Lighting Research Articles

Model-based optimisation of microalgae growth under high-intensity and high-frequency pulsed light conditions

High-frequency pulsed light is a promising tool to enhance the performance of microalgae cultivation under artificial illumination. The quantitative comprehension of the effects of pulsed light on cell growth is essential to maximise biomass productivity and to increase the efficiency of artificial light for microalgae growth. In this work, a mathematical model is developed to capture the effect of high-frequency and high-intensity pulsed light in photobioreactors. The model extends the formulation proposed by Zarmi et al. 2020 (https://doi.org/10.1016/j.isci.2020.101115) in order to account for the role of the dark time on photoproduction, photoinhibition effects, and the impact of mixing on cell growth in real photobioreactors. High-frequency pulsed light data from steady state and respirometry experiments are used to calibrate the model, which is demonstrated to shed light on the key photosynthetic mechanisms occurring in these extreme experimental conditions. Furthermore, it is shown how the model can be used to identify optimal operation conditions for microalgae growth, which are confirmed and validated by two respirometry experiments. In particular, it is shown that, for a fixed ratio of the light and dark times, a maximum of productivity can be achieved by minimising the dissipation of photons linked to high light conditions. The result paves the way towards a model-based approach to boost microalgae growth via optimisation of high-frequency high-intensity conditions in artificial light illumination.

Investigation of Criteria for Comparing of Natural and LED Radiation Spectral Distribution

The difference in the spectral composition of artificial and natural lighting can negatively affect health, as well as lead to a distorted perception of the color of surrounding objects. At the same time, a certain correction of the spectral composition of visible radiation in medical institutions and workplaces has a positive effect on human health, while can be carried lighting control out taking into account the data of personal sensor devices that determine the human condition. The purpose of the research was to select criteria for comparing natural and LED optical and visible radiation by spectral composition and by the visibility of color differences in natural and LED lighting. The effectiveness of the application of known and developed criteria for assessing the difference in the spectral composition of optical and visible radiation from natural and LED sources was investigated, as well as for the visibility of color differences in natural and LED lighting. To minimize the values of criteria are proposed additive and subtractive methods for calculating LED parameters. Their comparison allowed us to conclude that a more complex calculation algorithm, but higher performance for an additive technique than for a subtractive one with the same minimization results.It was found that to simulate the spectral composition of natural radiation using LEDs, it is most effective to use the criteria "standard deviations of the relative differences between the optical and visible spectral components of natural and LED radiation". A comparison of the criteria for the visibility of color differences in natural and LED lighting showed approximately the same effectiveness of using the criteria "small color differences" and "standard deviation by photoreceptors" at the present stage and the prospects for applying the second criterion, provided that its acceptable values are established.

Computational Fluid Dynamics Model with Realistic Plant Structures to Study Airflow in and around a Plant Canopy on a Cultivation Shelf in a Plant Factory with Artificial Light

Airflow plays a crucial role in plant growth because it supplies CO2, O2, and energy to plants in a plant factory with artificial light (PFAL). Therefore, understanding how various factors affect airflow in and around a plant canopy is essential. In this study, we developed a computational fluid dynamics (CFD) model with realistic plant structures created using structure-from-motion imaging to investigate airflow in and around a plant canopy. The averages of the absolute percentage errors of simulated air velocity in three conditions were 6.7%, 10.1%, 12.7%, respectively. The simulated and measured air velocities agreed well, confirming the accuracy of the developed CFD model. The effects of inflow velocities and plant canopy structures on the airflow in and around the plant canopy were analysed using the validated CFD model. The inflow velocities significantly decreased stagnant zones (from 62.4% to 7.2%) and increased the airflow uniformity in and around the plant canopy. A staggered layout of the plant canopy slightly decreased stagnant zones (from 16.4% to 13.2%) and increased the airflow uniformity. The airflow in and around the plant canopy was further inhibited by a large plant structure. This CFD model provided a basis for improving the airflow status in and around a plant canopy in a PFAL.

