Mean Light Intensity Research Articles

High cell density culture of microalgae in horizontal thin-layer algal reactor: Modeling of light attenuation and cell growth kinetics

This study delved into the light intensity effects and light attenuation modeling in high cell density culture (HCDC) of green alga Neochloris oleoabundans. The research primarily focused on how different light intensities influence cell growth in terms of cell division and cell mass, and the biochemical composition within the cells. Recognizing the need to avoid overestimating light path by excluding data point in the data zone where the light intensity was zero, we proposed and verified a novel modified Beer-Lambert model, which was superb in fitting experimental data and predicting light attenuation in both low and high cell density cultures. Taking advantage of the prediction power of the modified Beer-Lambert model, we devised an approach to maintain constant mean light intensity (Imean) and by adjusting the incident light intensity (I0). The results indicate that at an Imean of approximately 66.67 μmol/m2/s and 6 mm culture thickness, maximum volumetric and areal biomass productivities of 2.72 g/L/day and 16.32 g/m2/day, respectively, were achieved. Whereas the highest biomass concentration of 28.20 g/L was produced in 20 days at Imean 50 μmol/m2/s. Photoinhibition to cell division become evident at I0 750 μmol/m2/s and above. Using the data generated at constant Imean in the constant specific growth rate range, superb fitting to the Monod model with a R2 of 0.9910 was demonstrated, highlighting the importance of generating reliable data for the modelling of the kinetics of photoautotrophic growth of microalgae, which had considered to be challenging.

Effect of fortnightly and seasonal changes in estuarine physical variables on phytoplankton distribution in a macrotidal monsoon estuary

Seasonal and neap-spring tidal changes in estuarine physical variables and their effect on the phytoplankton distribution in the macrotidal Tanintharyi River estuary (TRE), Myanmar were studied in 2019. During the dry season, the saltwater intrudes upstream while only until the mid-estuary during the wet season due to the hindering of saltwater by the strong river flow. The turbidity variations driven by enhanced mixing and neap-spring transition influenced the light required for phytoplankton growth during both seasons. The diversity index was higher (2.57–3.07) in the dry season with low evenness (0.64–0.79) compared to the low diversity index (2.16–2.73) with high evenness (0.75–0.90) in the wet season. The peak diatom density was observed under low turbidity (6 FTU) and a salinity of 25, and their distribution were correlated positively with salinity, mean light intensity in the mixed layer (Im) and euphotic depth (Ze) while negatively with light attenuation (K) and turbidity. Among diatoms species, Thalassionema frauenfeldii, Thalassionema nitzschioides and Pseudonitzschia seriata were found as dominant species (positively correlated with salinity and Im whereas negatively with turbidity and K) during the dry season whereas Thalassiosira eccentrica and Coscinodiscus granii were dominant with low salinity in the wet season. The dinoflagellates were more sensitive to strong mixing condition than diatoms and their distribution were positively influenced by Im and Ze. Therefore, the neap-spring tidal and seasonal variations in saltwater intrusion, mixing, turbidity, and light availability are the major factors that maintained the phytoplankton diversity in the tropical TRE.

Daily light exposure profiles and the association with objective sleep quality in patients with Parkinson's disease: The PHASE study.

Light information crucially influences sleep initiation and continuity. The purpose of this study was to compare daily light exposure between patients with Parkinson's disease (PD) and non-PD older adults and evaluate the association of daily light exposure with objective sleep measures in patients with PD. In this cross-sectional study of 189 outpatients with PD and 1101 community-dwelling older adults (controls), daily light exposure was measured using wrist light meters during the daytime and light meters set in the bedrooms during the nighttime, and objective sleep quality was measured by wrist actigraphy. The median duration of exposure to ≥ 1000 lux light was significantly shorter in patients with PD than in controls. The median nighttime light intensity was higher in patients with PD than in controls. Among patients with PD, multivariable analysis suggested that the highest quartile of exposure to ≥ 1000 lux light during the daytime was linked to significantly higher sleep efficiency (SE) by 8.0% and shorter wake after sleep onset (WASO) by 36.9 minutes than the lowest quartile. During the nighttime, the highest quartile of mean light intensity had significantly lower SE by 6.8%, longer WASO by 24.1 minutes, longer sleep onset latency, and higher fragmentation index, than the lowest quartile. Importantly, daytime and nighttime light levels were independently associated with objective sleep measures. The present study illustrated that greater daytime light exposure and lower nighttime light exposure are significantly associated with better objective sleep measures in patients with PD.

