Low Light Intensity Research Articles

Unconventional Photocapacitor Utilizing Metal-Organic Dye Capable of Operating in Low Intensity Light.

The development of devices capable of storing energy harnessed from photons is on the rise, owing to the increasing global energy demand for smart systems. The majority of reports in this field cover the use of integrated type devices, which houses a separate photovoltaic module and supercapacitor or battery. Herein, we are reporting a photocapacitor with a simple two-electrode design, capable of operating without a conventional electrolyte or metal ions. The device prepared using a layered architecture of reduced graphene oxide (rGO) and TiO2 on both electrodes and N719 dye as a photoactive material resulted in a capacitance of 20.3 F/g. Optimizing the number of rGO and TiO2 layers led to an enhanced diffusion of photons to the N719 dye, thus leading to better absorption characteristics. Interestingly, the developed photocapacitor could also be recharged with low intensity light (<300 lx). The capacitance was further improved by more than twice (43.5 F/g) upon substituting the back electrode with conducting carbon and the capacity retention was over 93% after 50 cycles. The current work opens wide possibilities for developing efficient two-electrode photocapacitors.

Dual-Mode ZnO/SnSe Heterojunction Devices with Integrated Bipolar Response Photodetectors and Artificial Optoelectronic Synapses for in-Sensor Computing.

Optoelectronic synapse devices (OESDs) inspired by human visual systems enable to integration of light sensing, memory, and computing functions, greatly promoting the development of in-sensor computing techniques. Herein, dual-mode integration of bipolar response photodetectors (PDs) and artificial optoelectronic synapses based on ZnO/SnSe heterojunctions are presented. The function of the fabricated device can be converted between the PDs and OESDs by modulating the light intensity. As a PD, the polarity of the output current can be switched by tuning the laser wavelength and intensity, which is attributed to the competition between the photovoltaic and photothermoelectric effects in the ZnO/SnSe heterojunction. As an OESD, the device exhibits versatile photonic synaptic characteristics at low light intensity based on the defect-dominant carrier trapping/de-trapping processes, including short/long-term plasticity and learning experience behaviors. More importantly, benefitting from the outstanding synaptic responses, logic functions including "AND" and "OR" are implemented through the in-sensor computing architecture. This work supplies a novel route to realize complex functionality in one device and offers effective strategies for developing in-sensor computing.

Optimizing Phaeodactylum tricornutum cultivation: integrated strategies for enhancing biomass, lipid, and fucoxanthin production

BackgroundPhaeodactylum tricornutum is a versatile marine microalga renowned for its high-value metabolite production, including omega-3 fatty acids and fucoxanthin, with emerging potential for integrated biorefinery approaches that encompass biofuel and bioproduct generation. Therefore, in this study we aimed to optimize the cultivation conditions for boosting biomass, lipid, and fucoxanthin production in P. tricornutum, focusing on the impacts of different nutrient ratios (nitrogen, phosphorus, silicate), glycerol supplementation, and light regimes.ResultsOptimized medium (− 50%N%, + 50% P, Zero-Si, 2 g glycerol) under low-intensity blue light (100 μmol m⁻2 s⁻1) improved biomass to 1.6 g L⁻1, with lipid productivity reaching 539.25 mg g⁻1, while fucoxanthin increased to 20.44 mg g−1. Total saturated fatty acid (ΣSFA) content in the optimized culture increased approximately 2.4-fold compared to the control F/2 medium. This change in fatty acid composition led to improved biodiesel properties, including a higher cetane number (59.18 vs. 56.04) and lower iodine value (53.96 vs 88.99 g I2/100 g oil). The optimized conditions also altered the biodiesel characteristics, such as kinematic viscosity, cloud point, and higher heating value.ConclusionOur optimization approach reveals the significant potential of P. tricornutum as a versatile microbial platform for biomass, lipid, and fucoxanthin production. The tailored cultivation strategy successfully enhanced biomass and lipid accumulation, with notable improvements in biodiesel properties through strategic nutrient and light regime manipulation. These findings demonstrate the critical role of precise cultivation conditions in optimizing microalgal metabolic performance for biotechnological applications.

