Light Intensity Conditions Research Articles

Effects of light intensity on growth and content of active components of Uncaria rhynchophyll

The aim of this study was to study the effects of different light intensity on the growth,biomass accumulation and distribution,chlorophyll content and effective components of Uncaria rhynchophylla seedlings,and explore the suitable light intensity conditions for artificial cultivation of U. rhynchophylla seedlings. Three-year-old U. rhynchophylla seedlings were used as experimental materials. Four light intensity levels( 100%,70%-75%,30%-35%,5%-10%) were set up with different layers of black shading net. With the decrease of light intensity,the results showed that the plant height,basal diameter and biomass( root,stem,leaf and hook) of U.rhynchophylla seedlings exhibited the trend of " increase-decrease". Under 70%-75% light intensity,the plant height,basal diameter,biomass( root,stem,leaf,hook) of U. rhynchophylla seedlings were significantly higher than those of other treatments( P< 0. 05);under 5%-10% light intensity,the plant height,basal diameter and biomass( root,hook) of U. rhynchophylla seedlings were significantly lower than those of other treatments( P<0. 05). With the decrease of light intensity,the chlorophyll content of U. rhynchophylla seedlings increased gradually: under 100% light intensity,the chlorophyll content of U. rhynchophylla seedlings were the smallest,while under 100% light intensity,its chlorophyll content was the highest. With the decrease of light intensity,the contents of rhynchophylline and isorhynchophylline in different organs of U. rhynchophylla seedlings varied: under 30%-35% light intensity,the contents of rhynchophylline and isorhynchophylline in hooks and rhynchophylline content in stems were the highest; under 5%-10% light intensity,the contents of rhynchophylline and isorhynchophylline in leaves and stems of U. rhynchophylla were the highest. In conclusion,70%-75% light intensity is suitable for seedling growth and biomass accumulation,and 30%-35% light intensity is suitable for the accumulation of effective components in U. rhynchophylla seedlings.

Heads-Up 3D Surgery under Low Light Intensity Conditions: New High-Sensitivity HD Camera for Ophthalmological Microscopes.

Purpose To determine the feasibility of performing intraocular surgeries in a heads-up position with low illuminance conditions by observing a display of the surgical field created by a three-dimensional imaging (3D) system. Methods Seventy-four eyes of 56 patients underwent cataract surgery (72 eyes) with the heads-up 3D surgery system; 60 eyes with cataract surgery alone, 7 eyes with combined cataract and glaucoma microdevice implant surgery, 5 eyes with combined cataract and vitrectomy surgery, and two eyes with vitrectomy surgery alone were studied. The illuminance from the surgical microscope was set to be dimmer (Leica M822F40 main light 2%; otto-flex 6%) than the usual setting to minimize the discomfort and glare for the patient. The surgeries were performed under topical anesthesia. The luminance of the images observed through the eyepieces of the operating microscope and the image of a 3D system created by a high-sensitivity sensor Exmor R 3CMOS HD camera (Sony MCC-1000MD) were measured. Results All surgeries were completed without any complications under the low illumination conditions. The surgical field on the display monitor was created by a 3D system using a high-sensitivity sensor camera and was observed in a heads-up position. The patients did not report any intolerable discomfort or glare during the surgery. Cataract surgeries were performed with a good view of the surgical field under the extremely low illumination from the surgical microscope. The high-sensitivity sensors and electronic amplifications of the image signals made the surgical field brighter and allowed the surgeon to perform the surgery confidently and safely. Conclusions Heads-up, 3D-assisted intraocular surgeries can be performed safely and efficiently with low illuminance of the surgical field. This trial is registered with UMIN000037838.

CuAlMnV shape memory alloy thin film based photosensitive diode

In the present work, the polycrystalline quaternary shape memory alloy (SMA) using composition of Cu-10.24 Al-3.13 Mn-0.41 V (wt%) was prepared with arc melting technique. The produced SMA was characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). In order to fabricate the Schottky diode, the SMA was utilized as a Schottky contact on n-Si. The admittance (Y = G + iωC) measurements were performed at different frequencies while the current-voltage (I–V) measurements of the prepared diode were performed at different light intensity conditions. The reverse bias current measured under illumination was found to be greater than the condition of dark. The obtained results approve that the diode displays a photoconducting behavior. The electrical parameters of diode were calculated from I–V data. Besides, the frequency impacts on the capacitance and conductance characteristics with regards to voltage were investigated. The experiments suggest that the fabricated diode could be chosen in the applications of the optoelectronic devices.

Evaluation of the interaction of temperature and light intensity on the growth of Phaeodactylum tricornutum: Kinetic modeling and optimization

In this study, the effects of two highly variable factors, temperature ranging from 10–35 °C and light intensity from 98–1289 μmol m−2s-1, on the specific growth rate, μ, of a diatom, Phaeodactylum tricornutum, at a constant aeration rate of 3000 cm3 min-1 were elucidated. The choice of the adequate kinetic models describing the growth related to temperature and light intensity resulted in rapid determination of optimum growth conditions. Ratkowsky’s square root model and Monod-type model were assessed as the most suitable expressions among the three temperature- and eight light intensity-dependent models, respectively, presenting the highest adjusted R2 and smallest average relative deviation (ARD) values by means of nonlinear least squares method. Also, among the kinetic model approaches utilized to verify the combined effects of temperature and light intensity, the temperature-dependent Ratkowsky model in conjunction with the Monod-type expression with the smallest ARD value (4.19 %) and a high adjusted R2 (0.9775) exhibited the best surface fit. The optimum cultivation temperature and light intensity conditions for the achieving maximum specific growth rate of P. tricornutum were determined as 21 °C and 496 μmol m−2s-1, respectively, by the help of the Central Composite Design (CCD) of the Response Surface Methodology (RSM).