Effect of mount location on the quantification of light intensity in myopia study

PurposeTo investigate how the mounting location of wearable devices affects the measurement of light intensity.MethodsTwo commercially available wearable devices, HOBO and Clouclip, were used to compare the effects of different...

Evaluating Underwater Light Availability for Phytoplankton: Mean Light Intensity in the Mixed Layer versus Attenuation Coefficient

The use of several light-related variables, such as the Secchi disc depth, the euphotic depth, and in particular, the diffuse attenuation coefficient (Kd), is deeply rooted in phytoplankton research, but these are not the most appropriate indicators of the amount of light available for photosynthesis. We argue that the variable of interest for phytoplankton is the mean light intensity in the mixed layer (Im), which represents the mean light to which phytoplankton cells are exposed throughout their life cycle, while being continuously mixed in the mixed layer. We use empirical data collected in different coastal ecosystems in southern Portugal to demonstrate why Im should be the preferred metric instead of the deeply rooted Kd. We show that, although the relationship between Im and Kd is inversely proportional, it is not always strong or even significant. Different Im values can be associated with the same Kd, but distinct Im have different physiological effects of phytoplankton. Therefore, Kd does not capture the amount of light available for photosynthesis, given that, unlike Im, Kd calculation does not consider the depth of the mixed layer. Therefore, we urge phytoplankton researchers to consider the measurement and calculation of Im when evaluating light-related processes in phytoplankton ecology.

Growth comparison of Arthrospira platensis in different vessels: standard cylinder vs. enhanced surface area at low light

ABSTRACT A laboratory scale prototype of a novel tube called AlgaTube™ (patent pending) was evaluated for growth of Arthrospira platensis (commonly referred to as Spirulina) in a controlled, 10-day batch trial at low light intensity. The two cultures (control and prototype) were grown in identical conditions inside a closed incubator space at 32°C with a mean light intensity of 55 µmol photons m−2 s−1 LED light, consisting mostly of red and blue wavelengths with some full spectrum background radiation. OD590 was measured daily and converted to Concentration (Cd, g l−1) using a standard curve. Four independent replicates of the trial were run. Six biomass growth metrics were evaluated and compared. Across the board, all six growth metrics showed higher rates of biomass growth in the AlgaTube™. Maximum concentration was 34% higher (p = 0.02), cumulative production was 41% higher (p = 0.02), specific growth rate was 17% higher (p = 0.02), maximum specific growth rate was 23% higher (p = 0.02), mean daily production was 41% higher (p = 0.001), and maximum daily production was 38% higher (p = 0.19). We conclude that the novel shape of the AlgaTube™ prototype increased biomass growth rates. We believe that this study constitutes successful proof-of-concept for the AlgaTube™, but further studies are needed to optimize its performance.

Light intensity measurement using LabVIEW graphical programming environment

Abstract Lighting and light distribution have a crucial influence on factors such as performance and occupational safety. This paper aims to create a virtual instrument (VI), developed around the Arduino Uno development platform, designed to measure the light intensity using the BPW34 sensitive silicon PIN photodiode. The reverse-biased photodiode can be used as a light detector by monitoring the current flowing through it. Coupled to a 10Kohm resistor and considering the specifications of the BPW34 model, a simple relationship is offered between lux (light intensity) and the voltage across the resistance. The virtual instrument reads this voltage and converts it to a light intensity value in Lux. There is also an alarming function if the light intensity exceeds the set value. The VI also shows basic statistics like Max, Mean, and Min light intensity values.

Cover Feature: Resonances at Fundamental and Harmonic Frequencies for Selective Imaging of Sine‐Wave Illuminated Reversibly Photoactivatable Labels (ChemPhysChem 23/2022)

The Cover Feature shows the principle of HIGHLIGHT, a simple and general strategy to selectively image a reversibly photoactivatable fluorescent label associated with given kinetics. HIGHLIGHT uses specific frequencies and mean light intensities (I1, I2) associated with resonances of the amplitudes of concentration or fluorescence oscillations at harmonic frequencies to generate a set of non-redundant resonant observables (S) that are recovered simultaneously from a single experiment. More information can be found in the Research Article by Annie Lemarchand, Vincent Croquette, Ludovic Jullien, Thomas Le Saux and co-workers.