NIR-Reflective Black Photonic Films Designed for Effective LiDAR Recognition.

Conventional dark-tone paints absorb both visible light and near-infrared (NIR) wavelengths, posing a challenge for light detection and ranging (LiDAR) recognition in autonomous driving. To overcome this issue, various chemical and structural coating materials have been explored to selectively reflect NIR. In this study, we newly propose colloidal photonic crystals with a stopband in the NIR range, fabricated through the spontaneous formation of crystalline arrays of silica particles dispersed in a photocurable resin, as a potential solution. The stopband position is finely adjusted by controlling the volume fraction of particles, and the translucent films are rendered black by incorporating carbon black nanoparticles into the interstitial regions. By optimizing the concentration of carbon black, we achieve a balance of low visible light and high LiDAR intensity. These black photonic films demonstrate superior LiDAR intensity compared to commercial dark-tone paints and perform on par with the perylene black-deposited white coating, one of the most promising LiDAR-assistive materials currently available, under normal reflection conditions. Additionally, the photonic films are highly durable, thermally stable, nontoxic, and environmentally friendly, making them promising candidates for LiDAR-assistive coatings.

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.

Chloroplast arrangement in finger millet under low-temperature conditions.

Finger millet, a C4 plant with mesophyll and bundle sheath cells, has been cultivated at high altitudes in the Himalayas owing to its adaptability to stressful environments. Under environmental stresses such as high light and drought, finger millet mesophyll chloroplasts move toward the bundle sheath, a phenomenon known as aggregative arrangement. To investigate the effect of low temperatures on mesophyll chloroplast arrangement in finger millet, we conducted microscopic observations and photochemical measurements using leaves treated at different temperatures in light or darkness, with or without pharmacological inhibitors. Abscisic acid (ABA) content was also quantified. Chloroplast aggregative arrangement was induced at 5 °C in a light- and actin-dependent manner. This response required a lower intensity of blue light than that previously observed at moderate temperatures. Low temperature significantly reduced the maximum quantum efficiency of photosystem II and increased leaf ABA content in the light. Conversely, in the absence of blue light at low temperatures or under actin-inhibited conditions, mesophyll chloroplasts exhibited a doughnut-like arrangement, characterized by a distribution away from the bundle sheath side. In finger millet, mesophyll chloroplasts move toward the bundle sheath through a blue light and actin-based mechanism at low temperatures. The doughnut-like arrangement appears to be a contingent phenomenon that manifests when the dispersion of mesophyll chloroplasts toward the bundle sheath is impeded. The aggregative arrangement is a response to various environmental stresses, including low temperatures, and may be advantageous for finger millet seedlings in mitigating photoinhibition during cool mornings.

In vitro anti-biofilm efficacy of therapeutic low dose 265nm UVC.

Preclinical studies have confirmed the safety and efficacy of narrowband low-intensity ultraviolet C light (UVC) in managing bacterial corneal infection. To further consolidate these findings, the present study aimed to explore in vitro anti-biofilm efficacy of low-intensity UVC light for its potential use in biofilm-related infections. Pseudomonas aeruginosa biofilm was grown in chamber well slides for 48h and exposed to one of the following challenges: UVC (265nm wavelength, intensity 1.93mW/cm2) for 15s, 30 s, 60 s or 120s duration, 70% propanol (positive control), or no exposure (negative control). Bacterial LIVE/DEAD staining was conducted at 1h, 4h, 6h and 8h after challenge exposures to assess the temporal pattern of biofilm inactivation, and slides were imaged using confocal microscopy. Treatment efficacy was quantified by dead biofilm biomass (volume/area - μm3/μm2) for different treatment groups at each time point. At each time point post-exposure, dead biofilm biomass was consistently higher in the alcohol- and UVC-challenged groups than in the unchallenged control (p<0.05), suggesting a sustained biocidal impact after a given challenge. The quantity of dead biofilm biomass did not differ between UVC groups at any time point (p>0.05). Observed by confocal microscopy, UVC-exposed biofilm demonstrated predominantly intermediate-stage biofilm (i.e., dying state) at 1h, which progressed to dead biofilm by 4h. Low doses of UVC demonstrated potent anti-biofilm activity, even in exposures as short as 15s, the dose that has previously been deemed to be effective in managing corneal infection in vivo. These data support the potential for this UVC light-based technology to serve as an affordable, convenient, and effective means of treating ocular infections associated with bacterial biofilm.

