Intense White Light Research Articles

Effect of Change in Physical Parameters in the Paddling Response of the Common Backswimmer (Notonecta glauca)

This study investigates the impact of varying environmental factors, specifically temperature, pH, and white light intensity, on the paddling response of the common backswimmer, Notonecta glauca Linnaeus 1758 (Hemiptera: Notonectidae). The normal paddling rate was established at approximately 31.6 flaps per minute (FPM) under controlled conditions of 30°C, pH 6.8, and 50% sunlight exposure. When exposed to increased pH levels, the paddling rate exhibited a significant increase, rising by nearly 75% compared to the normal rate. Conversely, a decrease in pH led to an even greater enhancement in paddling activity, with a rise of approximately 90%. A notable response was observed under increased temperature, where the paddling rate surged by more than 2.6 times than expected, indicating a strong sensitivity to thermal changes. The most reduction in paddling activity occurred under low light intensity, with the rate plummeting to roughly 37% of the normal value. The findings underscore the susceptibility of N. glauca to variations in these key environmental parameters, particularly highlighting its heightened response to temperature fluctuations and low light conditions. The species of interest is observed as ecological sentinels and understanding its optimum limit of tolerance over fundamental physical parameters enables us to estimate the effect of climate change, environmental modifications and habitat alterations over the course of time.

Quantitative and qualitative response of saffron (Crocus sativus L.) to light intensity and nutrition in hydroponic cultivation

Despite the lengthy history of saffron cultivation in Iran, the reliance on traditional methods persists and falls short of meeting the growing market demand. Greenhouse technologies and hydroponic cultivation provide a solution by boosting stigma production, reducing labor, and addressing climatic challenges. An experiment was conducted in 2019 at the research greenhouses of Shahed University to examine the impact of artificial light intensities and nutrient concentrations on the quantitative and qualitative performance of saffron under hydroponic conditions. The study followed a split-plot scheme based on a completely randomized design. The main factor involved varying white light intensities (2, 4, 8, and 16 mol.m−2.d−1), while the subfactor included different Hoagland nutrient solution concentrations (0.75, 1.4, and 2.8 dS.m−1). Results showed that optimal conditions (light intensity up to 8 mol.m−2.d−1 and nutrient concentrations of 0.75 to 1.4 dS.m−1) led to a 3.64-fold increase in saffron flower yield and a 2.09-fold increase in stigma dry weight. These treatments also significantly enhanced crocin, picrocrocin, and safranal content, improving the spice’s quality by 5.43, 10.30, and 8.22 times, respectively. Light intensity significantly influenced the weight of the mother corm, while nutrient concentration did not, although consistent nutrition combined with higher light intensity increased the mother corm’s diameter. These findings highlight the effectiveness of using light intensities up to 8 mol.m−2.d−1 and Hoagland nutrient concentrations of 0.75 to 1.4 dS.m−1 for hydroponic saffron cultivation in greenhouses.

Effects of Different Light Conditions on Anatomical and Histological Features of Galls in Bacterial Gall Disease of Cerasus × yedoensis.

Cerasus × yedoensis (cherry 'Somei-yoshino' Fujino) is affected by bacterial gall disease caused by Pseudomonas syringae pv. cerasicola (PSC). C. × yedoensis is often infected with PSC under weak light intensity, which indicates that susceptibility of C. × yedoensis to PSC is affected by light. To evaluate the effects of white light intensity and different light qualities, white or blue, on bacterial gall disease development, we quantitatively assessed the anatomical and histological features of bacterial-inoculated sites on branches of 2-year-old potted C. × yedoensis seedlings grown under different light intensities and qualities. The stronger the white light intensity, the less severe the gall symptoms. Gall formation was suppressed more by blue than white light of the same intensity. The validity of a simple gall index for assessing gall development with the naked eye, via quantitative evaluation of gall shape by measuring gall height, width, and volume, showed that the gall index could be used as a practical method for on-site assessments of gall development. The ratio of degeneration area in the gall remained constant, suggesting the presence of some regulatory mechanism preventing PSC from affecting the entire gall within the plant. Microscopy showed that the gall tissue is composed primarily of callus cells and has voids containing gummy material that is exuded from cracks in the gall, and the periderm develops at the gall foot but not at the gall apex, so the cells at the gall apex were necrotic or collapsed.

