Light Intensity Conditions Research Articles

The Response of Extracellular Polymeric Substances Production by Phototrophic Biofilms to a Sequential Disturbance Strongly Depends on Environmental Conditions.

Phototrophic biofilms are exposed to multiple stressors that can affect them both directly and indirectly. By modifying either the composition of the community or the physiology of the microorganisms, press stressors may indirectly impact the ability of the biofilms to cope with disturbances. Extracellular polymeric substances (EPS) produced by the biofilm are known to play an important role in its resilience to various stresses. The aim of this study was to decipher to what extent slight modifications of environmental conditions could alter the resilience of phototrophic biofilm EPS to a realistic sequential disturbance (4-day copper exposure followed by a 14-day dry period). By using very simplified biofilms with a single algal strain, we focused solely on physiological effects. The biofilms, composed by the non-axenic strains of a green alga (Uronema confervicolum) or a diatom (Nitzschia palea) were grown in artificial channels in six different conditions of light intensity, temperature and phosphorous concentration. EPS quantity (total organic carbon) and quality (ratio protein/polysaccharide, PN/PS) were measured before and at the end of the disturbance, and after a 14-day rewetting period. The diatom biofilm accumulated more biomass at the highest temperature, with lower EPS content and lower PN/PS ratio while green alga biofilm accumulated more biomass at the highest light condition with lower EPS content and lower PN/PS ratio. Temperature, light intensity, and P concentration significantly modified the resistance and/or recovery of EPS quality and quantity, differently for the two biofilms. An increase in light intensity, which had effect neither on the diatom biofilm growth nor on EPS production before disturbance, increased the resistance of EPS quantity and the resilience of EPS quality. These results emphasize the importance of considering the modulation of community resilience ability by environmental conditions, which remains scarce in the literature.

Biochemical Basis for the Time-of-Day Effect on Glufosinate Efficacy against Amaranthus palmeri

Glufosinate, a glutamine synthetase (GS) inhibitor, often provides variable weed control depending on environmental conditions such as light, temperature and humidity at the time of application. Midday applications normally provide improved efficacy compared to applications at dawn or dusk. We investigated the biochemical basis for the time-of-day effect on glufosinate efficacy in Amaranthus palmeri. GS1/GS2 gene expression and GS1/GS2 protein abundance were assessed in different parts (young leaves, old leaves, and roots) of plants incubated in the dark compared to those in the light. The turnover of GS total activity was also evaluated overtime following glufosinate treatment at midday compared to dusk application. The results suggest that GS in A. palmeri is less expressed and less abundant in the dark compared to in the light. Midday application of glufosinate under intense light conditions following application provide full control of A. palmeri plants. Consequently, these plants are unable to recover GS activity by de novo protein synthesis. Full activity of GS is required for complete inhibition by the irreversible inhibitor glufosinate. Therefore, glufosinate applications should always be performed in the middle of the day when sunlight is intense, to prevent weed escapes from the herbicide treatment.

The Artificial Lighting Analysis of Study Rooms in Dormitories and Classrooms Islamic Boarding School Of Lil Banat Parepare

This study aims to find out the intensity of light in the study room of Islamic boarding school of DDI Lil Banat Parepare. Measurements are taken in rooms that are often used by students to learn, namely classes and dormitories. The type of research used is quantitative by simulation method. Variables are tied to exposure measurement i.e. light intensity. While the variables are free, namely the arrangement of light points and the layout of the study room. Measurements were carried out over three days using a digital lux meter tool. The measurement results showed that the intensity of light in the dormitory did not meet the Indonesian National Standard for study space both night and day. During the day classrooms meet Indonesian National Standards but not at night. Although students as a space user is comfortable with the condition of light intensity in the study room and can learn according to these conditions, students still feel some complaints in the form of sore eyes, tense eyes and difficulty focusing. Thus, researchers made recommendations on the design of study rooms that can make students more comfortable learning in dormitories and classrooms so as to reduce complaints while studying. Lighting design recommendations are made in several alternatives by adding the number of lamps and changing the type of lamp using Dialux simulation. The simulation results of the study room lighting design recommendations have met the standards for use so that it can be applied to dormitories and classes at the Islamic boarding school of DDI Lil Banat Parepare.
 