Uniform dipole resonance and suppressed quadrupole resonance for constant transmittivity full phase control plasmonic metasurfaces

Transmission-type plasmonic phase metasurfaces utilizing the Pancharatnam-Berry (PB) phase require constant transmittivity with complete phase variation from 0 to 2. Usually, this is achieved by rotating metallic nanoparticles in an otherwise uniform lattice arrangement. However, this rotation and the chosen lattice structure cause a significant change in the transmittivity, resulting in a lower intensity of light with certain phases and a higher intensity for other phases. Even though they are called full phase metasurfaces, their intensities can be near maximum or near minimum depending on the rotation and the lattice structure. We show that it is possible to achieve full phase constant transmittivity metasurfaces using the PB phase and the most elementary metallic anisotropic nanoparticles (elliptical) by inserting a thin metal sheet between the nanoparticles and the substrate. Without this metal sheet, while full phase control could be achieved by merely rotating the particles, the transmittivity varies by about 50% depending on the nanoparticles’ orientation. With the metal sheet, full phase control from 0-2 with a transmittivity variation of only 13%, even in a square lattice, is demonstrated with simulations and experiments. We show that this is due to the annihilation of quadrupole resonances along with broader uniform dipole resonance in the case of the nanoparticles with the metal sheet below. We also show that precise phase control is possible by generating varieties of orbital angular momentum beams and complex beams in the visible spectrum using nanofabricated metasurfaces.

Effect of incident light and light gradients on eicosapentaenoic acid distribution between lipid classes in Nannochloropsis oceanica

AbstractCommercial production of eicosapentaenoic acid (EPA) from photoautotrophic microalgae like Nannochloropsis oceanica requires higher productivity and larger scales to reduce costs. Improving productivity can be achieved by increasing biomass concentrations, which creates light gradients in the reactor depending on the culture’s acclimation and the reactor geometry. These light gradients affect physiology, lipid synthesis, but also the distribution of fatty acids between lipid classes. In this study we evaluated the combined effect of the incident light intensity and light gradient on growth, biochemical composition, and fatty acid distribution between lipid classes. A total of 13 cultivations were performed in continuous mode using three different incident light intensities (200, 670, and 1550 μmol photons m−2 s−1) and four dilution rates (from 0.29 to 0.75 day−1). Reducing dilution rates resulted in higher biomass concentrations, steeper light gradients, and lower average light intensities. Increasing incident light intensity improved biomass productivity from 0.5 to 1.8 g L−1 day−1, while the biomass yield on light decreased from 1.05 to 0.44 g mol−1. Lowering average light intensities decreased the triglyceride content from 11.1 to 1.5% w/w, and increased the galactolipid content, mainly monogalactosyldiacylglycerol, up from 3.1 to 5.1% w/w. Total EPA contents did not decrease at low incident light but decreased by 28% at highly saturating light, both relative to medium incident light. The EPA content in polar lipids increased at lower average light intensities, and decreased in the neutral fraction simultaneously. These results highlight the tight regulation of EPA content between lipid polar and neutral fractions under different light regimes. Graphical Abstract

Stable and Lead‐Free Perovskite Hemispherical Photodetector for Vivid Fourier Imaging

