. Light‐soaking devices under 6.3 Suns illumination intensity for 90 min showed no significant performance degradation, indicative of relatively stable devices under the highest illumination intensity tested. Efficiency limiting factors are assessed, evaluated and discussed.

Climate Change Stressors, Phosphate Limitation, and High Irradiation Interact to Increase Alexandrium minutum Toxicity and Modulate Encystment Rates.

The changes in the cell physiology (growth rate, cell size, and cell DNA content), photosynthetic efficiency, toxicity, and sexuality under variable light and nutrient (phosphates) conditions were evaluated in cultures of the dinoflagellate Alexandrium minutum obtained from a red tide in the Ría de Vigo (NW Spain). The cells were grown at low (40 and 150 µE m-2 s-1), moderate (400 µE m-2 s-1), and high (800 µE m-2 s-1) light intensities in a medium with phosphate (P+) and without (P-). Cultures were acclimated to the irradiance conditions for one week, and the experiment was run for ~1 month. The cell size and DNA content were monitored via flow cytometry. Two different clonal strains were employed as a monoculture (in a P- or P+ medium) or, to foster sexuality and resting cyst formation, as a mixed culture (only in a P- medium). A. minutum growth was favored by increasing light intensities until 400 µE m-2 s-1. The DNA content analyses indicated the accumulation of S-phase cells at the highest light intensities (400 and 800 µE m-2 s-1) and therefore the negative effects on cell cycle progression. Only when the cells were grown in a P- medium did higher light intensities trigger dose-dependent, significantly higher toxicities in all the A. minutum cultures. This result suggests that the toxicity level is responsive to the combined effects of (high) light and (low) P stress. The cell size was not significantly affected by the light intensity or P conditions. The optimal light intensity for resting cyst formation was 150 µE m-2 s-1, with higher irradiances reducing the total encystment yield. Encystment was not observed at the lowest light intensity tested, indicative of the key role of low-level irradiance in gamete and/or zygote formation, in contrast to the stressor effect of excessive irradiance on planozygote formation and/or encystment.

Liquid-solid heterojunction constructing bio-sensory floating-gate OECTs

The floating-gate organic electrochemical transistor (OECT) employs a distinct signal acquisition and amplification structure. This design offers two primary advantages: firstly, it mitigates the effects of non-specific physical adsorption during the sensing process and prevents contamination of the electrolyte solution by side reaction products, thereby enhancing detection accuracy. Secondly, it allows for an increased gate/electrolyte capacitance, optimizing the OECT’s signal amplification capability. Until now, optimizing the sensing electrode and control gate remains ambiguous. This current research uses a photosensitive liquid-solid heterojunction as the control gate. This choice is based on the observation that the photovoltage of −0.43 V remains unaffected by variations in electrode area, and any reduction in photocurrent due to area reduction can be offset by an increase in light intensity. Furthermore, given that the capacitance value of liquid-solid heterojunctions (4.386×10−2 F) significantly surpasses other components in equivalent circuits during light radiation, these heterojunctions can be considered self-driving and quasi-non-polarized. We confirmed the viability of this structural configuration through cortisol molecule detection. The potential application of this photosensitive liquid-solid heterojunction lies in constructing high-density and high-stability biosensors, a necessity in practical applications.