Light intensity and uniformity in commercial broiler houses using lighting programs derived from Global Animal Partnership (GAP) lighting standards

Global Animal Partnership (GAP) is an organization that has created alternative standards for raising commercial broilers, including elevated light intensity and provisions for natural light. The objectives of this study were to compare light intensity levels and spatial uniformity in the following treatments derived from GAP lighting standards: 1) light intensity from natural and artificial sources greater than 50 lx (NL 1% +LED), and 2) natural light only provided through an opening equal or greater than 1.0% of total floor area (NL 1% ). Light intensity was also measured in a house using a traditional LED lighting program (LED) for comparison. Light intensity was spatially measured at a fixed point in time (static) for the NL 1% +LED, NL 1% , and LED treatments and then temporally measured in three house sections (pad, mid, and fan) over a 24 h period. Overall static mean light intensity was significantly higher (P < 0.05) in the NL 1% +LED and NL 1% treatments than the LED treatment, and most dissimilar in the mid house section (LED=2.8 lx, NL 1% +LED=95.4 lx, NL 1% =77.1 lx). Seventy-nine percent and 53% of the floor area in the NL 1% +LED and NL 1% treatments were above 50 lx, the target light intensity set by GAP. Light uniformity was best in the pad and mid sections of the LED treatment. Temporal testing showed at mid house that light intensity was most influenced by natural light and that daily averages were 23 times higher in the NL 1% treatment (NL 1% =46.0 lx; LED = 2.0 lx). GAP derived lighting programs resulted in markedly different lighting environments compared to traditional programs.

Resonances at Fundamental and Harmonic Frequencies for Selective Imaging of Sine-Wave Illuminated Reversibly Photoactivatable Labels.

We introduce HIGHLIGHT as a simple and general strategy to selectively image a reversibly photoactivatable fluorescent label associated with a given kinetics. The label is submitted to sine-wave illumination of large amplitude, which generates oscillations of its concentration and fluorescence at higher harmonic frequencies. For singularizing a label, HIGHLIGHT uses specific frequencies and mean light intensities associated with resonances of the amplitudes of concentration and fluorescence oscillations at harmonic frequencies. Several non-redundant resonant observables are simultaneously retrieved from a single experiment with phase-sensitive detection. HIGHLIGHT is used for selective imaging of four spectrally similar fluorescent proteins that had not been discriminated so far. Moreover, labels out of targeted locations can be discarded in an inhomogeneous spatial profile of illumination. HIGHLIGHT opens roads for simplified optical setups at reduced cost and easier maintenance.

Barrier effect against Bemisia tabaci and the control of tomato yellow leaf curl virus in a tomato-maize intercropping system

We examined the barrier effects against Bemisia tabaci and the potential to control the tomato yellow leaf curl virus (TYLCV) of different tomato-maize intercropping modes. Tomatoes (variety Jinshan 511) were planted at a fixed row distance either as a monoculture or together with maize (variety Xianyu 335) at the distances of 10, 20, and 30 cm. We investigated the viral index for TYLCV and the population density of B. tabaci. Compared with tomato monoculture, the natural barrier established by the maize stabilized the growth environment for tomato. When the maize spacing was 10, 20, and 30 cm, the average temperature of tomato plants from 6:00 to 20:00 decreased by 3.01, 2.26, and 1.45 ℃, the average relative humidity increased by 13.0%, 8.8%, and 6.0%, and the mean light intensity reduced by 26.1%, 20.4%, and 14.5%, respectively. The changes of those factors alleviated the adverse environmental conditions (i.e., intense light, high temperature, and lack of moisture) that promote the spread of virus-related diseases during the high-temperature period of the day, with the most effective planting distance for the maize being 10 cm. Our results suggested that the intercropping of tomato and maize had a barrier effect against B. tabaci and was able to control the TYLCV in tomato. When the planting distance for the maize was 10, 20, and 30 cm, the number of B. tabaci was 88.7%, 82.0%, and 73.9% lower than tomato monoculture, respectively. The TYLCV was inhibited, with the viral disease index being decreased by 67.3%, 59.4%, and 44.5%, respectively. Tomato-maize intercropping was also beneficial for tomato plant growth and fruit set, which could enhance tomato yield. Such effect was strengthened under higher maize density.