AbstractThe filterless single‐pixel imaging technology is anticipated to hold tremendous competitiveness in diverse imaging applications. Nevertheless, achieving single‐pixel color imaging without a filter remains a formidable challenge. Here a lead‐free perovskite hemispherical photodetector is reported for filterless single‐pixel color imaging. Through passivating the active vacancy and antisite defects with functional chemical groups, the trap density of the perovskite film can be dramatically reduced to half of the pristine one, which results in a stable device with 0.69 nA standard deviation (SD) of the current fluctuations for over 10 000 s. The exceptional stability and remarkable low light response capability of passivated lead‐free perovskite devices ensure reliable and repeated distinguishment to high‐frequency color information of Fourier patterns. High‐resolution color imaging with 256 × 256 pixels can be achieved by integrating the Bayer template with Fourier patterns and designing a corresponding color restoration algorithm. Notably, its imaging quality surpasses commercial silicon photomultiplier tubes (SiPMs) under low light intensities or high‐temperature conditions as demonstrated by the larger signal‐to‐noise ratio (SNR). This work presents a novel approach for applying perovskite photodetectors in single‐pixel color imaging, propelling the advancement of filterless color imaging technology.

Growth and cation uptake in turf-type tall fescue (Festuca arundinacea Schreb.) are affected by low light intensity

Growth and cation uptake in turf-type tall fescue (Festuca arundinacea Schreb.) are affected by low light intensity

EFFECT OF COLLOIDAL SOLUTIONS OF METAL NANOPARTICLES AND LASER IRRADIATION ON BIOLOGICAL ACTIVITY OF THE EDIBLE MEDICINAL MACROFUNGUS Pleurotus eryngii (PLEUROTACEAE, AGARICALES) IN VITRO

Aim. The goal of our work was to study the effect of colloidal solutions of metal nanoparticles (NPs) on the synthesis of mycelial mass, polysaccharides, phenolic compounds, and the antioxidant activity of the edible medicinal macrofungus Pleurotus eryngii, as well as the effects of photocatalytic activity of NPs after exposure to low-intensity laser radiation under submerged cultivation conditions. Methods. Traditional mycological methods and unique photobiological methods were used. The effect of light on the biosynthetic and biological activity of P. eryngii was studied using low-intensity coherent monochromatic blue laser light (λ=488 nm). The experiment used colloidal solutions of metal nanoparticles (FeNPs, MgNPs, AgNPs) based on the method of volumetric electric spark dispersion of metals patented in Ukraine. Results. Treatment of the inoculum with colloidal solutions of FeNPs and MgNPs increased the amount of mycelial mass of P. eryngii by 38–53%, while irradiation of the inoculum with blue laser light (λ=488 nm) in a medium with NPs increased the growth activity of the P. eryngii mycelium by 6.8‒18.2%. All nanoparticles suppressed the biosynthesis of extracellular polysaccharides. The most significant effect was observed with the addition of MgNPs – 21.4%. While the use of photoinduced nanoparticles stimulated the synthesis of extracellular polysaccharides, the most excellent effect was observed for MgNPs – 100%. The addition of all NPs to the P. eryngii inoculum reduced the amount of intracellular polysaccharides in the mycelial mass by 9.4% (MgNPs) and by 22% (AgNPs). The use of NPs photoinduced by blue laser light increased the amount of intracellular polysaccharides in the mycelial mass of P. eryngii by 28.1% (AgNPs) and by 50% (MgNPs). Treatment of the inoculum with colloidal solutions of AgNPs, FeNPs and MgNPs and laser light-induced nanoparticles increased the amount of phenolic compounds in the mycelial mass. The highest total phenolic content (TPC) values in ethanol extracts were recorded when using photoinduced MgNPs − 59.51±0.4 mg GAEs/g dry mass. Conclusions.The results of the studies provided grounds to consider metal nanoparticles (FeNPs, MgNPs), and lowintensity blue laser radiation as promising regulators of the synthesis of polysaccharides and phenolic compounds in the mycelial mass of P. eryngii under submerged cultivation conditions.

