Decrease In Light Intensity Research Articles

Chlorella sp. Mg shows special trophic transitions and biomass production

Most microalgae have strategy to switch their growing modes depending on the availability of light and carbon sources. Unexpectedly mixotrophic Chlorella sp. Mg produced much less biomass than its heterotrophic counterpart. Investigation of the growth, photosynthetic activity, and ROS levels showed that mixotrophic Chlorella sp. Mg did not repress its photosynthesis activity upon glucose treatment, which accumulated much higher amounts of ROSs than heterotrophic one. Treatment of DCMU to the mixotrophic cells decreased photosynthetic activity and ROS levels, resulting in an increase of biomass by 62%. Decreased light intensity for the mixotrophic cells led to a similar result to that of DCMU treatment. Transcriptomic analysis showed that mixotrophic Chlorella sp. Mg did not up-regulate the hexokinase (HXK) and did not down-regulate most photosynthesis-related genes. Taken together, the algal HXK gene may not act as a glucose sensor, which could lead to unbalance of carbon metabolisms and low biomass production.

Light Intensity Modulates the Effect of Phosphate Limitation on Carbohydrates, Amino Acids, and Catechins in Tea Plants (Camellia sinensis L.).

Metabolites are major contributors to the quality of tea that are regulated by various abiotic stresses. Light intensity and phosphorus (P) supply affect the metabolism of tea plants. However, how these two factors interact and mediate the metabolite levels in tea plants are not fully understood. The present study investigated the consequences of different light intensity and P regimes on the metabolism of carbohydrates, amino acids, and flavonoids in the Fengqing tea cultivar. The leaves and young shoots were subjected to untargeted metabolomics analysis by two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC–TOF/MS), ultra-performance liquid chromatography-quadrupole-TOF/MS (UPLC–Q–TOF/MS), and targeted analysis by high-performance liquid chromatography (HPLC) along with quantification of gene expression by quantitative real time-PCR (qRT–PCR). The results from young shoots showed that amino acids, pentose phosphate, and flavonol glycosides pathways were enhanced in response to decreasing light intensities and P deficiency. The expression of the genes hexokinase 1, ribose 5-phosphate isomerase A (RPIA), glutamate synthetase 1 (GS1), prolyl 4-hydroxylase (P4H), and arginase was induced by P limitation, thereafter affecting carbohydrates and amino acids metabolism, where shading modulated the responses of transcripts and corresponding metabolites caused by P deficiency. P deprivation repressed the expression of Pi transport, stress, sensing, and signaling (SPX2) and induced bidirectional sugar transporter (SWEET3) and amino acid permeases (AAP) which ultimately caused an increase in the amino acids: glutamate (Glu), proline (Pro), and arginine (Arg) under shading but decreased catechins [epicatechingallate (ECG) and Gallic acid, GA] content in young shoots.

Elevated CO2 Enhances Dynamic Photosynthesis in Rice and Wheat.

Crops developed under elevated carbon dioxide (eCO2) exhibit enhanced leaf photosynthesis under steady states. However, little is known about the effect of eCO2 on dynamic photosynthesis and the relative contribution of the short-term (substrate) and long-term (acclimation) effects of eCO2. We grew an Oryza sativa japonica cultivar and a Triticum aestivum cultivar under 400 μmol CO2 mol−1 air (ambient, A) and 600 μmol CO2 mol−1 air (elevated, E). Regardless of growth [CO2], the photosynthetic responses to the sudden increase and decrease in light intensity were characterized under 400 (a) or 600 μmol CO2 mol−1 air (e). The Aa1, Ae2, Ea3, and Ee4 treatments were employed to quantify the acclimation effect (Ae vs. Ee and Aa vs. Ea) and substrate effect (Aa vs. Ae and Ea vs. Ee). In comparison with the Aa treatment, both the steady-state photosynthetic rate (PN) and induction state (IS) were higher under the Ae and Ee treatments but lower under the Ea treatment in both species. However, IS reached at the 60 sec after the increase in light intensity, the time required for photosynthetic induction, and induction efficiency under Ae and Ee treatment did not differ significantly from those under Aa treatment. The substrate effect increased the accumulative carbon gain (ACG) during photosynthetic induction by 45.5% in rice and by 39.3% in wheat, whereas the acclimation effect decreased the ACG by 18.3% in rice but increased it by 7.5% in wheat. Thus, eCO2, either during growth or at measurement, enhances the dynamic photosynthetic carbon gain in both crop species. This indicates that photosynthetic carbon loss due to an induction limitation may be reduced in the future, under a high-CO2 world.