Productivity potential and economic feasibility of small-sized tomato production in plant factories with artificial lighting: A comparative study with high-tech greenhouse production

Plant factories with artificial lighting (PFALs) are hailed as a hope for a sustainable urban food supply system. However, this emerging industry is facing a challenge: What crops other than leafy vegetables can PFALs produce commercially? A promising candidate is small-sized tomatoes (ss-tomatoes), which some high-tech greenhouses (HTGHs) are producing. To examine the crop performance and economic viability of ss-tomato production in PFALs, we attempted a comparative analysis based on experiments conducted in a PFAL and an HTGH, along with a Dutch Report on HTGHs. The results show that ss-tomato production in HTGHs is economically viable in the Netherlands but not yet in our HTGH in Japan. The factor that explains the difference is the yield per plantable area. For our HTGH to be economically viable, the present yield of 30 kg/m2/year must be increased to 50 kg/m2/year. The economic performance of ss-tomato production in our PFAL is lower than that of our HTGH, despite its higher yield of 56 kg/m2/year. To attain the same economic performance, our PFAL must achieve a yield as high as 150 kg/m2/year. If PFALs were to provide a stable supply of safe foods to the growing urban population, they should attain higher yields, no matter how challenging it may be.

Teleworking: does it make workers healthier and productive? A cross-sectional study on a Southern European population

BackgroundTeleworking (TW) has recently shifted from a marginal into a common practice. Yet, concerns have been raised regarding potential work-health negative effects, related to the reduced socialization, and extended working hours with computers at home, possibly offset by reduced commuting time or better individual work-life balance. This paper aims at describing the influence of TW on health, well-being, and productivity perceptions, and how this is shaped by TW conditions.MethodsWe collected data from workers of 25 companies that exert their activity in Portugal. Data were completed with a representative sample of workers who regularly participate in surveys (total N = 1,069). We applied an on-line questionnaire from September the 1st 2022 to December the 1st 2022. We performed a simple descriptive analysis of each variable. Then, we analyzed the relationship between TW conditions and self-reported health, and between TW conditions at home and productivity, using logistic regression models.ResultsWe observed a high prevalence of self-perceived health worsening (15.9%), mostly among those with poor TW conditions. Most teleworkers enjoyed favorable TW conditions, despite limited company support. Relevant changes were observed in lifestyle factors, towards more smoking (5.5%), alcohol drinking (4.5%), and worse diet (10.1%). Two thirds reported enhanced productivity. A statistically significant relationship was observed between inadequate TW conditions, health deterioration, and lower productivity. A 6.0% point (pp) increased risk of productivity worsening was observed when employees faced at least one inadequate condition at home (no private working place at home, inadequate heating, artificial light, or absence of well-being at home). The risk of health deterioration increased by 12.9 pp when facing at least one of these inadequate conditions, and by 6.3 under hybrid TW, compared to one or two days of TW.ConclusionsMost teleworkers highlighted a positive perspective about teleworking. Yet, TW conditions are not favorable for all workers, with consequences on health, well-being, and productivity, suggesting that further support is needed for teleworkers to protect their health at home, and reach its maximum benefit.

Exploring the relationship between office lighting, cognitive performance, and psychophysiological responses: A multidimensional approach

Recognizing the growing importance of optimizing work environments for better cognitive performance, this study examined the relationships between general office lighting, psychophysiological responses and cognitive performance. Sixteen healthy adults in their 20s participated in experiments under nine different lighting conditions combining three levels of correlated color temperature (i.e., 4,000K, 5,000K, and 6,500K) and three levels of illuminance (i.e., 200 lx, 500 lx, and 800 lx). In the experiments, subjects’ primary and complex cognitive performances were measured and their psychophysiological responses such as mental workload, drowsiness, mental fatigue and stress, and visual fatigue were evaluated. Statistical analyses revealed that higher correlated color temperature and illuminance significantly enhanced primary cognitive performance but did not significantly impact complex cognitive performance or most psychophysiological responses. Notably, psychophysiological responses and cognitive performances were found to have mutual relationships rather than one being an absolute independent variable for another. The study suggests that tailored smart lighting systems could enhance cognitive performance in office environments by dynamically adjusting lighting conditions based on real-time psychophysiological feedback.

