Effect of Light Intensity on Schottky Barrier Widths and I-V Characteristics of Polymer Heterojunction Photodiodes

2011 ◽  
Vol 1359 ◽  
Author(s):  
Ali Bilge Guvenc ◽  
Cengiz Ozkan ◽  
Mihrimah Ozkan

ABSTRACTThe Schottky barriers that forms on the interface between aluminum and organic semiconductor of polymer heterojunction photodiodes based on poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methylester blend, has been investigated according to Mott-Schottky curves. We focused on the effect of light intensity on the Schottky barrier widths and I-V characteristics of the devices. Comparison of the mathematical models and experimental data measured under different light intensities indicate a dependency of Schottky barrier to the light intensity.

Author(s):  
Yuzuru Ikeda ◽  
Kingo Ito ◽  
Gen Matsumoto

The effect of light intensity on the course of embryonic development of squid (Heterololigo bleekeri) was examined. Heterololigo bleekeri embryos at an early stage were incubated in the egg cases under six to seven gradients of light intensities which varied from constant darkness to intensive light >1000 lx (12L:12D for all experimental groups except for the constant darkness group). Duration of hatching in every experimental group ranged from seven to 15 days with a peak for ≈30–50% of total number of hatchlings. However, there were no particular relationships between light intensities and duration of embryonic development, duration of hatching, number of hatchlings at hatching peak, and body size of hatchlings. In all groups, body size of hatchlings increased up to seven days post-hatching and thereafter did not change remarkably. Just after hatching, strongly positive photo taxis was observed for H. bleekeri


1994 ◽  
Vol 45 (1) ◽  
pp. 43 ◽  
Author(s):  
TJ Wassenberg ◽  
BJ Hill

The emergence behaviour of eight species of commercial prawns (between 25.0 and 30.0 mm carapace length) was studied in the laboratory. All except Penaeus merguiensis were nocturnal: they emerged from the substratum in the evening when the light was dimmed and buried themselves in the morning, usually before dawn. P. merguiensis generally remained on the substratum during the day. The species can be grouped on the basis of their behaviour: the first group (P. plebejus and P. latisulcatus) was most sensitive to light, the second group (P. semisulcatus, Metapenaeus ensis, P. esculentus, M. endeavouri and M. bennettae) was less sensitive to light, and the third (P. merguiensis) was least sensitive to light. To find out what triggered emergence, two species (P. esculentus and P. plebejus) were exposed to different rates of light dimming at dusk. Both species responded to absolute light intensity, but the response of P. plebejus was affected by the rate of change of light intensity. The different responses of the species to different light intensities explains some of the differences in catchability in a multi-species prawn fishery.


1999 ◽  
Vol 47 (4) ◽  
pp. 231-236
Author(s):  
Shimon Lavee ◽  
Elizabeth Van Volkenburgh ◽  
Robert Cleland E.

The effect of light intensity on primary bean leaf unfolding and elongation was studied with intact and excised 10-day-old plants grown under red light. Continuous light of 40 μmol; m−2S−1 was enough to induce maximal leaf expansion both on intact and excised bean plants. Lower light intensities had a partial effect. The growth rate during the first 24 h in light was linearly related to light intensity up to 130 μmol; m−2S−1, although this light intensity was already supra-optimal for final leaf size. The minimal amount of light energy needed for full leaf expansion was about 15 mol photons m−2. The mode of light application, level of intensity, and irradiance duration were not critical when the total energy requirement was fulfilled. Under insufficient light applications for full leaf expansion, interrupted irradiance and longer low light intensity application induced leaf elongation more efficiently. Generally, the effect of different white light intensities on primary bean leaf expansion was the same on both intact and excised red-light-grown plants.


2019 ◽  
Author(s):  
Kalpana Arambam ◽  
Pradyut Biswas ◽  
Soibam Khogen Singh ◽  
A. B. Patel ◽  
Alok Kumar Jena ◽  
...  

AbstractTwo sequential indoor rearing trials each of 21 days duration were conducted to investigate the effect of light intensity and photoperiod respectively on the growth and survival of Ompok bimaculatus larvae. In first trial, five different light intensities viz. 0, 300, 500, 900, 1200 lx were applied randomly to 800 larvae (0.003 g; 0.51 cm) stocked in triplicate following a completely randomized design into aquarium (30.0 x 15.0 x 15.0 cm) tanks. Sequentially, in second trial, five photoperiod cycles (light: dark, L: D) namely, 24L: 0D, 16L: 8D, 12L: 12D, 8L: 16D and 0L: 24D in combination with the best performing light intensity (300 lx) as observed from the first trial were employed in triplicates in similar set up. From the first trial, significantly higher survival was observed in 0 and 300 lx, whereas growth was highest in 900 lx (P < 0.05). In the second trial, survival was higher in continuous darkness (0L: 24D), whereas, maximum growth was recorded in 24L: 0D and 16L: 8D groups (P < 0.05). Performance index (PI) showed no significant difference (P > 0.05) among 0 and 300 lx light intensities, but were reduced at higher light intensities. The lowest PI was found in 12L: 12D and 8L: 16D condition but did not have any effect in other photoperiod cycles. Overall, from the present study it can be concluded that growth of the larvae is found to be higher in higher light intensity (900lx) and longer photoperiodic cycles (24L: 0D and 16L: 8D), however, better survival was recorded in total dark conditions suggesting that continuous dark condition is recommended for better hatchery performance of the larvae.