Light Intensity in Nursery Schools: A Possible Factor in Refractive Development.

Increased levels of outdoor light have been found to be associated causally with decreased rates of myopia. The goal of this study was to measure the effect of indoor nursery school light intensity on refraction of preschool children in Israel. A total of 1596 children aged 4 to 5 years from 27 nursery schools were examined. Light intensity was tested with a luxmeter device (Lux) inside and outside the nursery school. Noncycloplegic refractions were measured with the PlusOptix vision A09 screening device. Data analysis was performed using Pearson coefficients, chi-square tests for proportions and ANOVA tests by tertiles of illuminance. This study included 1131 kindergarten children with a mean age of 4.87 ± 0.33 years, of which 571 were female (50.5%). The mean light intensity of the low, medium, and high intensity groups differed significantly (ANOVA P < 0.001) at 359 ± 2.64 lux (range 264-431), 490 ± 2.21 lux (range 432-574), and 670.76 ± 3.73 lux (range 578-804), respectively. Mean spherical equivalent (SE) was +0.56 ± 0.03D for the low-intensity group, +0.73 ± 0.03D for the medium-intensity group, and +0.89 ± 0.03D for the high-intensity group (ANOVA P < 0.001). The low-intensity group had 42.1% of children with zero refraction or less, while the high-intensity group had 19.3%. In the nursery schools, lower amounts of illumination were associated with less hyperopic refractive error. As the low hyperopic reserve is a risk factor for developing myopia, this finding needs to be followed up to establish whether this association reflects a causal relationship, which could be modulated for the prevention of myopia.

Simple and rapid method for selective enumeration of lactic acid bacteria in commercially prepared yogurt by image analysis and K-means clustering.

We developed a simple and rapid method based on the combination of image analysis and k-means clustering to selectively enumerate cocci and bacilli from among lactic acid bacteria (LAB) in commercially prepared yogurt. We used our previously reported method for recovering only LAB without non-microbial substances from commercial yogurt, and found that the shape and light intensity of LAB cell images taken by optical microscopy were factors that could distinguish cocci and bacilli, allowing the selective enumeration of LAB. Also, k-means clustering was executed on a dataset of the mean light intensity and aspect ratio of each LAB obtained by image analysis, and each LAB in the image could be automatically assigned to either the cocci or bacilli group. The results obtained by this automated method were in good agreement with those obtained by manually counting the LAB under a microscope, with an overall error within 10%. In addition, this method could provide results within a few hours, which is approximately 1/32 of the time required for the conventional colony-counting method.

Effects of Light-Curing Techniques on Dental Resins - A Cross-Sectional Study

Background: Commonly used dental resin composites are used as dental filling materials with the help of light induced polymerization reaction. The purpose of this cross-sectional research was to compare the results of different light intensities on the hardness of different dental composites. Following light treatment units were used.&#x0D; &#x0D; QTH also called Quartz Tungsten Halogen&#x0D; LED also called Light Emitting Diodes&#x0D; &#x0D; Methods: This one-month cross-sectional, in-vitro study was carried out in the Dental Materials Laboratory in Saudi Arabia. Using non-probability, convenient sampling, a single trained operator prepared 60 dental restorative composites (DRC) samples in steel molds with a diameter of 10mm and each mold was 2mm thick. During the polymerization of DRCs, the effects of light intensities, sorption and solubility, and microhardness were all measured. SPSS was used for statistical analysis and a p-value of &lt;0.05 was declared striking.&#x0D; Results: When QTH and LED lamps were used, the average micro hardness of DRC was estimated to be 15.480.46 and 18.260.53, respectively. The mean light intensity of QTH was 434 mW/cm2 and for LED lights it was 925mW/cm2. There was no notable difference in DRC sorption and solubility capability (p=0.001) during the polymerization reaction (p=0.128).&#x0D; Conclusion: When it came to increasing the surface micro hardness of DRC, LED light was found to be more effective than QTH light.

Does Photomineralization of Dissolved Organics Matter in Temperate Rivers?