Phenotyping stomatal closure by thermal imaging for GWAS and TWAS of water use efficiency-related genes.

Stomata allow CO2 uptake by leaves for photosynthetic assimilation at the cost of water vapor loss to the atmosphere. The opening and closing of stomata in response to fluctuations in light intensity regulate CO2 and water fluxes and are essential for maintaining water-use efficiency (WUE). However, a little is known about the genetic basis for natural variation in stomatal movement, especially in C4 crops. This is partly because the stomatal response to a change in light intensity is difficult to measure at the scale required for association studies. Here, we used high-throughput thermal imaging to bypass the phenotyping bottleneck and assess 10 traits describing stomatal conductance (gs) before, during and after a stepwise decrease in light intensity for a diversity panel of 659 sorghum (Sorghum bicolor) accessions. Results from thermal imaging significantly correlated with photosynthetic gas exchange measurements. gs traits varied substantially across the population and were moderately heritable (h2 up to 0.72). An integrated genome-wide and transcriptome-wide association study identified candidate genes putatively driving variation in stomatal conductance traits. Of the 239 unique candidate genes identified with the greatest confidence, 77 were putative orthologs of Arabidopsis (Arabidopsis thaliana) genes related to functions implicated in WUE, including stomatal opening/closing (24 genes), stomatal/epidermal cell development (35 genes), leaf/vasculature development (12 genes), or chlorophyll metabolism/photosynthesis (8 genes). These findings demonstrate an approach to finding genotype-to-phenotype relationships for a challenging trait as well as candidate genes for further investigation of the genetic basis of WUE in a model C4 grass for bioenergy, food, and forage production.

TrackAER: Real-Time Event-Based Particle Tracking

Event-based cameras (Lichtsteiner et al., 2008; Posch et al., 2010; Gallego et al., 2020) operate fundamentally different from frame-based cameras: Each pixel of the sensor array reacts asynchronously to relative brightness changes creating a sequential stream of events in address-event representation (AER). Each event is defined by a microsecond-accurate time stamp, the pixel position and a binary polarity indicating a relative increase or decrease of light intensity. Thus, event-based cameras only sense changes in a scenery while effectively suppressing static, redundant information. This renders the camera technology promising also for flow diagnostics. In established approaches like PIV or PTV vast amounts of data are generated, only for a large part of redundant information to be eliminated in data post-processing. In contrast, eventbased cameras effectively compress the data stream already at the source. To make full use of this potential, new data processing algorithms are needed since event-based cameras do not generate conventional framebased data. This work utilizes an event-based camera to identify and track flow tracers such as helium-filled soap bubbles (HFSBs) with real-time visual feedback in measurement volumes of the order of several cubic meters.

Application of light-emittingdiodes (LEDs) in the extensionof the cultivation period of Spirulina in Northern Vietnam

Spirulina (Arthrospira platensis) is cultured in Vietnam mainly as a functional food for humans and supplementary food for aquatic species. In the North, the most suitable time to cultivate Spirulina is from early May to late September. Other times, due to the decrease in light intensity and temperature, the growth of Spirulina significantly reduced and gave low yield, especially in the period from December to the end of February. This study investigated the influence of LEDs light on the growth of Spirulina during the periods from early March to late April (T3-T4), from early October to late November (T10-T11), and from early December to late February (T12-T2) in Hanoi. The results showed that the continuous irradiation of red LEDs increased the yield of Spirulina and pigments, phycocyanin, and chlorophyll in the two stages (T3-T4) and (T10-T11). The irradiation of both red and blue LEDs did not show a significant effect in the period T12-T2. Green LEDs did not significantly affect the growth of Spirulina. The research results provided an initial basis for the application of red LEDs to the extent of the cultivation time of Spirulina in the North of Vietnam