The Effect of Varying the Light Spectrum of a Scene on the Localisation of Photogrammetric Features

In modern digital photogrammetry, an image is usually registered via a digital matrix with an array of colour filters. From the registration of the image until feature points are detected on the image, the image is subjected to a series of calculations, i.e., demosaicing and conversion to greyscale, among others. These algorithms respond differently to the varying light spectrum of the scene, which consequently results in the feature location changing. In this study, the effect of scene illumination on the localisation of a feature in an image is presented. The demosaicing and greyscale conversion algorithms that produce the largest and smallest deviation of the feature from the reference point were assessed. Twelve different illumination settings from polychromatic light to monochromatic light were developed and performed, and five different demosaicing algorithms and five different methods of converting a colour image to greyscale were analysed. A total of 300 different cases were examined. As the study shows, the lowest deviation in the polychromatic light domain was achieved for light with a colour temperature of 5600 K and 5000 K, while in the monochromatic light domain, it was achieved for light with a green colour. Demosaicing methods have a significant effect on the localisation of a feature, and so the smallest feature deviation was achieved for smooth hue-type demosaicing, while for greyscale conversion, it was achieved for the mean type. Demosaicing and greyscale conversion methods for monochrome light had no effect. The article discusses the problem and concludes with recommendations and suggestions in the area of illuminating the scene with artificial light and the application of the algorithms, in order to achieve the highest accuracy using photogrammetric methods.

An artificial intelligence-assisted system versus white light endoscopy alone for adenoma detection in individuals with Lynch syndrome (TIMELY): an international, multicentre, randomised controlled trial

Computer-aided detection (CADe) systems for colonoscopy have been shown to increase small polyp detection during colonoscopy in the general population. People with Lynch syndrome represent an ideal target population for CADe-assisted colonoscopy because adenomas, the primary cancer precursor lesions, are characterised by their small size and higher likelihood of showing advanced histology. We aimed to evaluate the performance of CADe-assisted colonoscopy in detecting adenomas in individuals with Lynch syndrome. TIMELY was an international, multicentre, parallel, randomised controlled trial done in 11 academic centres and six community centres in Belgium, Germany, Italy, and Spain. We enrolled individuals aged 18 years or older with pathogenic or likely pathogenic MLH1, MSH2, MSH6, or EPCAM variants. Participants were consecutively randomly assigned (1:1) to either CADe (GI Genius) assisted white light endoscopy (WLE) or WLE alone. A centre-stratified randomisation sequence was generated through a computer-generated system with a separate randomisation list for each centre according to block-permuted randomisation (block size 26 patients per centre). Allocation was automatically provided by the online AEG-REDCap database. Participants were masked to the random assignment but endoscopists were not. The primary outcome was the mean number of adenomas per colonoscopy, calculated by dividing the total number of adenomas detected by the total number of colonoscopies and assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT04909671. Between Sept 13, 2021, and April 6, 2023, 456 participants were screened for eligibility, 430 of whom were randomly assigned to receive CADe-assisted colonoscopy (n=214) or WLE (n=216). 256 (60%) participants were female and 174 (40%) were male. In the intention-to-treat analysis, the mean number of adenomas per colonoscopy was 0·64 (SD 1·57) in the CADe group and 0·64 (1·17) in the WLE group (adjusted rate ratio 1·03 [95% CI 0·72-1·47); p=0·87). No adverse events were reported during the trial. In this multicentre international trial, CADe did not improve the detection of adenomas in individuals with Lynch syndrome. High-quality procedures and thorough inspection and exposure of the colonic mucosa remain the cornerstone in surveillance of Lynch syndrome. Spanish Gastroenterology Association, Spanish Society of Digestive Endoscopy, European Society of Gastrointestinal Endoscopy, Societat Catalana de Digestologia, Instituto Carlos III, Beca de la Marato de TV3 2020. Co-funded by the European Union.

Bis-azopyrazole Photoswitches for Efficient Solar Light Harvesting.

Although natural sunlight is one of the most abundant and sustainable energy resources, only a fraction of its energy is currently harnessed and utilized in photoactive systems. The development of molecular photoswitches that can be directly activated by sunlight is imperative for unlocking the full potential of solar energy and addressing the growing energy demands. Herein, we designed a series of 2-amino-1,3-bis-azopyrazoles featuring a coupled πn system, resulting in a pronounced redshift in their spectral absorption, reaching up to 661 nm in the red region. By varying the amino substituents of these molecules, highly efficient E→Z photoisomerization under unfiltered sunlight can be achieved, with yields of up to 88.4 %. Moreover, the Z,Z-isomers have high thermal stability with half-lives from days to years at room temperature. The introduction of ortho-amino substitutions and meta-bisazo units leads to a reversal of the n-π* and πn-π* transitions on the energy scale. This change provides a new perspective for further tuning the visible absorption of azo-switches by utilizing the πn-π* band instead of the conventional n-π* band. These results suggest that photoresponsive systems can be powered by sunlight instead of traditional artificial lights, thereby paving the way for sustainable smart materials and devices.