Study on structural luminescence characteristics of a new Dy3+ activated white luminescent phosphor

A series of Y1-xGa1.5Al1.5(BO3)4: xDy3+ were prepared by a high-temperature solid-phase method. Rietveld refinement characterized the phase purity of the samples obtained, suggesting that the prepared phosphors were high-purity material phases. After synthesizing high purity phase, the luminescence mechanism is revealed, under 348 nm excitation in Y0.97Ga1.5Al1.5(BO3)4: 0.03Dy3+ phosphor, the samples have two characteristic peaks at 480 nm and 572 nm and the burst mechanism is dipole-dipole mechanism. The mechanism of luminescence and quenching is analyzed by analyzing the band structure, and the relationship between the band gap and thermal stability is explained. The prepared phosphor has a quantum efficiency of 51.22 % and exhibits intense white light emission. The thermal stability of the samples was characterized, and the phosphor could still achieve 88.20 % thermal stability at 423 K. Finally, the chromaticity coordinates of the Y1-xGa1.5Al1.5(BO3)4: xDy3+ phosphors all fall in the white-light region, with the color coordinates around (0.33, 0.33). By combining with the 365 nm chip and Y0.97Ga1.5Al1.5(BO3)4: 0.03Dy3+ phosphor, the W-led device with Ra = 68.3 and CCT = 6670 K was synthesized. Therefore, the Y0.97Ga1.5Al1.5(BO3)4: 0.03Dy3+ phosphor prepared in this experiment has some application value in the field of solid-state lighting.

Effects of UVA on Flavonol Accumulation in Ginkgo biloba

Ginkgo is an economic tree species with high medicinal value, and flavonols are its main medicinal components. This research was conducted to investigate the molecular mechanism underlying the influence of Ultraviolet A (UVA) treatment on the synthesis of ginkgo flavonols with the aim of increasing their content. Ginkgo full-sib hybrid offspring were used as test materials. The phenylalanine ammonialyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate: CoA ligase (4CL) enzyme activities, as well as flavonol contents, were measured under the same intensity of white light (300 μmol·m−2·s−1) with the addition of 20, 40, and 60 μmol·m−2·s−1 UVA separately after 20 days of treatment. The control check (CK) and treatment with the highest flavonol content were chosen for transcriptome sequencing analysis. The results showed that the PAL, C4H, and 4CL enzyme activities, as well as the flavonol and totalflavonol glycoside contents, of ginkgo hybrid progeny differed significantly under different UVA treatments. They showed a tendency to increase and then decrease, reaching a maximum value under UVA-4 (40 μmol·m−2·s−1 ultraviolet UVA light intensity) treatment. Ribonucleic acid (RNA) sequencing revealed the presence of 4165 genes with differential expression, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the metabolic pathways commonly enriched across all four comparison groups included ‘phenylpropanoid biosynthesis’, while the pathways commonly enriched in green-leaf ginkgo UVA-4 treatment (TL), yellow-leaf ginkgo mutant CK treatment (CKY), and green-leaf ginkgo CK treatment (CKL) were related to ‘flavonoid biosynthesis’. Treatment with UVA light led to the increased expression of PAL and 4CL enzymes in the phenylpropanoid biosynthesis pathway, as well as increased expression of chalcone synthase (CHS), Flavanone 3-hydroxylase (F3H), and flavonol synthase (FLS) enzymes in the flavonoid biosynthesis pathway, thereby promoting the synthesis of ginkgo flavonols. In summary, the use of 40 μmol·m−2·s−1 UVA treatment for 20 days significantly increased the flavonol content and the expression of related enzyme genes in ginkgo hybrid offspring, enhancing ginkgo flavonoids and increasing the medicinal value of ginkgo.