 Keywords: Artificial lighting design; study room; light intensity

Алелопатичний вплив мікроводоростей на пшеницю озиму

The results of the study of the allelopathic activity of the culture medium of two species of green and charophyte microalgae (Chlorella vulgaris Beijer. and Interfillum terricola (J.B.Petersen) Mikhailyuk et al.) to winter wheat (Triticum aestivum L.) in model pot experiments with the aim to discover of physiological mechanisms of allelopathy and finding effective and safe compounds with growth-promoting effects. The microalgae culture medium was applied in a rate of 1; 3 and 10 mL per a pot (250 mL) filled with sifted and sterilized gray podzolic soil, before sowing wheat seeds. Test plants were grown in a phytochamber under controlled conditions of light intensity, temperature and soil moisture. The number of germinated seeds was recorded from the 2nd to the 8th day after sowing. The vitality of winter wheat was evaluated at the end of the experiments using morphometric characteristics of growth (height of aboveground parts, leaf surface area, length of root system, number of lateral roots; dry matter mass of aboveground parts and roots) and content of photosynthetic pigments in leaves. At the end of the experiment, the indicators of electrical conductivity, redox potential, pH and content of nutrients in the soil were determined. The positive effect of microalgae on seed germination, growth and photosynthetic apparatus of T. aestivum plants was established. Culture medium of C. vulgaris showed a higher stimulating effect on seed germination and growth of wheat seedlings than I. terricola. The positive effect of microalgae on the photosynthetic activity of wheat and the content of organic carbon in the soil indicates the possibility of developing of biofertilizers based on them in order to improve the structural and functional organization of agroecosystems. The obtained results confirmed the prospects of C. vulgaris as a biofertilizer in crops. The allelopathic effect of I. terricola on vascular plants has been studied for the first time. The important role of indirect allelopathic mechanisms in the interactions between the studied species of microalgae and vascular plants has been established.

Regeneration Dynamics on Treefall Mounds and Pits for 10 Years after a Windfall in a Natural Mixed Forest

The treefall mounds and pits resulting from uprooting caused by strong winds is an indispensable microtopography for the regeneration of many tree species through improved light conditions and mineral soil exposure. These microtopographies are expected to become more important because global warming is predicted to increase windstorm frequency. This study aimed to clarify the characteristics of mounds and pits that contribute to the early establishment of major tree species in a natural mixed forest of northern Japan. The 39 tip-up mounds caused simultaneously by a strong typhoon in September 2004 were selected. In 2006, light intensity and soil moisture contents were measured in each mound and pit. Seedlings of all tree species were counted, and in 2014, the height of saplings was measured. The initial seedling density, regardless of tree species, was significantly higher in the pits than on the mound, but the density at the 10-th growing season decreased significantly in the pits and was comparable between the two locations. Intense light conditions favor regeneration of Betula sp. (Betula platyphylla and B. ermanii). In contrast, for Abies sachalinensis and Picea glehnii, the light intensity had a negative effect, so it was concluded that regeneration of conifers would be limited under the condition where strong winds form large gaps.

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.

Response of Red Maple (Acer rubrum L.) Micropropagation to Different In Vitro Conditions

A reliable micropropagation protocol was developed for Red Maple tree for the first time in Iraqi Kurdistan Region to introduce this newly entered species to the local community. At initiation stage, healthy and vigorous cultures were established following a critical disinfestation protocol by bleach (Sodium hypochlorite) at 2.5 % for 20 minutes. The obtained results show that shoots multiplication was successfully enhanced by recording the highest number of shoots and leaves per explant when 0.5 mg.L-l BA was added to WPM by recording 2.08 shoots/ explant and 13.7 leaves/ explant, respectively. Whereas, the longest shoots were obtained when 1.5 mg.L-l BA was added by reaching 1.86 cm. For root formation, IBA was more effective than NAA by giving the best rooting parameters. The highest number of roots per explant (3.00 roots/ explant), the longest roots (5.87 cm) and the highest rooting percentage (100%) were obtained when 0.1 mg.L-l IBA was added to WPM. The half-light intensity (50 feet/ candle) showed better rooting abilities of microshoots than full light intensity conditions (100 feet/ candle) by raising the number of roots from 3.00 to 4.00 roots/ explants, increasing the mean length of roots from 5.87 cm to 6.37 cm when the comparing between the highest rooting parameters at full light illumination. A 100% survival rate was achieved from the acclimatized plantlets in the greenhouse conditions without any abnormal morphological characteristics. It can be recommended that this important plant can be propagated by tissue culture technique toward mass production in the local area.