1983 ◽  
Vol 38 (7-8) ◽  
pp. 544-548 ◽  
Author(s):  
J. M. Steyns ◽  
G. van Nigtevecht ◽  
G. J. Niemann ◽  
J. v. Brederode

Two isovitexin glycosides have been found in the cotyledons and foliage leaves of Sitene pratensis plants that are unable to glycosylate isovitexin in their petals (genotype gg glgl fgfg). The glycosides (isovitexin 7-O-galactoside and isovitexin 7-O-galactose 2″-O-arabinoside) were present only in the lower leaves: leaves produced later in the development of the flower stem accumulated only the aglycon isovitexin. The transition in the flavone composition during the ontogeny of the plants could be influenced by light intensity. In plants grown at low light intensity, glycoside production continued until a higher leaf pair number than in plants grown at higher light intensities. However, the effect of light intensity is indirect: the transition in the flavone composition is correlated with the transition from rosette leaves to stem leaves. The presence of the 7-O-galactosides in cotyledons and rosette leaves suggests that in addition to the g, gl and fg loci, there are further glycosylating loci which are not expressed in stem leaves and petals.


1959 ◽  
Vol 7 (3) ◽  
pp. 252 ◽  
Author(s):  
RL Bieleski

A method for determining the effect of light on seedling distribution in the field is described. It can be applied when seedling frequencies are as low as 1/m2. The frequency distribution of light intensities occupied by seedlings in a quadrat is compared with the frequency distribution of light intensities measured on a grid in the quadrat. This method was used to study the effect of light intensity on the establishment of two New Zealand gymnosperms, kauri (Agathis australis) and Phyllocladus trichomanoides, in the nursery community, a semimature Leptospermum scoparium – L. ericoides associes. Kauri and Phyllocladus did not occur at light intensities below 0.015 and 0.018 full daylight respectively. This limitation appeared to be due to the low light intensity presumably limiting photosynthesis. Kauri, but not Phyllocladus, also showed a high light intensity limit, at 0.30 full daylight, above which seedlings did not establish. Reasons are given for considering this as an indirect effect, probably through related solar heating affecting soil temperature or moisture. The optimal light intensity for kauri and Phyllocladus seedling establishment was close to the modal light intensity under the Leptospermum community: Leptospermum spp. were incapable of regenerating under their own cover. These two reasons appear to explain the suitability of the Leptospermum community as a nurse crop for the two conifer seedling species.


1998 ◽  
Vol 49 (5) ◽  
pp. 363 ◽  
Author(s):  
Patricia M. Pankhurst ◽  
Pollyanna E. Hilder

This study investigates the influence of light intensity on feeding of striped trumpeter larvae, correlating feeding responses with changes in morphology of the retina during growth. A pigmented single-cone retina had differentiated one day before first feeding, and rod precursor cells and double cones were visible in the retina on the 23rd, and 25th day after hatching, respectively. Feeding performance at four light intensities (0, 1, 30, 150 and 700 lux), revealed that striped trumpeter larvae are primarily dependent on vision, a light-dependent behaviour, to feed. The youngest larvae tested (15, 18 and 19 days of age) showed a poor feeding response at 1 lux (range 2–10%), but a 98–100% feeding response at 30, 50 and 700 lux. By 28 days of age, feeding behaviour had changed significantly, with 52% of fish now feeding at 1 lux, 100% of fish feeding at the intermediate light intensities of 30 and 150 lux, and only 62% of fish feeding at 700 lux. The apparent increased photopic sensitivity in 28-day-old fish may reflect increased areas for photon capture provided by double cones, or may reflect ontogenetic changes in cone spectral sensitivity.


2017 ◽  
Vol 16 (1) ◽  
pp. 15
Author(s):  
Muhammad Fakhri ◽  
Nasrullah Bai Arifin ◽  
Anik Martina Hariati ◽  
Ating Yuniarti