Enhancing Growth and Glucosinolate Accumulation in Watercress (Nasturtium officinale L.) by Regulating Light Intensity and Photoperiod in Plant Factories

Recent advancements in light-emitting diode technology provide an opportunity to evaluate the correlation between different light sources and plant growth as well as their secondary metabolites. The aim of this study was to determine the optimal light intensity and photoperiod for increasing plant growth and glucosinolate concentration and content in watercress. Two-week-old seedlings were transplanted in a semi-deep flow technique system of a plant factory for 28 days under four photoperiod–light intensity treatments (12 h—266 µmol·m−2·s−1, 16 h—200 µmol·m−2·s−1, 20 h—160 µmol·m−2·s−1, and 24 h—133 µmol·m−2·s−1) with the same daily light integral. The mean values of shoot fresh and dry weights were the highest under the 20 h—160 µmol·m−2·s−1 treatment, although there was no significant difference. Net photosynthesis and stomatal conductance gradually decreased with decreasing light intensity and increasing photoperiod. However, total glucosinolate concentration was significantly higher under 20 h—160 µmol·m−2·s−1 and 24 h—133 µmol·m−2·s−1 compared with 12 h—266 µmol·m−2·s−1 and 16 h—200 µmol·m−2·s−1. The total glucosinolate content was the greatest under 20 h—160 µmol·m−2·s−1 treatment. These data suggest that the 20 h—160 µmol·m−2·s−1 treatment promoted the maximum shoot biomass and glucosinolate content in watercress. This study supplies the optimal light strategies for the future industrial large-watercress cultivation.

The role of seasonality in reproduction of multiannual delayed gametophytes of Saccharina latissima.

Delayed gametophytes are able to grow vegetatively for prolonged periods of time. As such, they are potentially very valuable for kelp aquaculture given their great promise in opening up novel opportunities for kelp breeding and farming. However, large-scale application would require more in-depth understanding of how to control reproduction in delayed gametophytes. For newly formed gametophytes, many environmental factors for reproduction have been identified, with key drivers being light intensity, temperature, and the initial gametophyte density. However, the question of whether delayed gametophytes react similarly to these life cycle controls remains open for exploration. In this study, we performed a full factorial experiment on the influences of light intensity, temperature, and density on the reproduction of multiannual delayed gametophytes of Saccharina latissima, during which the number of sporophytes formed was counted. We demonstrate that delayed gametophytes of S.latissima can reliably reproduce sexually after more than a year of vegetative growth, depending on the effects between light intensity and temperature. Under higher light intensities (≥29µmol photons · m-2 · s-1 ), optimal reproduction was observed at lower temperatures (10.2°C), while at lower light intensities (≤15µmol photons · m-2 · s-1 ), optimal reproduction was observed at higher temperatures (≥12.6°C). Given the seasonal lag between solar radiation and sea surface temperature in natural systems, these conditions resemble those found during spring (i.e., increasing light intensity with low temperatures) and autumn (i.e., decreasing light intensity with higher temperatures). Seasonality can be used as an aquaculture tool to better control the reproduction of delayed gametophytes.

Self‐Powered Organic Electrochemical Transistors with Stable, Light‐Intensity Independent Operation Enabled by Carbon‐Based Perovskite Solar Cells

AbstractWearable sensors and electronics for health and environment monitoring are mostly powered by batteries or external power supply, which requires frequent charging or bulky connecting wires. Self‐powered wearable electronic devices realized by integrating with solar cells are becoming increasingly popular due to their ability to supply continuous and long‐term energy to power wearable devices. However, most of the solar cells are vulnerable to significant power losses with decreasing light intensity in indoor environment, leading to an errant device operation. Therefore, stable autonomous energy in a reliable and repeatable way without affecting their operation regime is critical to attaining accurate detection behaviours of electronic devices. Herein, we demonstrate, for the first time, a self‐powered ion‐sensing organic electrochemical transistor (OECT) using carbon electrode‐based perovskite solar cells (CPSCs), which exhibits highly stable device operation and independent of the incident light intensity. The organic electrochemical transistors (OECTs) powered by CPSCs maintained a constant transconductance (gm) of ≈60.50 ± 1.44 µS at light intensities ranging from 100 to 0.13 mW cm−2. Moreover, this self‐powered integrated system showed good sodium ion sensitivity of −69.77 mV decade−1, thereby highlighting its potential for use in portable, wearable, and self‐powered sensing devices.