Visible emission studies by UV light conversion in (Dy3+/Tb3+) ions pair activated zinc-bismuth-barium borotellurite glasses for achieving intense green and white light

Both white light and green emission properties of (Dy3+/Tb3+) ions pair activated zinc-bismuth-barium borotellurite glasses were studied by ultraviolet light (UV:388 and 366 nm) conversion with a focus on down-conversion process. On the dependences of Tb3+ amounts with co-doping of Dy3+, densities of glasses, excitation, emission, area of the integration in percent, decay times, multipolar interactions, and most responsible photometric parameters are investigated in the current work. These co-activated glasses show a broad color production range (450–700 nm) covering of red (∼622 nm), green (∼545 nm), and blue (∼488 nm) colors under the stimulation of UV light wavelengths. The ratio from Yellow to blue emission was analyzed to study the site symmetry of Dy3+ surrounds. With 388 nm of UV radiation, the area of the integrated intensity under the green (Tb3+:545 nm) peak reaches a maximum of 87 %, while it falls under the yellow (Dy3+:575 nm) peak at about 13 %. The decay times of co-activated glasses were found in decreasing order, followed by fitting with a double-exponential function. The Reisfeld and Dexter's energy transfer mechanism confirmed the reduction in Dy3+ emission and its lifetime values through quadrupole-quadrupole interaction (f = 10). Moreover, photometric properties such as relative color temperatures, color coordinates, and color purity were also discussed and compared to discriminate the potentiality of the present fabricated glasses for use in both white light and green-emitting devices.

Top-down nanostructured multilayer MoS2 with atomically sharp edges for electrochemical hydrogen evolution reaction

Cost-efficient and readily scalable platinum-free electrocatalysts are crucial for a smooth transition to future renewable energy systems. Top-down activation of MoS2 promises the production of sustainable hydrogen evolution electrocatalysts from the Earth-abundant molybdenite ore. Here, the deterministic nanopatterning of multilayer MoS2 with numerous zigzag edges is explored as a pathway to enhance hydrogen evolution reaction (HER). Nanopatterned single-nanosheet MoS2 electrodes are assessed by two highly localized electrochemical techniques: selected area voltammetry (with lithography-defined regions of electrode-electrolyte contact) and Scanning ElectroChemical Microscopy (SECM). The nanopatterning effect is the most pronounced after prolonged electrochemical cycling in an acidic electrolyte. The electrocatalytic hydrogen evolution activity of edge-enriched electrodes is dramatically enhanced: the maximum electrochemical current density (jmax) achieved at -510 mV vs. reversible hydrogen electrode (mVRHE) is increased by two orders of magnitude, reaching >300 mA⋅cm−2. Both the η10 and η100 overpotentials are significantly reduced as well. Meanwhile, pristine MoS2 shows just ≈6 times jmax increase (≈30 mA⋅cm−2) after the very same cycling. The increased electrocatalytic activity comes with electrode morphology degradation, evidenced by ex-situ scanning electron microscopy. SECM directly visualizes stronger HER activity in the regions with densely located zigzag edges. Intense white light illumination significantly boosts HER on MoS2 electrodes due to the photo-enhanced MoS2 conductivity. These results improve the understanding and reveal the limitations of MoS2-based electrocatalytic water splitting.

The crosstalk of far-red energy and signaling defines the regulation of photosynthesis, growth, and flowering in tomatoes

This study investigated the effect of light intensity and signaling on the regulation of far-red (FR)-induced alteration in photosynthesis. The low (LL: 440 μmol m−2 s−1) and high (HL: 1135 μmol m−2 s−1) intensity of white light with or without FR (LLFR: 545 μmol m−2 s−1 including 115 μmol m−2 s−1; HLFR: 1254 μmol m−2 s−1 + 140 μmol m−2 s−1) was applied on the tomato cultivar (Solanum Lycopersicon cv. Moneymaker) and mutants of phytochrome A (phyA) and phytochrome B (phyB1, and phyB2). Both light intensity and FR affected plant morphological traits, leaf biomass, and flowering time. Irrespective of genotype, flowering was delayed by LLFR and accelerated by HLFR compared to the corresponding light intensity without FR. In LLFR, a reduced energy flux through the electron transfer chain along with a reduced energy dissipation per reaction center improved the maximum quantum yield of PSII, irrespective of genotype. HLFR increased net photosynthesis and gas exchange properties in a genotype-dependent manner. FR-dependent regulation of hormones was affected by light signaling. It appeared that PHYB affected the levels of abscisic acid and salicylic acid while PHYA took part in the regulation of CK in FR-exposed plants. Overall, light intensity and signaling of FR influenced plants' photosynthesis and growth by altering electron transport, gas exchange, and changes in the level of endogenous hormones.