Efficacy of ethyl ascorbyl ether-containing cosmetic cream on blue light-induced skin changes.

Office workers are consistently exposed to blue light, mainly from sunlight and digital device. Recent studies report that blue light has various harmful effects, including cellular changes via reactive oxygen species. Studies on blue light-induced skin changes have only been conducted in vitro and have not been clinically confirmed. We provide novel methods to evaluate the effect of the product on the recovery of skin changed by blue light. Internet surveys were conducted for workers in their 20s and 40s regarding exposure time to blue light in various environments. To study the effects of long-term exposure to blue light (456nm) on the skin, we designed three light intensity conditions, and various skin characteristics were observed. After blue light irradiation, various skin characteristics were analyzed before and after applying ethyl ascorbyl ether (EAE)-containing cosmetic cream for 2weeks. When exposed to strong blue light for approximately 16days, the L* value, skin hydration, transparency, and elasticity decreased, and the melanin index, erythema index, a* value, and b* value increased. Furthermore, after short-term blue light irradiation (dose, 269J/cm2 , the equivalent of blue light exposure for approximately 38days in daily life), the L* value and elasticity decreased, and the melanin index and erythema index increased. However, when EAE cream was applied on skin for 1-2weeks, the skin recovered. This study clinically confirms the skin changes caused by blue light and the effect of EAE in relieving such changes.

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 Role of Membranes and Lipid-Protein Interactions in the Mg-Branch of Tetrapyrrole Biosynthesis.

Chlorophyll (Chl) is essential for photosynthesis and needs to be produced throughout the whole plant life, especially under changing light intensity and stress conditions which may result in the destruction and elimination of these pigments. All steps of the Mg-branch of tetrapyrrole biosynthesis leading to Chl formation are carried out by enzymes associated with plastid membranes. Still the significance of these protein-membrane and protein-lipid interactions in Chl synthesis and chloroplast differentiation are not very well-understood. In this review, we provide an overview on Chl biosynthesis in angiosperms with emphasis on its association with membranes and lipids. Moreover, the last steps of the pathway including the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), the biosynthesis of the isoprenoid phytyl moiety and the esterification of Chlide are also summarized. The unique biochemical and photophysical properties of the light-dependent NADPH:protochlorophyllide oxidoreductase (LPOR) enzyme catalyzing Pchlide photoreduction and located to peculiar tubuloreticular prolamellar body (PLB) membranes of light-deprived tissues of angiosperms and to envelope membranes, as well as to thylakoids (especially grana margins) are also reviewed. Data about the factors influencing tubuloreticular membrane formation within cells, the spectroscopic properties and the in vitro reconstitution of the native LPOR enzyme complexes are also critically discussed.

Multi-fold enhancement in vitamin E (alpha-tocopherol) production via integration of bioprocess optimisation and metabolic engineering in cell suspension of sunflower

Alpha-tocopherol, a highly active form of the antioxidant vitamin E in humans, effectively scavenges free radicals and protects the cell membranes. The aim of our study was to enhance alpha-tocopherol production in sunflower cell suspension using elicitation, precursor addition and culture condition optimization. Among various elicitors and precursors studied, sodium chloride (50 mg/L) added as elicitor and phytol (50 mg/L) added as the precursor to an untransformed sunflower cell suspension, resulted in maximum productivity enhancement of alpha-tocopherol up to 2.3- and 1.9-fold, respectively compared to a control untransformed sunflower cell suspension (0.02 mg/L/d). In separate experiments, the volumetric productivity of alpha-tocopherol in the untransformed suspension was enhanced up to 2.1- fold (0.09 mg/L/d) under optimized conditions of light intensity (3500 lx), temperature (30 °C), initial pH (6.5) and inoculum size (6 g/L). We then extrapolated these strategies (elicitor and precursor addition, culture condition optimization) for implementation on a high alpha-tocopherol yielding metabolically engineered cell suspension overexpressing 4-hydroxyphenylpyruvate dioxygenase (TS4), which resulted in enhancement (1.9-, 1.45- and 2.72-fold respectively) in the volumetric productivity of alpha-tocopherol compared to the transformed cell suspension grown under control conditions (0.18 mg/L/d). Thus, integration of bioprocess optimization and metabolic engineering resulted in a multi-fold (up to 12-fold) enhancement in alpha-tocopherol productivity in comparison to the untransformed cells. Therefore, our study demonstrates that productivity enhancement strategies like bioprocess optimisation and metabolic engineering (developed separately in parallel) for a given system can be combined to achieve maximum productivity in lesser time and cost than a relay system of optimization in long-duration plant cell cultivations.