Bis‐azopyrazole Photoswitches for Efficient Solar Light Harvesting

AbstractAlthough natural sunlight is one of the most abundant and sustainable energy resources, only a fraction of its energy is currently harnessed and utilized in photoactive systems. The development of molecular photoswitches that can be directly activated by sunlight is imperative for unlocking the full potential of solar energy and addressing the growing energy demands. Herein, we designed a series of 2‐amino‐1,3‐bis‐azopyrazoles featuring a coupled πn system, resulting in a pronounced redshift in their spectral absorption, reaching up to 661 nm in the red region. By varying the amino substituents of these molecules, highly efficient E→Z photoisomerization under unfiltered sunlight can be achieved, with yields of up to 88.4 %. Moreover, the Z,Z‐isomers have high thermal stability with half‐lives from days to years at room temperature. The introduction of ortho‐amino substitutions and meta‐bisazo units leads to a reversal of the n–π* and πn–π* transitions on the energy scale. This change provides a new perspective for further tuning the visible absorption of azo‐switches by utilizing the πn–π* band instead of the conventional n–π* band. These results suggest that photoresponsive systems can be powered by sunlight instead of traditional artificial lights, thereby paving the way for sustainable smart materials and devices.

Development of lightweight structural concrete with artificial aggregate manufactured from local clay and solid waste materials

The partial replacement of conventional natural coarse aggregate (NCA) with artificial light weight aggregate (LWA) manufactured from local clay and solid waste to develop a lightweight aggregate concrete (LWAC) for the structural use was studied in this paper. Red clay and Savar clay were used individually with solid wastes like rice husk ash (RHA) and waste glass to produce LWA. The suitability of raw materials and LWA was evaluated by investigating various properties. The mechanical, thermal and durability properties of manufactured LWAC were explored. The results of physical, chemical, thermal and geotechnical properties revealed that Red clay is better than Savar clay for the preparation of LWA. All the physical and mechanical properties of LWA prepared from Red clay are suitable for the preparation of LWAC compared to Savar clay. The test results demonstrated that the concrete manufactured by replacing 30 % of NCA with LWA produced a concrete of lightweight properties. The compressive strength of LWAC for 7 and 28 days was observed as 28 and 48 MPa, respectively. The results of modulus of elasticity, splitting tensile strength, flexural deformation, and creep test of LWAC revealed that these mechanical properties meet the requirements for the structural concrete. The RCP test proves that chlorine permeability of LWAC is comparable with NCA. It was observed that the superior performance of LWAC can be achieved only when the optimized mix designed is followed strictly. The suitability of the replacement of natural aggregate by LWA may be helpful for Bangladesh due to the scarcity of natural coarse aggregate and reusability of solid waste materials.

Development of an operational trap for collection, killing, and preservation of triatomines (Hemiptera: Reduviidae): the kissing bug kill trap.

Surveillance of triatomines or kissing bugs (Hemiptera: Reduviidae: Triatominae), the insect vectors of Trypanosoma cruzi, a Chagas disease agent, is hindered by the lack of an effective trap. To develop a kissing bug trap, we made iterative improvements over 3 years on a basic design resulting in 7 trap prototypes deployed across field sites in Texas, United States and Northern Mexico, yielding the capture of 325 triatomines of 4 species (Triatoma gerstaeckeri [Stål], T. sanguisuga [LeConte], T. neotomae [Neiva], and T. rubida [Uhler]). We began in 2019 with vertical transparent tarpaulin panel traps illuminated with artificial light powered by AC current, which were successful in autonomous trapping of flying triatomines, but were expensive, labor-intensive, and fragile. In 2020, we switched to white LED lights powered by a solar cell. We tested a scaled-down version of the vertical panel traps, a commercial cross-vane trap, and a multiple-funnel trap. The multiple-funnel traps captured 2.6× more kissing bugs per trap-day than cross-vane traps and approached the performance of the vertical panel traps in number of triatomines captured, number of triatomines per trap-day and triatomines per arthropod bycatch. Multiple-funnel traps required the least labor, were more durable, and had the highest triatomines per day per cost. Propylene glycol in the collection cups effectively preserved captured triatomines allowing for molecular detection of T. cruzi. The trapping experiments established dispersal patterns for the captured species. We conclude that multiple-funnel traps with solar-powered LED lights should be considered for adoption as surveillance and potentially mass-trapping management tools for triatomines.