Surface passivation of red-emitting fluoride phosphors by aminocarboxyl complexants to achieve high water-resistance for light-emitting diodes

Mn4+-activated fluoride phosphors are promising luminescent materials for use in phosphor-converted white-light-emitting diodes (wLEDs). However, poor water resistance in high humidity environment, one of critical drawbacks of this type of phosphors, has limited their practical applications. To address this issue, we developed a new facile strategy to passivate the surface of phosphors by in situ constructing a dual Mn4+-rare protective layer using well-known aminocarboxyl complexants with mild reducibility and strong complexation property. Ethylenediamine tetraacetic acid (EDTA) was taken as a representative for the research in detail, and a typical Mn4+-doped fluorosilicate phosphor K2SiF6:Mn4+ (KSFM) was selected to demonstrate the reliability of the proposed strategy. The surface passivation was achieved by simply dispersing KSFM in a saturated EDTA aqueous solution (KSFM-sEDTA) or a hydrofluoric acid solution containing a certain amount of EDTA (KSFM-EDTA), and then stirring for a short time at room temperature. The analysis results indicate that the dual Mn4+-rare surface layer is composed of a K2SiF6 matrix shell and an organic coating of residual EDTA and/or its related compounds, and the layer constructed by Method 2 is more significant than that by Method 1. Both the luminescence performance and the water resistance of the passivated KSFM were greatly enhanced while the luminescence characteristics remained unchanged. When the water-eroded KSFM was re-treated with EDTA, the luminescence was dramatically restored due to removal of the manganese hydrolysates and repair of the crystal surface defects. The wLEDs assembled with KSFM-EDTA and KSFM-sEDTA phosphor exhibited intense white light with high luminous efficiency (LE, 170.61 lm/W and 162.51 lm/W), high color rendering index (CRI, 88.3 and 85.9), and low correlated color temperature (CCT, 3680 K and 3805 K), respectively. More importantly, the fabricated wLEDs retained high LE (90.6% and 88.6%) and no remarkable changes of CRI and CCT values after being aged at high temperature and humidity (85 °C, 85%) for 550 h, which are more superior to the wLED assembled with the pristine KSFM.

Recurrently Propagating Intensity Disturbances along Polar Plumes Observed in White Light and Extreme Ultraviolet

We study properties of intensity disturbances along polar coronal rays that are associated with plumes below. For this, we draw azimuth–time images of extreme ultraviolet (EUV) emission of 171 Å band observed by the SDO/AIA and white light (WL) observed by the SOHO/LASCO C2 in 2020 July. From the azimuth–time image, we define two tracks in which the EUV intensities were recurrently enhanced during two weeks. The two EUV tracks are rooted at 78.°8 and 81.°4 latitudes, but their projected azimuth angles are changed with time as the Sun rotates. Coherent WL tracks at different altitudes are determined by scaling the azimuth angles of the EUV tracks, accounting for the effect of inclination of coronal rays. From this, we construct time–distance images of WL intensities along WL tracks, whose projected azimuth angle changes along time and altitude, but the intensities are correlated with the EUV intensities measured below. The time–distance images of WL show repeated and inclined intensity features. The propagation speeds in the altitude range 2.3–6 solar radii are calculated to be 159 ± 8 km s−1 and 300 ± 24 km s−1. The EUV and WL intensities are found to be coherent at 1–2 day periods. It is also found that dynamic burst events along the EUV track are responsible for the enhanced emission. We conclude that the variation of the WL intensity along the polar coronal rays is related with the evolution of the EUV intensity below.