Changes in Growth of Watermelon Scions and Rootstocks Grown under Different Air Temperature and Light Intensity Conditions in a Plant Factory with Artificial Lighting

Changes in Growth of Watermelon Scions and Rootstocks Grown under Different Air Temperature and Light Intensity Conditions in a Plant Factory with Artificial Lighting

Identification of butt welded joint penetration based on infrared thermal imaging

In the gas metal arc welding (GMAW) process, the intense arc light and high temperature conditions bring great difficulties to the online identification of welded joint penetration. At present, visual sensing method and arc sound detection method are mainly used to identify the welded joint penetration, there are few reports about using welding temperature field to identify welded joint penetration. In this paper, a method of using infrared thermal imaging to identify the welded joint penetration was proposed, a single infrared thermal imager was used to monitor the welding temperature field in real time, the solidified weld area outside the weld pool area was selected as the region of interest (ROI) for real-time temperature measurement. The temperature field distribution features of ROI were extracted, taking these features as input and welded joint penetration as output, the identification model for welded joint penetration was established based on artificial neural network (ANN). The identification accuracy and generalization ability of the identification model were verified by a variety of butt welding experiments, the experimental results show that the identification accuracy of the established model for three penetration states of welded joint is higher than 96%, which can be applied in the online identification of welded joint penetration.

Recycling of shrub landscaping waste: Exploration of bio-hydrogen production potential and optimization of photo-fermentation bio-hydrogen production process

Shrub landscaping waste, derived from afforestation of city, has increased annually, making it a promising feedstock for energy production. In this work, the photo-fermentation bio-hydrogen production potential from shrub landscaping waste was evaluated. Eight kinds of shrub landscaping wastes (Photinia fraseri, Buxus megistophylla, Buxus sinica, Pittosporum tobira, Sabina Chinensis, Berberis thunbergii, Ligustrum vicaryi and Ligustrum quihoui) were selected as substrate and the photo-fermentation bio-hydrogen production process of which was optimized. Buxus megistophylla was found to be the most suitable substrate for photo-fermentation bio-hydrogen production. Moreover, the initial pH value, temperature and substrate concentration had significant influence on photo-fermentation bio-hydrogen production. The maximum cumulated hydrogen yield of Buxus megistophylla was 73.82 ± 0.06 mL/g TS under the optimal conditions of light intensity of 3000 Lux, substrate mass concentration of 21.49 g/L, temperature of 29.78 °C, inoculant amount of 25% and initial pH value of 6.78.

Effects of two water regimes on morphological traits, nutritive value and physiology of three Bituminaria bituminosa varieties from the Canary Islands

AbstractMorphological traits, nutritive values and physiological responses to two different water regimes of three Bituminaria bituminosa varieties: var. albomarginata, var. crassiuscula and var. bituminosa were evaluated in a greenhouse experiment. Two water regimes were imposed for 63 days; well‐watered (WW) plants and deficit‐watered (DW) plants, both starting from a high soil water content (dripping point). The three varieties showed similar aerial biomass reduction under reduced watering, 50% for var. albomarginata, 51% for var. bituminosa and 43% for var. crassiuscula. Var. Albomarginata showed lower shoot biomass under both water regimes than var. bituminosa (56.2% in WW plants and 55.2% in DW plants) and var. crassiuscula (52% in WW plants and 57.8% in DW plants). This lower shoot biomass could be attributed to the high initial soil water content imposed in this experiment, affecting early development. This hypothesis is supported by the lower root biomass production of var. albomarginata and its distribution. The DW treatment of this experiment was not sufficiently restrictive to cause morphological modifications, whilst of the forage quality variables analysed, only ash was affected. Var. crassiuscula and var. albomarginata had a lower specific leaf area (239 cm2 g‐1 and 235 cm2 g‐1, respectively) than var. bituminosa (352 cm2 g‐1), which might represent an important adaptation to high light intensity and temperature conditions. The values of stem mass fraction (SMF) and leaf mass fraction (LMF) for var. crassiuscula (SMF = 0.36 and LMF = 0.28) and var. albomarginata (SMF = 0.35 and LMF = 0.36) indicated better forage aptitude of these varieties than var. bituminosa (SMF = 0.50 and LMF = 0.19). All varieties showed good values of crude protein and digestibility, although important differences were found between leaf and stem. According to the studied morphological, nutritional and physiological traits, var. albomarginata showed the best aptitude for being introduced as permanent grasslands in some Mediterranean farming systems. However, the possible susceptibility of var. albomarginata to high water content in the soil could limit its introduction. These results help to inform the potential use of these three Canarian B. bituminosa varieties to improve Mediterranean rainfed grasslands of extensive farming systems.