Research on Thermal Environment of Container Farms: Key Factor Identification and Priority Analysis

Container farms (CFs), a controlled environment agricultural technology designed to solve food insecurity, are receiving increasing attention from researchers. However, the complex geometric structures and artificial lighting used in CFs present challenges in effectively controlling the thermal environment. This study aims to identify the primary factors that impact the thermal environment of CFs while conducting factor ranking and significance analysis, providing a theoretical basis for future thermal environment optimization. The research method of theoretical analysis, CFD simulation, and an orthogonal experimental design were adopted to achieve the above objectives. Theoretical analysis revealed that factors influencing the thermal environment are the HVAC system’s supply air temperature, humidity, flow rate, and the light source used. Four evaluation indices, including the mean value and range between layers of temperature and moisture content, were used. The results revealed that supply air temperature and light source are significant for mean temperature, while supply air temperature and humidity are significant for mean moisture content. In the case of range between layers, supply air flow rate and light source display a significant correlation. These findings suggest that future optimization should prioritize the regulation of the HVAC system’s supply air and light source.

Relative importance of intensity and spectrum of artificial light at night in disrupting behavior of a nocturnal rodent.

The influence of light spectral properties on circadian rhythms is of substantial interest to laboratory-based investigation of the circadian system and to field-based understanding of the effects of artificial light at night. The trade-offs between intensity and spectrum regarding masking behaviors are largely unknown, even for well-studied organisms. We used a custom LED illumination system to document the response of wild-type house mice (Mus musculus) to 1-h nocturnal exposure of all combinations of four intensity levels (0.01, 0.5, 5 and 50 lx) and three correlated color temperatures (CCT; 1750, 1950 and 3000 K). Higher intensities of light (50 lx) suppressed cage activity substantially, and consistently more for the higher CCT light (91% for 3000 K, 53% for 1750 K). At the lowest intensity (0.01 lx), mean activity was increased, with the greatest increases for the lowest CCT (12.3% increase at 1750 K, 3% increase at 3000 K). Multiple linear regression confirmed the influence of both CCT and intensity on changes in activity, with the scaled effect size of intensity 3.6 times greater than that of CCT. Activity suppression was significantly lower for male than for female mice. Assessment of light-evoked cFos expression in the suprachiasmatic nucleus at 50 lx showed no significant difference between high and low CCT exposure. The significant differences by spectral composition illustrate a need to account for light spectrum in circadian studies of behavior, and confirm that spectral controls can mitigate some, but certainly not all, of the effects of light pollution on species in the wild.

Balancing the Energy Efficiency Benefits of Glazed Surfaces: A Case Study

Daylighting design is not only dimensioning glazed surfaces to provide sufficient natural light to an occupied space but also a method of analyzing how this can be achieved without unwanted effects, such as gains and losses of heat, glare, and variations in daylighting intensity at various indoor distances and levels. The case study presented in this paper highlights the energy consumed due to a group of windows with a large glazed area in an existing building located in a temperate continental climate area. The energy consumption results from supplementary artificial lighting required to maintain adequate illumination for indoor activities and to counterbalance heat loss during colder periods are evaluated. The analysis performed by modifying the glazed surface led to the identification of an optimum value of window dimensions for minimum energy consumption. The results of the case study highlight the fact that the evolution of the total energy consumption, evaluated as the sum of the energy consumption due to additional heating/cooling and the artificial lighting required to compensate for the reduction in natural light, is strongly influenced by the dimensions of the glazed surfaces, as well as the minimum level of lighting imposed by the regime of activities carried out in the building. Thus, the outcomes obtained in the research show that at lighting values below 500 lx, the total energy consumption is directly proportional to the glazed surface. From values of 500 lx for the illuminance level, the total energy consumption drops from 2730 kWh/year for a window height of 230 cm to 2399 kWh/year for a height of 110 cm, after which it starts to rise again, reaching a value of 2786 kWh/year for a height of 30 cm. This phenomenon is also found at values higher than 500 lx; accordingly, for an imposed lighting of 1000 lx, the minimum total consumption is identified at a window height of 150 cm. The case study presented in this paper clearly highlights a complex relationship between the height of the glazed surface and the energy consumption required to compensate for heating or cooling and the reduction in natural lighting. Lower window heights reduce heat loss or gain but also correspondingly increase the energy consumption of artificial lighting.