Illumination Effects on Bacteriorhodopsin Accumulation in Archaeon Halobacterium Halobium

Highlights Effects of varying illumination conditions, including light intensity, light color, and illumination pattern on archaeon Halobacterium halobium growth and bacteriorhodopsin (BR) accumulation were first evaluated. LED green light was much more energy-efficient than the red and blue lights in this research. If energy consumption was not a concern, LED blue and red lights (or their combinations) were more effective for cell growth and BR accumulation, respectively, with a similar light intensity. Abstract. This study was to understand the effect of LED light intensity, color, and illumination pattern on the growth of and bacteriorhodopsin (BR) accumulation in archaeon Halobacterium halobium. Experimental results showed that archaeon growth and BR content increased with increasing white light intensity. Green and white LED lights were found to be the most effective for archaeon growth and BR accumulation; here, effectiveness is defined based on photons shined on the bioreactor. The 12-h light/12-h dark cycle illumination pattern resulted in longer lag phase but achieved higher final cell growth and BR accumulation than continuous white light or an instant flash of light/dark illumination. The fade pattern that had smooth transitioning among green, blue, and red lights was better than the jump pattern without transitioning. The highest cell dry weight and BR content of H. halobium were 1.84 g l-1 and 11.76 mg l-1, respectively, under 29.85 µmol/m2s LED white light illumination. The green LED light of 1.39 µmol/m2s had the highest energy-specific conversion effectiveness and saved energy consumption by 84 and 87% per cell biomass and BR dry weight, respectively, compared to the worst case of LED white light of 29.85 µmol/m2s. Keywords: Archaeon, Bacteriorhodopsin, Halobacterium halobium, Illumination pattern, LED light, Light color.

Optimizing the performance of (Sb0.2Sn0.8)0.5(S0.9Se0.1)0.5 crystal-based self-powered photodetectors

The need to develop electronic systems capable of functioning without an external power source is an utmost priority, especially in the pursuit of self-powered photodetection. Through the direct vapor transport (DVT) method, we have synthesized a single crystal of the quaternary compound (Sb0.2Sn0.8)0.5(S0.9Se0.1)0.5 for self-driven photodetectors. The crystal's elemental composition was ascertained via energy-dispersive X-ray analysis (EDX), along with Field emission scanning electron microscopy (FESEM) provided insight into its surface morphology. The orthorhombic crystal system of the grown sample has been validated by a powder X-ray diffractometer (XRD). The regular spot pattern of SAED and the well-defined sharp peaks observed in the XRD graph collectively indicate the crystal's pronounced crystalline quality. The lattice parameters closely resemble the reported data. A UV–VIS-NIR spectrometer was utilized to deduce a direct optical band gap of 1.49 eV. Raman spectroscopy was used to examine different phonon modes. We analyzed its pulsed photo response by subjecting the grown crystal to different wavelengths and varying intensities of white light at self-biased mode and by applying 1 V bias. Our analysis enabled us to determine favourable photodetection parameters.

Comparative investigation on luminescence properties of red-emitting KLiSnF6:Mn4+ phosphors and the fluorescent sheet for high-power LEDs

New red-emitting phosphors KLiSnF6:xMn4+ (KLSFM, x = 4%, 6%, 8%, 10%, and 12%) for LED lighting were synthesized by an ion-exchange method at room temperature. Among these phosphors, the KLSFM (8 mol%) sample exhibits the strongest excitation in the blue region and emission in the red region. The corresponding translucent fluorescent sheet prepared by the pressure method shows similar luminescent properties which are identical to the powders with the strongest absorption at 467 nm and narrow emission around 632 nm. The fluorescent sheet offers high transmittance in UV–Vis region (close to 100% beyond 550 nm) and better thermal stability and color stability. For comparison, the white pc-LEDs based on the KLSFM (8 mol%) phosphor and fluorescent sheet all emit intense white light with an ideal color rendering index (CRI >93) and a good correlated color temperature (CCT <3500 K). However, the white pc-LED based on the fluorescent sheet have more advantage in application for high-power devices. Working at 200 mA, the LED fabricated with the translucent sheet still keeps excellent performance with a high CRI of 90.1 and a low CCT of 3874 K. The working temperature for this device is only 90 °C after working for 40 min, which is lower than that of the device with the KLSFM (8 mol%) powder, furtherly proving that the translucent sheet has excellent heat dispersion. Therefore, the KLSFM (8 mol%) translucent sheet could be used for high-power pc-LEDs as a red component.

Red-Light Transmittance Changes in Variegated Pelargonium zonale-Diurnal Variation in Chloroplast Movement and Photosystem II Efficiency.