AbstractSunlight can oxidize dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) in freshwaters. The importance of complete photooxidation, or photomineralization, as a sink for DOC remains unclear in temperate rivers, as most estimates are restricted to lakes, high latitude rivers, and coastal river plumes. In this study, we construct a model representing over 75,000 river reaches in the Connecticut River Watershed (CRW), USA, to calculate spectrally resolved photomineralization. We test the hypothesis that photomineralization is a negligible DOC sink across all reaches and flow conditions relative to DOC fluxes. Our model quantifies reaction rates and transport drivers within the river reaches for the ranges of flow conditions, incoming solar irradiance, and canopy cover shading observed throughout the year. Our model predicts average daily areal photomineralization rates ranging from 1.16 mg‐C m−2 day−1 in low flow river reaches in the winter, to 18.33 mg‐C m−2 day−1 in high flow river reaches during the summer. Even for high photomineralization fluxes, corresponding photomineralization uptake velocities are typically at least an order of magnitude smaller than those reported for other instream processes. We calculate DOC elimination by photomineralization relative to DOC fluxes through individual stream reaches as well as the entire riverine portion of the CRW. We find that relative photomineralization fluxes are highest in summer drought conditions in low order streams. In median flows and mean light intensities, for an average watershed travel distance, 3%–5% of the DOC fluxes are eliminated, indicating that photomineralization is a minor DOC sink in temperate rivers.

Comparative Effectiveness of Two Light Curing Units on the Properties of Dental Resin Composites

Background: Setting of conventional glass ionomers cement and dental resin composites as filling materials is predominantly through polymerization reaction, which is usually induced by light. The objective of this study was to assess the temperature changes, light intensities, sorption and solubility capability and comparative micro hardness in Dental Resin Composites (DRC) by using two different light curing units that is Quartz Tungsten Halogen (QTH) and Light Emitting Diodes (LED). Methods: This analytical, experimental, in-vitro study was spanned over one month, conducted in the laboratory of Dental Materials, Dr. Ishrat-ul-Ibad Khan Institute of Oral Health Sciences. Through non-probability, convenient sampling, 60 samples of DRCs was prepared as 10mm in diameter and 2mm in thickness in the steel moulds by a single trained operator. Effect of heat generation, light intensities, sorption and solubility and micro hardness during polymerization of DRCs were all measured. Statistical analysis was done using SPSS with descriptive statistics and two sample independent t-tests. The p-value of &lt;0.05 was considered significant at 95 % confidence level. Results: Mean surface micro hardness of DRC was found to be 15.48±0.46 and 18.26±0.53 when QTH and LED lamps were employed respectively. Whereas, mean light intensity of QTH and LED lamps were found to be 434 and 925mW/cm2. No significant difference in temperature change during polymerization reaction (p=0.128) and in sorption and solubility capability (p=0.001) of DRC was observed. Conclusion: Light-emitting diodes were evaluated to be more effective than Quartz Tungsten Halogen Light in achieving increased surface micro hardness of DRC. Keywords: Light; Glass Ionomer Cements; Tungsten; Hardness.

Seasonal variations in phytoplankton productivity in a shallow cove in the eastern Seto Inland Sea, Japan

We examined phytoplankton productivity in Shido Bay, an active oyster farming area in the eastern Seto Inland Sea, Japan, by an in situ 13C method from March 2016 to January 2017. The depth-integrated daily phytoplankton production ranged from 0.13 to 1.61 g C m−2 day−1, and the estimated annual production was 218 g C m−2 year−1. The daily production peaked in the rainy season and autumn, when phytoplankton blooms were observed, and production during the bloom events largely contributed to the annual production. There was a strong correlation between daily production and phytoplankton biomass (chlorophyll a) throughout the study period. In the study area, due to the shallow depth (6 m) and moderate light attenuation coefficient of the water column (0.38 ± 0.07 m−1), the mean light intensity in the water column was maintained at high levels (36 ± 5% of incident photosynthetically active radiation) throughout the study period. In contrast, the dissolved inorganic nitrogen concentration of the water was persistently low (< 1.5 µM) from late winter to summer. As a consequence, an increase in nitrogen supply seemed to be the key factor causing the increases in daily production and directly triggering the phytoplankton blooms in the bay.

Efficacy of 3D digital visualization in minimizing coaxial illumination and phototoxic potential in cataract surgery: pilot study.