Influence of Temperature and LED Light Spectra on Flavonoid Contents in Poa pratensis

Light and temperature are the driving forces in plant development and growth. Specific photoreceptors provide the ability to sense and interpret light and temperature to regulate growth. Under the limited light conditions in most sports stadiums, natural grasses suffer from light deficiency. Artificial light provided by light-emitting diodes (LEDs) is used to increase their growth and adjust their development. Flavonoids like flavonols and anthocyanins are influenced by light conditions and temperature. Increased blue light can elevate the content of these secondary metabolites. Remote measurements of internal parameters using non-destructive methods provided information on their content under different temperature conditions for quality monitoring. This experiment tested flavonoid contents in Kentucky bluegrass (Poa pratensis) for different blue-to-red light ratios (0.6 and 0.4) and three temperature courses (constant temperature of 4 °C, constant temperature of 12 °C, and temperature switching among 12–8–4–8–12 °C). The results show elevated levels of flavonoids under blue-dominant artificial light as well as increased content under low-temperature (4 °C) conditions. The lack of flavonoids at elevated temperatures (12 °C), especially under red-dominant light, suggests an increased requirement for artificial blue light at increased temperatures. Non-destructive flavonoid determination was suitable for this experiment and can therefore be used for practical sports turf quality monitoring.

Degradation of bromothymol blue and methyl green from aqueous media by Photo-Fenton: comparison between UV-lamp and sun irradiation

Abstract The degradation of two textile dye molecules was studied using photochemical processes, both in the absence and presence of light. Various methods were employed, including photolysis/UV, combined H2O2/UV photolysis, Fe2+/UV treatment, Photo-Fenton/UV at 350 nm and Photo-Fenton with solar irradiation. The decolorization efficiency of dyes in aqueous solution was evaluated for two specific dyes: Bromothymol Blue (BTB) and Methyl Green (MG). These experiments were carried out in batch mode. The results demonstrated a synergy between light irradiation and the presence of Fenton’s reagents, such as hydrogen peroxide and divalent iron. In addition, it was demonstrated that direct solar irradiation can be used without specific devices to achieve high efficiency at low cost. In the first part, we checked the impact of the various operating parameters. Reaction efficiencies were compared for the same system in the dark and under the assistance of an artificial or solar light source. In the second part, we studied the parameters of the Photo-Fenton process, such as the initial pH of the solution, the initial concentrations of oxidant, iron catalyst, and dye under irradiation from either light source. Whereas the mere photolysis without Fenton’s reagents allowed decolorization yields below 26 %, addition of the oxidant (H2O2) or the catalyst (Fe(II) species amplified the treatment efficiency. However, the presence of both H2O2 and Fe(II) under light irradiation was shown synergetic with yields ranging from 72 to 85 % depending on the dye worked and the light source: because of its broader spectrum in the UV domain, solar irradiation led to the highest decolorization yields. The above results were obtained for well-defined proportions of dye and reagents: for a 20 mg/l dye solution, Fe(II) catalyst concentration equal to 10−3 M, peroxide concentration of 5.10−2 M and a pH of 3. These conditions allowed optimal production of OH· radicals, allowing high efficiency in systems using solar irradiation.

Synthesis and Characterization of ZnO and TiO2 Hybrid Coatings for Textile UV Anti-Aging Protection.