Chloroplast movement rapidly ameliorates the effects of suboptimal light intensity by accumulating along the periclinal cell walls, as well as the effects of excess light by shifting to the anticlinal cell walls. These acclimation responses are triggered by phototropins located at the plasma membrane and chloroplast envelope. Here, we used a recently developed non-invasive system sensitive to very small changes in red light leaf transmittance to perform long-term continuous measurements of dark-light transitions. As a model system, we used variegated Pelargonium zonale leaves containing green sectors (GS) with fully developed chloroplasts and achlorophyllous, white sectors (WS) with undifferentiated plastids, and higher phototropin expression levels. We observed biphasic changes in the red-light transmittance and oscillations triggered by medium intensities of white light, described by a transient peak preceded by a constant decrease in transmittance level. A slight change in red-light transmittance was recorded even in WS. Furthermore, the chloroplast position at lower light intensities affected the rapid light curves, while high light intensity decreased saturated electron transport, maximum quantum efficiency of photosystem II, and increased non-photochemical quenching of chlorophyll fluorescence and epidermal flavonoids. Our results extend the knowledge of light-dependent chloroplast movements and thus contribute to a better understanding of their role in regulating photosynthesis under fluctuating light conditions.

Poster Session: Observations and Implications of Temporary Erythropsia in a Color-Normal Observer.

Erythropsia (red vision) is characterized by the reddish or pinkish appearance of surfaces that normally appear achromatic. Erythropsia has been observed historically by people whose retinas were exposed to ultraviolet (UV) light (e.g., aphakes or pseudophakes implanted with unfiltered intraocular lenses). Erythropsia is not fully understood, but has been thought to be related to photochemical damage to short-wavelength (S) cones. Erythropsia can also occur in normal phakic eyes during intense white light adaptation. When I stare at the sunlit white siding on the southern wall of my house, after several seconds, the color changes from white to a brilliant magenta, with the central 1-2º of visual angle spared. All details in the siding fade except for the spared center. In another 10-20 seconds, the magenta turns to bluish cyan, and the previously invisible details reappear with exaggerated contrast. These observations are reminiscent of the color of S-cone increments on white adapting fields (Drum & Sternheim (2005) JOSA A: 22, 2107-19). S cones are insensitive relative to M and L cones on dim backgrounds, but they do not light-adapt like M and L cones and become relatively more sensitive at moderate adapting levels. At still higher adapting levels, S cones saturate (become unresponsive) leaving the increment a tritanopic cyan. The present observations imply that S cones initially fail to adapt to a bright white field, but then saturate, leaving the observer tritanopic.

Quantity and Quality of Light on Growth and Pigment Content of Dunaliella sp. and Anabaena sp. Cultures and the Use of Their Absorption Spectra as a Proxy Method for Assessment

(1) Background: As microalgae cultures are affected by the quantity and quality of light, I explored this for two species. Additionally, I introduced a novel easy and economical way for the growers to easily and economically ascertain continuously with satisfactory accuracy the quantitative and qualitative status of their culture using absorption spectra. (2) Methods: The locally isolated chlorophyte Dunaliella sp. and the cyanobacterium Anabaena sp. were cultured in small volumes with two intensities of white light (2000 and 8000 lux) and with green, blue and red light, and the increase in their biomass and pigments was studied. Pigment analyses, continuous recordings of absorption spectra and calibration curves were used. (3) Results: The intensity of 8000 lux of white light yielded the highest increase in biomass, chlorophylls and carotenoids in Dunaliella sp., and the same was found for green and blue light, while 2000 lux and green light caused the greatest increase in biomass and phycocyanin in Anabaena sp. From the absorption spectra, the evolution of the pigment content can be estimated, and both pigments and biomass are correlated very strongly with those extracted from the spectra absorption of 750 nm. (4) Conclusions: The use of absorption spectra as an easy, fast and economical method can be a useful tool for a good approximation of the state of the microalgae culture. This is clearly shown when the spectra of the cultures under different light intensities and colors are compared having a catalytic effect on the level of the pigments leading to the increase in carotenoids and phycocyanin of the green light.