<p class="Pa3"><strong>ABSTRACT </strong></p><p> </p><p class="Pa5"><em>Nannochloropsis </em>sp. has been identified as sources of live feed and pigment in aquaculture. To increase the production, the optimal environmental conditions for microalgae are required. Light intensity is one of the important factors that significantly affects the biomass and pigment of microalgae. The study aimed to determine the effect of light intensity (1,500; 3,000; and 4,500 lux) on growth, biomass production, chlorophyll-a, and carotenoid content of <em>Nannochloropsis </em>sp. strain BJ17. The results showed that different light intensities significantly affected the growth, biomass, chlorophyll-a and carotenoid contents of <em>Nannochloropsis </em>sp. strain BJ17. Increasing light intensity resulted in the increase of the growth rate, biomass, chlorophyll-a, and carotenoid contents of <em>Nannochloropsis </em>sp. strain BJ17. The cell achieved the highest specific growth rate of 1.729 %/day and the cell concentration of 43.333×106 cell/mL at a light intensity of 4,500 lux. The highest chlorophyll-a and carotenoid concentrations of algae were obtained at 4,500 lux (8.304 μg/mL and 3.892 μg/mL, respectively). This study suggested that increasing light intensity led to the increase in the growth, biomass, chlorophyll-a, and carotenoid content of <em>Nannochloropsis </em>sp. strain BJ17.</p><p> </p><p class="Pa5">Keywords: carotenoid, chlorophyll, biomass, growth rate, light intensity</p><p> </p><p> </p><p class="Pa3"><strong>ABSTRAK </strong></p><p> </p><p class="Pa5"><em>Nannochloropsis </em>sp. diketahui sebagai sumber pakan alami dan pigmen pada budidaya perikanan. Budidaya pada kondisi lingkungan yang optimal diperlukan untuk meningkatkan produksi mikroalga. Intensitas cahaya merupakan salah satu faktor esensial yang secara signifikan mempengaruhi biomassa dan pigmen mikroalga. Tujuan penelitian ini adalah untuk menentukan pengaruh intensitas cahaya yang berbeda (1.500, 3.000, and 4.500 lux) terhadap pertumbuhan, produksi biomassa, klorofil-a, dan karotenoid <em>Nannochloropsis </em>sp. strain BJ17. Hasil menunjukkan bahwa intensitas cahaya yang berbeda berpengaruh secara signifikan terhadap pertumbuhan, biomassa dan klorofil-a dan karotenoid <em>Nannochloropsis </em>sp. strain BJ17. Semakin tinggi intensitas cahaya maka laju pertumbuhan, biomassa, kandungan klorofil-a dan total karotenoid <em>Nannochloropsis </em>sp. strain BJ17 semakin tinggi. Laju pertumbuhan spesifik tertinggi 1,729%/hari dan konsentrasi sel maksimum tertinggi 43,333×106 sel/mL dihasilkan pada intensitas cahaya 4.500 lux. Konsentrasi klorofil-a (8,304 μg/mL) dan karotenoid (3,892 μg/mL) tertinggi juga diperoleh pada intensitas cahaya 4.500 lux. Studi ini menunjukkan bahwa peningkatan intensitas cahaya berperan dalam meningkatkan pertumbuhan, produksi biomassa, klorofil-a, dan karotenoid <em>Nannochloropsis </em>sp. strain BJ17.</p><p> </p><p>Kata kunci: karotenoid, klorofil, biomassa, pertumbuhan, intensitas cahaya</p>


Author(s):  
Brandon Ross ◽  
Robert William McClelland Pott

Photosynthetic bacteria can be useful biotechnological tools – they produce a variety of valuable products, including high purity hydrogen, and can simultaneously treat recalcitrant wastewaters. However, while photobioreactors have been designed and modelled for photosynthetic algae and cyanobacteria, there has been less work on understanding the effect of light in photosynthetic bacterial fermentations. In order to design photobioreactors, and processes using these organisms, robust models of light penetration, utilisation and conversion are needed. This article uses experimental data from a tubular photobioreactor designed to focus in on light intensity effects, to model the effect of light intensity on the growth of Rhodopseudomonas palustris, a model photosynthetic bacterium. The work demonstrates that growth is controlled by light intensity, and that this organism does experience photoinhibition above 600 W/m2, which has implications for outdoor applications. Further, the work presents a model for light penetration in circular photobioreactors, which tends to be the most common geometry. The work extends the modelling tools for these organisms, and will allow for better photobioreactor design, and the integration of modelling tools in designing processes which use photosynthetic bacteria.


1971 ◽  
Vol 49 (1) ◽  
pp. 21-25 ◽  
Author(s):  
Praim N. Sood ◽  
W. E. Sackston

Light intensity from 2200 to 43 000 lux during production of urediospores of Puccinia helianthi had little influence on germinability of fresh spores. The higher light intensities had an adverse effect on germinability of spores stored at −16 °C for 2 months. Daylength had little consistent effect on germinability of fresh or stored spores. Spores produced at day temperatures of 16, 21, and 27 °C showed no effect of temperature on germinability when fresh. After 2 months storage at −16 °C germination was highest for spores produced at 21°. Spores of races 1 and 3 germinated well after 1218 days of storage at −16°, and a small percentage germinated after storage at 4 °C. Races 2 and 4 germinated well after 1136 days storage at −16 and 4 °C. Races 2 and 4 survived longer than races 1 and 3 at 30° and at 23 °C, but not at 13 °C. Race 3 appeared more susceptible than race 1 to effects of light, temperature, and storage.


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