Lux study: Contribution of a three-dimensional, high dynamic range, ultra-high-definition heads-up visualization system to a significant delivered light intensity decrease during different types of ocular surgeries

To explore the hypothesis that using a large, three-dimensional (3D), ultra-high-definition (4K), heads-up display (HUD) system in a real-life setting may be associated with a significant reduction in light intensity (LI) delivered during various types of eye surgery. Single center, post-learning curve observational study of 142 independent consecutive cases: 73 cataracts and 69 vitrectomies (VR). For each group, the only variable setting was the LI. The LI delivered by each source was calibrated in lumens (lm). In the VR group, the delivered LI dramatically decreased from the 80% reference to 27.8%±13.2% (P<0.0001) (4.3 to 1.5lm). Among these surgeries, 91.3% needed 40% or less LI (2.3lm). The corneal transparency and quality of pupil dilation showed some correlation with the results. In the cataract group, the difference was even more spectacular, from 80% to 15%±11.3% (P<0.0001) (2.5 to 0.3lm). Among these surgeries, 80.8% required less than 20% LI (0.5lm). The surgical time, LI variations and type of cataract seemed to influence the results, down to 9.6%±5.4% (P<0.0001) (0.22lm) for nuclear cataracts, which represented 63% of the cataract sample. The digital signal amplification with this HUD system allows comfortable posterior as well as anterior segment surgery despite the decrease in incident light, suggesting an unprecedented reduction in the risk of phototoxicity compared to conventional systems as well as a likely improvement in patient comfort.

In the shade – Screening of medicinal and aromatic plants for temperate zone agroforestry cultivation

Agroforestry is one of the best land use management systems that regenerate degraded agroecosystems while maintaining high productivity. However, current knowledge about how shade from trees affects the cultivation of medicinal and aromatic plants in temperate zones is lacking. Therefore, the authors explored the effects of shade on the most important cultivation parameters of medicinal and aromatic plants. A three-year-long open field study was conducted with a control (C) and two artificial shade treatments (30 % - T1 and 50 % - T2 light intensity decrease). Shade effects on seven different species were evaluated for plant height and width, fresh yield, drug mass, essential oil content, and content of other biologically active compounds. Our first hypothesis was confirmed, because we observed pronounced species-specific shade tolerance. Secondly, it was proven that there are species of medicinal and aromatic plants — grown in temperate climates — for which it is possible to produce the quality of drug specified in the professional standards. They provide adequate yields even under mild (30 %) shade conditions. Consequently Calendula officinalis L., Dracocephalum moldavica L., Melissa officinalis L. and Satureja hortensis L. are highly recommended for further agroforestry experiments in large-scale and authentic agroforestry conditions. Mild shade (30 %) had favourable effects on several species in our experiments; however, 50 % shade produced no favourable effect on any examined species. Therefore, we suggest temperate zone medicinal agroforestry systems be designed such that the shadow should not exceed 30 %.

Correlation Among Phenotypic Parameters Related to the Growth and Photosynthesis of Strawberry (Fragaria × ananassa Duch.) Grown Under Various Light Intensity Conditions.