To compare the coaxial light intensity required during cataract surgery and rate of postoperative visual recovery, with surgical visualization achieved with a traditional analog operating microscope compared with a 3D digital visualization system. Weill Cornell Medical Center, New York Presbyterian Hospital, New York, New York. Retrospective, consecutive, single-surgeon series. Patients undergoing femtosecond laser-assisted cataract surgery were retrospectively grouped into either: (1) visualization using the binoculars of a standard operating microscope (traditional group) or (2) visualization using a 3D digital visualization system affixed to the same operating microscope (digital group). Note was made in each case of light intensity used, light exposure time, intraoperative and/or postoperative complications, and postoperative visual acuities. The study comprised 24 eyes in the traditional group and 27 eyes in the digital group. There were no intraoperative or postoperative complications in either group and no difference in mean light exposure time, but the mean light intensity used in the digital group was significantly less (18.5% ± 1.5%) than that in the traditional group (43.3% ± 3.7%; P < .001). Furthermore, the digital group achieved a postoperative day 1 visual acuity that was within 2 lines of the postoperative month 1 visual acuity a greater percentage of time than that in the traditional group (81.5% of eyes vs 54.2% of eyes; P = .04). Light intensity was significantly decreased in patients who underwent cataract surgery assisted by the 3D digital visualization platform without an increase in complications or surgical time and possibly with a faster postoperative visual recovery.

Moving in the Dark-Evidence for an Influence of Artificial Light at Night on the Movement Behaviour of European Hedgehogs (Erinaceus europaeus).

Simple SummaryThe European hedgehog is one of the most popular and well-known wild animals, but its numbers are declining throughout Europe, especially in rural areas. Effective hedgehog conservation requires an understanding of the hedgehog’s ability to adapt to a changing environment. Due to globally increasing urbanisation, the use of artificial light sources to illuminate the night, called light pollution, has spread dramatically. Light pollution significantly affects the behaviour and ecology of wildlife, but the hedgehog’s behaviour towards light pollution remains unknown. We therefore investigated the effects of light pollution on the natural movement behaviour of hedgehogs living in an urban environment. Although hedgehogs can react very variably to environmental influences, the majority of hedgehogs studied here preferred to move in less illuminated rather than in strongly illuminated areas. This apparently rigid behaviour could be used in applied hedgehog conservation to connect isolated hedgehog populations or to safely guide the animals around places dangerous for them via dark corridors that are attractive for hedgehogs.With urban areas growing worldwide comes an increase in artificial light at night (ALAN), causing a significant impact on wildlife behaviour and its ecological relationships. The effects of ALAN on nocturnal and protected European hedgehogs (Erinaceus europaeus) are unknown but their identification is important for sustainable species conservation and management. In a pilot study, we investigated the influence of ALAN on the natural movement behaviour of 22 hedgehogs (nine females, 13 males) in urban environments. Over the course of four years, we equipped hedgehogs at three different study locations in Berlin with biologgers to record their behaviour for several weeks. We used Global Positioning System (GPS) tags to monitor their spatial behaviour, very high-frequency (VHF) loggers to locate their nests during daytime, and accelerometers to distinguish between active and passive behaviours. We compared the mean light intensity of the locations recorded when the hedgehogs were active with the mean light intensity of simulated locations randomly distributed in the individual’s home range. We were able to show that the ALAN intensity of the hedgehogs’ habitations was significantly lower compared to the simulated values, regardless of the animal’s sex. This ALAN-related avoidance in the movement behaviour can be used for applied hedgehog conservation.

Influence of Medium Frequency Light/Dark Cycles on the Cultivation of Auxenochlorella pyrenoidosa

Light (wavelength, intensity, and light/dark cycle) have been considered as one of the most important parameters for microalgae cultivation. In this paper, the effect of medium frequency intermittent light on Auxenochlorella pyrenoidosa (formerly Chlorella pyrenoidosa) cultivation was investigated. Three parameters of intermittent light, light intensity, light/dark ratio, and light/dark cycle were employed and the influence of these parameters on the productivity of Auxenochlorella pyrenoidosa was studied. The biomass yield and growth rates were mainly affected by the light fraction and cycle time. Light with 220 μE m−2 s−1 light intensity was determined as the optimal light intensity for biomass production. At the light intensity of 420 μE m−2 s−1, the results indicated that the intermittent light improved the biomass production with larger light/dark ratio compared with the continuous light. At a lower mean light intensity over time, the intermittent light should be more suitable for biomass growth and the decrease in the light/dark ratio (L/D) will lead to a higher biomass productivity. The light/dark cycle time has little influence on the biomass yield.