The aim of this study was to prepare and characterize thin hybrid films on polyurethane-coated knitted fabrics and to achieve satisfactory color fastness to artificial light. Sol-gel-derived hybrid thin films were deposited via the dip-coating of 3-glycidoxypropiltrimethoxysilane. Titanium dioxide (TiO2) and zinc oxide (ZnO) nanopowders were added to compensate for the insufficient aging resistance, which manifests itself in low color fastness and is one of the most frequent complaints from manufacturers of coated marine fabrics (yachts, boats, etc.). The optimum processing conditions were determined by varying the concentration of precursors and auxiliaries, the mass concentration of TiO2 and ZnO nanopowders, the drawing speed, and the methods and process of fabric treatment. The hybrid films were also characterized using scanning electron microscopy and Fourier transform infrared spectroscopy with attenuated total internal reflection, while Spectraflash SF 300 investigated color fastness. After 300 h of exposure in a xenon chamber, the thin hybrid films showed good color fastness and good resistance to washing cycles. The sol-gel treatment proved to be a successful answer to the manufacturers' need for the post-treatment of polyurethane-coated knitted fabrics against UV radiation for use in the marine sector (yachts, speedboats, etc.).

Does the Daily Light Integral Influence the Sowing Density of Tomato Plug Seedlings in a Controlled Environment?

To achieve high-density tomato seedlings in a plant factory with artificial lighting, tomatoes (Solanum lycopersicum Mill. cv. “Zhongza NO.9”) were used as the experimental material. This study expected to analyze the effects of light intensity (150, 200, 250, and 300 μmol·m−2·s−1) and light time (12 and 14 h), as well as daily light integral (DLI, 10.80, 12.60, and 12.96 mol·m−2·d−1) and sowing density (50, 72, and 105 holes per tray), on seedling quality. The results indicated that biomass accumulation, seedling quality, and energy use efficiency of seedlings significantly improved with an increase in DLI. At a DLI of 12.96 mol·m−2·d−1, seedlings sown at a density of 72 holes per tray exhibited comparable growth characteristics and biomass accumulation to those sown at 50 holes per tray. However, under lower DLIs, seedlings at 50 holes per tray displayed superior growth morphology and seedling quality compared to those at 72 holes per tray. This indicates that increasing the DLI can partially mitigate the negative effects of higher sowing density on seedling quality. Light use efficiency (LUE) and energy use efficiency (EUE) were not significantly different between seedlings at 72 and 105 holes per tray but were higher than those at 50 holes per tray. Therefore, optimizing parameters such as DLI and sowing density can effectively enhance the seedling quality, spatial use efficiency, and light use efficiency in industrial seedling production. Based on the results of this study, a DLI of 12.96 mol·m−2·d−1 (achieved with a light intensity of 300 μmol·m−2·s−1 and a light time of 12 h) and sowing density of 72 holes per tray are recommended for cultivating high-quality tomato seedlings while reducing energy consumption.

Underwater light source changes nitrogen and phosphorus removal pathways by Vallisneria spinulosa Yan growth system

Vallisneria spinulosa Yan (V.spinulosa Yan) with good ability of water purification is often used for ecological restoration of polluted water bodies. However, it is difficult to survive in turbid water bodies due to the low lighting condition. This study explored the feasibility of introducing artificial underwater light source into water bodies with high turbidity to strengthen the water restoration by V.spinulosa Yan. Addition of underwater light source promoted the clonal reproduction ability of V.spinulosa Yan, thus enhancing the removal loads of total nitrogen (TN), total phosphorus (TP), and nitrate nitrogen (NO3−-N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathrm{NO}}^{-}_{3}{\\mbox{-}}{\\mathrm{N}}$$\\end{document}) by 1.60–3.43 × 10−2, 1.49–3.49 × 10−3, and 0.80–2.06 × 10−2 g m−2 d−1, respectively. Underwater light source significantly reduced the abundance of microbial community on V.spinulosa Yan leaves, as well as most nitrifying bacteria (Nitrosomonadaceae) and denitrifying bacteria (Nitrospira, Comamonadaceae, and Rhodocyclaceae) in the system. But the attachment of some Cyanophyta (Chloroplast and Cyanobacteria) and Photosynthetic bacteria (Rhodobacter) onto the leaves and the growth of Methyloligellaceae in water and sediments were promoted. Nitrogen and phosphorus removal by the growth system of V.spinulosa Yan without underwater light source mainly depended on the biological processes by functional bacteria, while the absorption and co-assimilation effect of V.spinulosa Yan with underwater light source.