СОХРАНЕНИЕ БИОРАЗНООБРАЗИЯ РОДА SYRINGA L. В КОЛЛЕКЦИИ IN VITRO ГБС РАН

Syringa L. is a genus of woody plant species cultivated in temperate climate regions mainly for ornamental spring flowering. In Russia and abroad, the breeding work is focused on several areas, including original flowering, winter hardiness, disease resistance, etc. Conservation of plant genetic diversity, including ornamental crops, for current and future breeding programs is the main task of botanical gardens and other research centers. The biotechnological method is considered one of the most effective and reproducible ways to preserve the plant gene bank. Tsitsin Main Botanical Garden’s in vitro collection of the genus Syringa L. includes more than two hundred accessions (species, subspecies, cultivars, and selected plants). During the research, the methods of in vitro cultivation were improved for this crop. The morphogenesis and morphometric parameters were analyzed, when cultivated lilac cultivars on the media with different growth regulators at the micropropagation stage. The analysis of growth regulators used for lilac micropropagation (6-benzylaminopurine, meta-Topolin, tidiazuron) showed that the highest values of essential micropropagation parameters (height of microshoots, multiplication rate, etc.) were obtained when cultivated on nutrient media with the addition of meta-Topolin. Murashige-Skoog medium supplemented with meta-Topolin at the concentrations of 0.5 mg/L and 1.0 mg/L was found effective for lilac micropropagation. The use of meta-Topolin in a medium induced adventitious shoot formation at the base of explants and activation of axillary buds on them. The technique of slow growth preservation was improved for the representatives of the genus Syringa. Cultivation under low light intensity (0.7 Klux) and temperature (5–7°C) on a medium added with retardant (4 mg/L of chlorcholine chloride) significantly enlarged subcultivation duration (up to 2.0 years and more) and contributed to preserving the viability of explants (81% on average).

Unraveling Mechanism and Enhancing Selectivity of a RuII-bis-bipyridyl-morphocumin Complex with RAFT-Generated Glycopolymer Exploiting Warburg Effect in Cancer.

The Warburg effect, which generates increased demand of glucose in cancer cells is a relatively underexplored phenomenon in existing commercial drugs to enhance uptake in cancer cells. Here, we present a chemotherapeutic strategy employing a Ru(II)-bis-bipyridyl-morphocumin complex (2) encapsulated in a self-assembling glucose-functionalized copolymer P(G-EMA-co-MMA) (where G=glucose; MMA=methyl methacrylate; EMA=ethyl methacrylate), designed to exploit this effect for enhanced selectivity in cancer treatment. The P(G-EMA-co-MMA) polymer, synthesized via reversible-addition fragmentation chain transfer (RAFT) polymerization, has a number average molecular weight (Mn,NMR) of 8000 g/mol. Complex 2, stable in aqueous media, selectively releases a cytotoxic, lysosome-targeting compound, morphocumin, in the presence of excess hydrogen peroxide (H₂O₂), a reactive oxygen species (ROS) prevalent in tumor microenvironments. Additionally, complex 2 promotes ROS accumulation, which may further enhance morphocumin release through a synergistic domino effect. Comparative studies reveal that 2 outperforms its curcumin Ru(II) complex (1) analog in solution stability, organelle specificity, and cellular mechanisms. Both 1 and 2 exhibit phototherapeutic effects under low-intensity visible light, but their chemotoxicity significantly increases with incubation time in the dark, highlighting the superior chemotherapeutic efficacy of the O,O-coordinating Ru(II) ternary polypyridyl complexes. Complex 2 induces apoptosis via the intrinsic pathway and shows a 9-fold increase in selectivity for pancreatic cancer cells (MIA PaCa-2) over non-cancerous HEK293 cells when encapsulated in the glucose-conjugated polymer (DP@2). Glucose deprivation in the culture medium further enhances drug efficacy by an additional 5-fold. This work underscores the potential of glucose-functionalized polymers and ROS-responsive Ru(II) complexes in targeted cancer therapy.