The objective of this study was to investigate characteristics of phenotypic parameters such as physiology, yield, and fruit quality responses of strawberry (Fragaria × ananassa Duch.) to various light intensity conditions (VLICs), and to determine the correlations among these phenotypic parameters. Strawberry plants were cultivated in a smart greenhouse separated into four areas, three of which were completely shaded by curtains from 20:00 until 10:00 (3 hS), 12:00 (5 hS), and 14:00 (7 hS), respectively. The fourth area was a non-shaded control treatment (0 hS). The ambient light intensities during the experimental period for the 0, 3, 5, and 7 hS treatments were 1,285, 1,139, 770, and 364 mol⋅m–2, respectively. Strawberry plants grown under low light intensity conditions experienced decreases in photosynthetic rate, stomatal conductance, and sugar accumulation compared to the 0 hS. Petiole generation and fruit yield were also sharply decreased in proportion to the degree of decrease in light intensity. In contrast, photosynthetic pigment content was shown to increase under low light conditions. Organic acid contents (excluding acetic acid) and leaflet size did not change significantly under low light conditions compared to the 0 hS. Changes to light intensity are considered to induce changes to the phenotypic characteristics of strawberry plants to favor growth using the energy and carbon skeletons obtained through respiration and photosynthesis. In the 7 hS treatment, where light intensity was drastically reduced, NPQ, qP, and RFd values as chlorophyll a fluorescence parameters were significantly lowered, which could indicate their measurement as an important technique to check the stress response of plants grown in low light conditions.

Implications of Wound Healing on Subcutaneous Photovoltaic Energy Harvesting.

Cardiac pacemakers must be regularly replaced due to depleted batteries. A possible alternative is proposed by subcutaneous photovoltaic energy harvesting. The body's reaction to an implant can cause device encapsulation. Potential changes in spectral light transmission of skin can influence the performance of subcutaneous photovoltaic cells and has not yet been studied in large animal studies. Subcutaneous implants measuring changes in the light reaching the implant were developed. Three pigs received those implants and were analyzed for seven weeks. Spectral measurements with known irradiation were performed to identify possible changes in the transparency of the tissues above the implant during the wound healing process. A histological analysis at the end of the trial investigated the skin tissue above the subcutaneous photovoltaic implants. The implants measured decreasing light intensity and shifts in the light's spectrum during the initial wound healing phase. In a later stage of tissue recovery, the implants measured a generally reduced light intensity compared to the healthy tissue after implantation. The spectral distribution of the measured light at the end of the trial was similar to the first measurements. The histological analysis showed subcutaneous granulation tissue formation for all devices. The varying reduction of light intensity reaching the implants means that safety margins must be sufficiently high to ensure the power. At the end of the wound healing process, the spectral distribution of the light reaching the implant is similar to healthy tissue. Optimizations of spectral sensitivity of photovoltaic cells are possible.

Enhanced Photoresponse of Single GaN Microwire Ultraviolet Photodetectors by Heteroepitaxial AlN Coating Layer

AbstractCore–shell heterojunction structure is a feasible approach to optimize the optoelectronic performance of devices by combining the advantages of different materials. In this work, GaN/AlN core–shell heterojunction microwire‐based photodetector (PD) has been fabricated, and appropriate epitaxy growth of AlN can improve the performances of PDs. Compared with pure GaN microwire device, the enhanced responsivity, sensitivity, detectivity, and external quantum efficiency value of 4160 A W−1, 1.88 × 107%, 3.93 × 1012 Jones, and 4.07 × 106% are obtained with 5 nm thick AlN. Meanwhile, a rise/decay time of 25/16 ms is possessed. In addition, the responsivity and detectivity are increased with an acceptable decrease in sensitivity when the exciting light intensity decreases. The effective advances of PDs are benefited from the increased Schottky barrier height, the built‐in electric field that promotes the separation of photogenerated electron‐hole pairs, and direct heteroepitaxial growth high crystal quality GaN/AlN core/shell structure, which will effectively passivate the surface of GaN microwire by covering AlN. This study sheds some light on fabricating high‐performance microwire‐based PDs.