Evaluation of secondary sexual dimorphism of the dioecious Amaranthus palmeri under abiotic stress

The evolution of secondary sex-specific traits of dioecious species under abiotic stress conditions has received limited research, especially in the case of Amaranthus palmeri, a fast adapting and highly competing plant. Here, we have examined the interactive effects of abiotic stress on mineral accumulation, chlorophyll a and b content, and the operating capacity of Photosystem II (PSII) in both male and female A. palmeri plants grown under three different intensities of white light, and under N, K or P deficiency. Mineral profiling of the leaves and stems (with inflorescence) highlighted intra- and intersexual differences in their accumulation pattern and mineral associations. Chlorophyll a and chlorophyll b were different between the male and the female plants, being slightly lower in the latter, at high light intensity towards maturity, or under K or P deficiency. Further, slight, although statistically significant differences were recorded in the chlorophyll a/b ratio, which was lower at the higher light intensity in the female, over that in the male, plants towards maturity. Chlorophyll fluorescence parameters, i.e., steady state and maximum fluorescence increased under high light intensity, whereas the PSII operating efficiency decreased in the female plants, indicating reduced PSII capacity. Sex-specific differences in A. palmeri showed a differential response to stressful conditions because of differences in their ontogeny and physiology, and possibly due to the cost of reproduction. We suggest that the breeding system of dioecious species has weaknesses that can be used for the ecological management of dioecious weeds without relying on the use of herbicides.

Kajian Penggunaan LED pada Pertumbuhan Tanaman Kailan dengan Sistem Hidroponik Dalam Ruangan

The use of LED (Light Emitting Diode) in indoor hydroponic systems can optimize the process of photosynthesis in plants. This can be a replacement of sunlight during plant growth. This study aims to examine the treatment of LED light intensity and duration of irradiation on the vegetative growth of kailan (Brassica oleracea var. alboglabra L) in indoor hydroponic systems. This experimental study consisted of 5 treatments: exposure to white (A1) and blue (A2) LED lights, exposure time of 16 hours (B1) and 20 hours (B2) and sunlight (K0) as a control in a greenhouse. Treatment with LED lights placed in the growth chamber. Treatment consisted of 4 replicates with a total of 20 plants. The results showed that the white LED light intensity and 20 hours of irradiation time were better than other treatments including plant height, stem diameter, leaf width, leaf length, number of leaves, fresh weight, root weight and water efficiency.

Highly Responsive Al/PTB7/Si/Al Vertical Structure-Based White Light Photodetector Using FTM Method

This article reports a p-type Poly [[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl) carbonyl] thieno [3,4-b] thiophenediyl ]] (PTB7) thin film based Al/PTB7/Si/Al vertical structure for white light detection application. The thin film of PTB7 polymer was deposited via a low-cost and facile floating-film transfer method (FTM). The morphology of the PTB7 film is analyzed by tapping mode Atomic Force Microscopy (AFM) which gives an average surface roughness as ~0.703 nm. The maximum responsivity and detectivity of the fabricated device were obtained as ~146.13 mA/W and ~4.137 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> Jones at ~0.228 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> white light intensity under a reverse bias of -2 V. The rise/fall time of the fabricated sensing device was measured as ~0.016/~0.112 s respectively.

Laser-Induced Tunable White Light Emission in Yb3+/Er3+/Tm3+ Ion-Doped La2Ti2O7

A series of compounds with the general formula (La1−xREx)2Ti2O7 (x = 0.005, 0.015, and 0.025) doped with Yb3+, Er3+, and Tm3+ rare Earth ions were prepared by the traditional solid-state reaction at 1350 °C for 24 h. The X-ray powder diffraction technique, high-resolution transmission electron microscopy, and photoluminescence spectroscopy technique were used to characterize the structure and optical properties of the compounds. All compounds showed a single-phase orthorhombic structure with a space group Pna2 1, as confirmed by JCPDS (Cart No: 01-070-1690). The La1.9Yb0.04Er0.01Tm0.05 Ti2O7 nanocrystals exhibited intense tunable white light luminescence signals in the full spectrum, and green and blue emissions were predominant in the Yb3+/Er3+− and Yb3+/Tm3+-doped titanates, respectively. In this study, the influence of concentration and excitation power on the upconversion luminescence, color, and calculated laser-power-induced heating performance of La2Ti2O7 nanophosphors were investigated at room temperature.