Escape of etiolated hypocotyls of cotton (Gossypium hirsutum) from the unilateral high intensity blue light after being pulled out from the soil.

Plant stems grow towards the incident light in response to unilateral blue light to optimize photosynthesis. However, our findings reveal that unilateral high-intensity blue light (HBL) triggers backlit lodging in etiolated cotton (Gossypium hirsutum ) hypocotyls when they are pulled approximately 1.5cm from the soil. Phenotypic analysis indicated that stomata on the lit side were open, while those on the shaded side were closed under unilateral HBL. To investigate the relationship between stomatal movement and backlit lodging, we applied abscisic acid (ABA), hydrogen peroxide (H2 O2 ), and lanthanum chloride (LaCl3 ) to the lit side, and cytokinins (6-BA) and ascorbic acid (ASA) to the shaded side. Results showed that all these treatments inhibited the backlit lodging phenomenon, specifically, ABA, H2 O2 , and LaCl3 reduced stomatal opening on the lit side, while 6-BA and ASA enhanced stomatal opening on the shade side. These results demonstrate that HBL-induced asymmetrical stomatal opening on the lit and shade side of hypocotyl supports the backlit lodging phenomenon. Notably, maize (Zea mays ), which lack stomata in the hypocotyl did not exhibit HBL-induced backlit lodging, whereas soybean (Glycine max ), which has stomata in its etiolated hypocotyl, displayed a similar phenotype to that of cotton. Additionally, while both red light and low-intensity blue light (LBL) can induce stomatal opening, they do not trigger the backlit lodging phenomenon. These findings suggest that backlit lodging is a unique HBL-dependent response, but the mechanism need further investigation.

The Impact of Café Lighting on Customer Comfort Perception

The evolution of cafés as multifunctional spaces for dining, socializing, and working has significantly influenced the standards for lighting. This study investigates the light intensity and customer comfort at Threelogy Coffee and Zybrick Coffee and Cantina, two cafés characterized by markedly different designs and lighting conditions. Field surveys and light intensity measurements were conducted to evaluate the lighting conditions at both locations, while questionnaires were used to assess visitor perceptions of comfort. At Threelogy Coffee, light intensity levels are notably high, with indoor measurements ranging from 360 to 465 lux and reaching up to 34,705 lux in semi-outdoor areas. This high level of illumination is attributed to natural sunlight and the reflective properties of white surfaces on ceilings and walls. Conversely, Zybrick Coffee and Cantina exhibits lower light intensity, with indoor levels between 65 and 70 lux and semi-outdoor areas ranging from 240 to 670 lux. This reduced illumination is due to limited natural light and the use of dark wall materials. Survey results reveal that customers to Threelogy Coffee generally express satisfaction with the bright lighting, although there is a potential risk of long-term monotony. In contrast, customers to Zybrick Coffee and Cantina report comfort despite the dim lighting, which is attributed to the private and intimate atmosphere fostered by the café's design. Both cafés exhibit comparable levels of overall comfort, highlighting the significance of atmospheric design elements, in addition to lighting, in creating a positive customer experience.

The interactive effects between far-red light and temperature on lettuce growth and morphology diminish at high light intensity.