Omnivorous Carp (Carassius gibelio) Increase Eutrophication in Part by Preventing Development of Large-Bodied Zooplankton and Submerged Macrophytes

Fish, being an important consumer in aquatic ecosystems, plays a significant role by affecting the key processes of aquatic ecosystems. Omnivorous fish consume a variety of food both from pelagic and benthic habitats and may directly or indirectly affect the plankton community as well as the lake trophic state. We conducted a 72-day outdoor experiment in mesocosms with and without Prussian carp (Carassius auratus) to evaluate the effect of this often-stocked omnivorous fish on the plankton community and water quality. We found that the presence of fish increased the biomass of planktonic algae, total and inorganic suspended solids, leading to decreased light intensity in the water and a lower biomass of benthic algae. Fish also prevented development of submerged macrophytes and the establishment of large-bodied zooplankton. However, the fish did not increase nitrogen concentrations and even was lowered total phosphorus levels, in part due to nutrient storage in the fish. We conclude that stocking of Prussian carp should be avoided, or removed where stocked and abundant, to obtain good ecological quality of shallow lakes, characterized by clear water and high abundance of macrophytes.

Evaluation of Air Temperature, Photoperiod and Light Intensity Conditions to Produce Cucumber Scions and Rootstocks in a Plant Factory with Artificial Lighting

Air temperature and light conditions are important factors not only to produce high-quality seedlings but also to promote energy efficiency in a plant factory with artificial lighting. In this study, we conducted two experiments in order to investigate the favorable conditions of air temperature, light intensity and photoperiod for the production of cucumber scions and rootstocks in a plant factory with artificial lighting. Cucumber scions and rootstocks were cultivated in two combined treatments: the combination of three different levels of difference between the day and night temperature (DIF), 25/20, 26/18 and 27/16 °C and five different light intensity conditions of photosynthetic photon flux, 50, 100, 150, 200 and 250 μmol·m−2·s−1 was set for the first experiment, and the combination of three different photoperiod conditions, 12, 16 and 20 h·d−1 and five different light intensity conditions, 50, 100, 150, 200 and 250 μmol·m−2·s−1 was set for the second experiment. In the air temperature and light intensity treatments, the hypocotyl elongation of cucumber scions and rootstocks was affected more largely by light intensity than DIF. The highest DIF treatment (27/16 °C) affected negatively on the accumulation of dry mass. On the contrary, the smallest DIF treatment (25/20 °C) was favorable for seedling growth due to lesser stress by rapid change of air temperature between photo- and dark-period. In the photoperiod and light intensity treatments, an increased DLI (daily light integral) promoted the growth of scions and rootstocks. Under the same DLI condition, the growth of scions and rootstocks increased with increasing photoperiod and decreasing light intensity. In both of experiments, while the dry weight increased with increasing the light intensity, the light use efficiencies were reduced by increasing the light intensity. Considering the growth and quality of seedlings and energy efficiency, the optimal environment conditions were represented by 25/20 °C of air temperature, 150 μmol·m−2·s−1 of light intensity and 16 h·d−1 of photoperiod.

The effect of plastic debris attachment to the health of branching corals in Kelapa Dua Island, Thousand Islands

Plastic marine debris are a potential threat to the life of marine organisms such as corals. This study aimed to analyze the effect of different plastic waste attachments on the bleaching rate and the health of branching corals at Kelapa Dua Island. Branching coral colonies consisted of 15 fragments of Porites cylidrica at the water depth of 80-90 cm, then treated with plastic waste (control, clear plastic, sack plastic, packaging plastic, and black plastic) for four days. Determination of color changes in corals was determined using Adobe Photoshop CC 2019 and Image j software to obtain the area of the discoloration. The treatment with black plastic became most impactful, with a discoloration area of 5.33 ± 0.48 cm2 and a healthy percentage of 73.62 ± 2.00%. Results of the linear regression between coral discoloration rate and light intensity showed a negative correlation, with r = -0.77 and R2 = 0.59, then between the percentage of coral health and light intensity showed a positive correlation, with r = 0.83 and R2 = 0.69. These results indicated that the decrease in light intensity due to the covered plastic debris affected the discoloration rate and the health percentage of branching coral.