The photo response properties of shape memory alloy thin film based photodiode

In this work, the CuAlMn shape memory alloy (SMA) composed as Cu-12.28Al-2.84Mn in wt.% (=72.49Cu-24.70Al-2.81Mn in at.%) was used as a thin Schottky contact layer on an n-Si wafer to produce a Schottky type Al/CuAlMn/n-Si/Al photodiode. To do this, in the first stage of the experimental route, the CuAlMn alloy was prepared in succession by casting in arc melter, homogenizing in β-phase region and lastly by quenching in iced-brine water. Then, the shape memory effect characteristics were revealed by the widely-used thermal (DSC and DTA) and structural (EDS and XRD) characterization tests that been carried out on the alloy. Then, the alloy was thermally evaporated and deposited on the n-Si wafer as a thin film nano layer to make the Al/CuAlMn/n-Si/Al photodiode. The current-voltage (I-V) analysis of the diode taken under dark and different light intensities revealed the rectifying behavior of the diode. The work function value of CuAlMn alloy film was determined as 4.747±0.17 eV. The reverse bias current values of the diode under light were found to be greater than the value observed under dark. The results showed that the diode has a considerable photoconducting feature. The characteristic electrical diode parameters of the junction were computed by using the traditional I-V method. By taking into consideration the literature works related to SMA layered photodiodes, some of the photodiode parameters such as responsivity, photosensitivity, and detectivity, not been reported so far, were determined for the first time. The SMA/n-Si device showed an excellent photosensitivity (~105) performance, and also good merits of responsivity, and detectivity. Which implied that the produced device can be used in various optoelectronic applications. The transient photocurrent (TPC) measurement was performed under the various light intensity conditions and the related characteristic photodiode parameters were determined. Additionally, the capacitance-voltage (C-V) measurement of the SMA-layered photodiode was also carried out at room temperature and different frequencies. The capacitance of the device was observed to be quite sensitive to frequency. Furthermore, a solution suggestion for SMA film cracks and related fractures was also discussed.

The role of salt stress on laboratory cultivation of green macroalga Enteromorpha compressa and its antioxidant activity

Cultivation of the green seaweed Enteromorpha compressa was performed under natural laboratory spring environmental conditions of temperature, light intensity and photoperiod to study the salinity tolerance of this intertidal green macroalga. Cultivation was carried out under artificial seawater (ASW) of different concentrations (18, 35, 53 and 106 g/l sea salt) compared to the control using natural seawater (NSW). Growth rate and pigment content of the cultivated alga were recorded at regular intervals during the experimental duration. Antioxidant activity of the crude ethanolic extract and its fractions (petroleum ether, chloroform, ethyl acetate and acetone) was performed against DPPH radical scavenging assay and compared to the standard synthetic antioxidant butylated hydroxy-toluene (BHT). The finding showed that enhancement of algal growth rate under ASW concentrations of 35, 53 and to a lesser extent at 106 g/L during the first 15 days of cultivation were due to the increased pigment biosynthesis, photosynthetic and metabolic activities and followed by gradual retardation due to the impact of prolonged salt stress. Antioxidant activity of alga was found to be concentration, type of extract and incubation time dependent. Acetone fraction of all salt concentrations showed higher antioxidant activity compared to other fractions. Pronounced activity was recorded at higher seawater conc. (106g/l).