Phytochromes (PHYs) play a dual role in sensing light spectral quality and temperature. PHYs can interconvert between the active Pfr form and inactive Pr form upon absorption of red (R) and far-red (FR) light (Photoconversion). In addition, active Pfr can be converted to inactive Pr in a temperature-dependent manner (Thermal Reversion). Recent studies have shown that FR light and temperature can interactively affect plant growth and morphology through co-regulating phytochrome activities. These studies were primarily conducted under relatively low light intensities. As light intensity increases, the impact of thermal reversion on phytochrome dynamics decreases. However, the light intensity dependency of the interactive effects between FR light and temperature on plant growth and morphology has not been characterized. In this study, lettuce (Lactuca sativa L.) 'Rex' was grown under two total photon flux densities (TPFD; 400-800 nm) (150 and 300 μmol m-2 s-1) x three temperatures (20, 24, and 28°C) x two light spectra (0 and 20% of FR light in TPFD). Our results showed that the effects of FR light on leaf, stem, and root elongation, leaf number, and leaf expansion were dependent on temperature at lower TPFD. However, the magnitude of the interactive effects between FR light and temperature on plant morphology decreased at higher TPFD. Particularly, at a lower TPFD, FR light stimulated leaf expansion and canopy photon capture only under a cooler temperature of 20°C. However, at a higher TPFD, FR light consistently increased total leaf area across all three temperatures. Plant biomass was more strongly correlated with the total number of photons intercepted by the leaves than with the photosynthetic activities of individual leaves. FR light decreased the contents of chlorophylls, carotenoids, flavonoids, and phenolics, as well as the total antioxidant capacity. In contrast, warmer temperatures and high light intensity increased the values of these parameters. We concluded that the interactive effects between FR light and temperature on plant growth and morphology diminished as total light intensity increased. Additionally, the combination of high light intensity, warm temperature, and FR light resulted in the highest crop yield and antioxidant capacity in lettuce.

CLFNet: a multi-modal data fusion network for traffic sign extraction

Abstract When using image data for signage extraction, poor visibility conditions such as insufficient light, rainy days, and low light intensity are encountered, leading to low accuracy and poor boundary segmentation in vision-based detection methods. To address this problem, we propose a cross-modal latent feature fusion network for signage detection, which obtains rich boundary information by combining images with light detection and ranging depth images, thus compensating for the pseudo-boundary phenomenon that may occur when using a single RGB image segmentation. First, HRNet is utilized as the backbone network to extract the boundary information of the point cloud depth map and RGB image by introducing the boundary extraction module; Second, the sensitivity to the boundary is enhanced by applying the feature aggregation module to deeply fuse the extracted boundary information with the image features; Finally, boundary Intersection over Union (IOU) is introduced as an evaluation index. The results show that the method performs more superiorly compared to the mainstream RGBD network, with an improvement of 5.5% and 6.1% in IOU and boundary IOU, and an accuracy of 98.3% and 96.2%, respectively, relative to the baseline network.

Insight into gain and transient response characteristics of AlGaN/GaN hetero-junction based UV photodetectors: Case study on the role of incident light intensity

Gain and response speed are two key performance parameters for high sensitivity photodetectors (PDs). However, the effect of incident light intensity on gain and transient response properties of AlGaN/GaN hetero-junction based PDs are still not fully understood. Here, we design and fabricate an AlGaN/GaN hetero-junction based ultraviolet (UV) PD with interdigitated electrodes formed by a conductive two-dimensional electron gas (2DEG) channel, which exhibits a low dark current of 2.92 × 10−11 A and a high responsivity of 3060 A/W at 10 V bias. The high-gain AlGaN/GaN 2DEG PD has a similar working mechanism to those of traditional phototransistors, but its device architecture is evidently simplified. By investigating the variation of gain and transient response characteristics of the 2DEG PD as a function of incident UV light intensity, it has been concluded that the gain of the PD in a low-light intensity region is dominated by hole accumulation-induced electron escape from the 2DEG, while in a high-light intensity region, the gain is dominated by photoconductivity effect and limited by carrier recombination. This study provides guidance for future practical applications of AlGaN/GaN-based PDs in complex UV illumination environments.

Sustainable lipids production in algal-bacterial consortia under low light intensity: Regulation of light–dark on fatty acid composition

Sustainable lipids production in algal-bacterial consortia under low light intensity: Regulation of light–dark on fatty acid composition