Morphological and Physiological Responses of Pinus massoniana Seedlings to Different Light Gradients

Light intensity is a critical factor regulating photosynthetic capacity in plants. However, the effects of varying light intensity on morphological and photoprotective mechanisms in Pinus massoniana seedlings have not been explored in depth, especially those in the first seedling growing season. We measured the growth, photosynthetic physiology, biochemistry, and chlorophyll fluorescence of P. massoniana seedlings at four light gradients: 100% relative irradiance (RI, full sunlight), 70% RI, 50% RI, and 20% RI. The seedling height at 70% RI was 9.27% higher than that at 100% RI. However, seedling height was inhibited under low light intensity; at 20% RI, all seedlings died. The decreasing light intensity inhibited ground diameter growth but increased the height-diameter ratio. The secondary needle emergence rate was 53.4% higher at 70% RI than at 100% RI but was only 2% at 50% RI. The chlorophyll and carotenoid contents increased significantly with decreasing light intensity. The increased Chl b and Car contents promoted the photoreceptor potential of the violet (400~420 nm), blue (440~480 nm), and yellow-orange (597~655 nm) regions in leaves. Among the chlorophyll fluorescence parameters, Fv/Fm, Fv′/Fm′, Y(II), qp, and ETR all reached maximum values at 70% RI but were significantly lower at 50% RI than at 100% RI. However, decreasing the light intensity caused a reduction in NPQ. The 70% RI level increased POD and SOD activity and the contents of osmotic regulation substances and slowed MDA accumulation. Seedlings at 70% RI had a higher growth rate, higher photosynthetic activity and potential, and significantly greater stress resistance than the other seedlings. Therefore, appropriate shading measures were beneficial to the cultivation of vigorous seedlings. Furthermore, spectral reflectance indexes were found to be a suitable tool for monitoring the photosynthetic physiological characteristics, stress resistance characteristics, and growth status of P. massoniana seedlings in real time.

Research on the Coordinated Control of Photovoltaic Microgrid Based on Micro Gas Turbine

The hybrid microgrid can make full use of&nbsp;the&nbsp;distributed generation to supplement the large power grid, but different power sources need to be coordinated before&nbsp;supplying&nbsp;more stable power.&nbsp;This study&nbsp;proposed&nbsp;an improved coordinated control strategy for the heterogeneous power in the hybrid microgrid. In this strategy, the reference power of&nbsp;the&nbsp;gas turbine&nbsp;was calculated by the predictive algorithm instead of the traditional reference power calculation method. Then, the simulation experiment was&nbsp;carried out. The results show that&nbsp;the micro gas turbine would&nbsp;provide the power when the photovoltaic output power was insufficient to bear the local load due to the decrease of light intensity, and&nbsp;the gas turbine under the improved control strategy&nbsp;was faster; the distribution network bus caused by the sudden change of illumination had&nbsp;smaller&nbsp;voltage fluctuation&nbsp;and shorter duration&nbsp;under the improved coordinated control strategy; the fifth&nbsp;and seventh harmonics generated by the voltage fluctuation were&nbsp;smaller&nbsp;under the improved strategy.

Study on preparation of graphene oxide thin film layers: the electrical and dielectric characteristics of Au/GO/n-type Si junction structures

We investigated results of light intensity on electrical characteristics of Au/Graphene Oxide (GO)/n–Si junction structures in dark and under different light intensities at 300 K (absolute temperature). Different electric and dielectric parameters of the prepared Au/GO/n–Si junction structure were analyzed from the current–voltage (I–V), capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements. The main electrical properties such as ideality factors n, zero-bias barrier heights Φb and series resistances RS of Au/GO/n–Si junction structures obtained from different techniques in under dark and light intensities at 300 K using forward I–V measurements. The Au/GO/n–Si junction structure shows a not ideal behavior because of the interfacial layer, the interface states or the series resistance. The barrier height is decreased, while the ideality factor is increased with decreasing light intensities. Furthermore, the dielectric properties of Au/GO/n-type Si junction structures were obtained using C–V and G/ω–V characteristics in the frequency ranges 10–1000 kHz at 300 K. It is seen that the values of dielectric constant (e′), dielectric loss (e″), and loss tangent (tanδ) decreases with increasing frequency while ac the electrical conductivity (σac) increases with increasing frequencies.