Suppression of Defects Through Cation Substitution: A Strategic Approach to Improve the Performance of Kesterite Cu2ZnSn(S,Se)4 Solar Cells Under Indoor Light Conditions

Recent efficiency advancements in kesterites have reinforced the use of Cu2ZnSn(S,Se)4 (CZTSSe) in indoor photovoltaic applications. However, the performance of kesterites under low light intensity conditions is mainly hindered by deep‐level defects. In this study, a strategic approach of silver (Ag) and germanium (Ge) cation substitution to cure these defects are employed. The Ag‐doped CZTSSe (CZTSSe:Ag) and Ge‐doped (CZTSSe:Ge) samples experimentally demonstrated a significant improvement in kesterite device performance under all intensities of LED and white fluorescent lamp conditions are prepared. Interestingly, the CZTSSe:Ag device exhibited the highest performance levels, i.e., 1.2–1.5 and 2.5–3 times better than those of Ge‐doped CZTSSe:Ge and undoped CZTSSe, respectively. This improved device performance is mainly attributed to the reduced energy level of deep‐level defects in CZTSSe:Ag. Moreover, these defects assisted in the generation of a larger potential difference between the grain boundary and grain interior in the CZTSSe:Ag sample, attracting minority carriers near the grain boundary. Consequently, the improved carrier separation process reduced the carrier recombination losses and enhanced the power output under low light intensity conditions. This Ag and Ge cation substitution in kesterite is found to be an effective approach to improve the device performance under low light intensity conditions.

IAA3-mediated repression of PIF proteins coordinates light and auxin signaling in Arabidopsis.

The exogenous light signal and endogenous auxin are two critical factors that antagonistically regulate hypocotyl growth. However, the regulatory mechanisms integrating light and auxin signaling pathways need further investigation. In this study, we identified a direct link between the light and auxin signaling pathways mediated by the auxin transcriptional repressor IAA3 and light-controlled PIF transcription factors in Arabidopsis. The gain-of-function mutation in IAA3 caused hyposensitivity to light, whereas disruption of IAA3 led to an elongated hypocotyl under different light intensity conditions, indicating that IAA3 is required in light regulated hypocotyl growth. Genetic studies showed that the function of IAA3 in hypocotyl elongation is dependent on PIFs. Our data further demonstrated that IAA3 interacts with PIFs in vitro and in vivo, and it attenuates the DNA binding activities of PIFs to the target genes. Moreover, IAA3 negatively regulates the expression of PIFs-dependent genes. Collectively, our study reveals an interplay mechanism of light and auxin on the regulation of hypocotyl growth, coordinated by the IAA3 and PIFs transcriptional regulatory module.

Statistical Optimization of Microcystis Growth and Microcystin Production in Natural Phytoplankton Community using Microcosm Bioassays

Eutrophication of freshwater lakes and reservoirs causing toxic cyanobacterial blooms has become a global health concern. Commonly used approaches of statistical modelling have not fully captured the complex response of cyanobacterial biomass and mi- crocystin concentration in response to stochastic variation of ambient conditions. This study applied statistically-based experimental design to screen out critical environmental factors, and to investigate the interactive effects of total nitrogen (TN), total phosphorus (TP), temperature (T) and light intensity (L) on Microcystis (MA) growth and microcystin (MC) production in the natural phytoplankton com- munity. A batch of central composite designed nutrient enrichment bioassays (CCD-NEBs) were conducted in an ambient-controlled microcosm based on pneumatic annular flume system. Second-order polynomial CCD regression models predicting MA density and MC concentration were established and validated. MC concentration was found positively related to MA dominance. The interactive effects of TN-TP and TN-L on both MA density and MC concentration were determined to be more significant than other factors. Ranges of the optimum TN/TP ratio for MA growth and MC production under various environmental conditions were defined as 9.5 ~ 10.2 and 9.9 ~ 10.4, respectively. The ranges of nutrient thresholds for MA density of 2.00 × 104 cells mL-1 and MC concentration of 1.0 μg L-1 under different temperature and light conditions were evaluated, respectively. This study revealed that nutrient thresholds for MA blooming events and cyanotoxins safety guideline were fluctuant under lake-dependant conditions of temperature and light intensity, and the optimum TN/TP mass ratios should be alerted for the eutrophication management of blooming formation and microcystin safety.