Nitric Oxide Is Involved in the Regulation of the Ascorbate-Glutathione Cycle Induced by the Appropriate Ammonium: Nitrate to Mitigate Low Light Stress in Brassica pekinensis.

Low light intensity is common in northern China due to fog or haze, and causes stress for crop plants. To solve the problem of low light intensity stress on the growth and development of vegetable crops in China, new cropping strategies must be developed. We previously showed that an appropriate ratio of ammonium and nitrate (NH4+:NO3−) can alleviate the effect of low light stress on plants, although it is not clear what mechanism is involved in this alleviation. We propose the hypothesis that an appropriate ammonium/nitrate ratio (10:90) can induce NO synthesis to regulate the AsA-GSH cycle in mini Chinese cabbage seedlings under low light intensity. To test the hypothesis, we conducted a series of hydroponic experiments. The results indicated that, under low light intensity conditions, appropriate NH4+:NO3− (N, NH4+:NO3− = 10:90) decreased the contents of malondialdehyde (MDA), hydrogen peroxide (H2O2), and superoxide anion (O2−) in leaves compared with nitrate treatment. Exogenous nitric oxide (SNP) had the same effects on MDA, H2O2, and O2−. However, with the addition of a NO scavenger (hemoglobin, Hb) and NO inhibitors (N-nitro-l-arginine methyl ester, L-NAME), NaN3 (NR inhibitor) significantly increased the contents of MDA, H2O2, and O2-. The application of N solution enhanced the AsA-GSH cycle by increasing the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and ascorbate oxidase (AAO), compared with control (NH4+:NO3− = 0:100). Meanwhile, exogenous SNP significantly increased the above indicators. All these effects of N on AsA-GSH cycle were inhibited by the addition of Hb, L-NAME and NaN3 in N solution. The results also revealed that the N and SNP treatments upregulated the relative expression level of GR, MDHAR1, APXT, DHAR2, and AAO gene in mini Chinese cabbage leaves under low light stress. These results demonstrated that the appropriate NH4+:NO3− (10:90) induced NO synthesis which regulates the AsA-GSH cycle in mini Chinese cabbage seedlings under low light stress.

Prototype of Student Attendance Application Based on Face Recognition Using Eigenface Algorithm

Prototype of face recognition based attendance application that has been developed to overcome weaknesses in DTETI UGM student manual attendance system has several weaknesses. These weaknesses are a decrease in facial recognition accuracy when operating under conditions of varying environmental light intensity and in condition of face rotating towards z axis rotation centre. In addition, application prototype also does not yet have a database to store attendance results. In this paper, a new application prototype has been developed using Eigenface face detection and recognition algorithm and Haar-based Cascade Classifier. Meanwhile, to overcome prototype performance weaknesses of the previously developed application, a pre-processing method was proposed in another study was added. Processes in the method were geometry transformation, histogram levelling separately, image smoothing using bilateral filtering, and elliptical masking. The test results showed that in the category of various environmental light intensity conditions, face recognition accuracy from developed application prototypes was 16.71% better than previous application prototypes. Meanwhile, in category of face slope conditions at z axis rotation centre, face recognition accuracy from developed application prototype was 38.47% better. Attendance database system was also successfully implemented and running without error.

Light Intensity Modulates the Efficiency of Virus Seed Transmission through Modifications of Plant Tolerance.

Increased light intensity has been predicted as a major consequence of climate change. Light intensity is a critical resource involved in many plant processes, including the interaction with viruses. A central question to plant–virus interactions is understanding the determinants of virus dispersal among plants. However, very little is known on the effect of environmental factors on virus transmission, particularly through seeds. The fitness of seed-transmitted viruses is highly dependent on host reproductive potential, and requires higher virus multiplication in reproductive organs. Thus, environmental conditions that favor reduced virus virulence without controlling its level of within-plant multiplication (i.e., tolerance) may enhance seed transmission. We tested the hypothesis that light intensity conditions that enhance plant tolerance promote virus seed transmission. To do so, we challenged 18 Arabidopsis thaliana accessions with Turnip mosaic virus (TuMV) and Cucumber mosaic virus (CMV) under high and low light intensity. Results indicated that higher light intensity increased TuMV multiplication and/or plant tolerance, which was associated with more efficient seed transmission. Conversely, higher light intensity reduced plant tolerance and CMV multiplication, and had no effect on seed transmission. This work provides novel insights on how environmental factors modulate plant virus transmission and contributes to understand the underlying processes.

Effect of environmental factors on the biomass and lipid production of microalgae grown in wastewaters

The cultivation of a microalgae-bacteria consortium in a ternary blend of wastewaters was carried out by varying three variables (organic carbon content in the form of glycerol, CO2 addition, and light intensity) using a 23 full factorial design. An analysis of variance was performed to assess the effects of each factor and their interactions on the responses of biomass productivity, lipid content, and nutrients uptake. Also, a principal component analysis (PCA) was conducted to study correlations among the variables. Light intensity and its interaction with organic carbon were the main factors affecting cells growth. The biomass productivity (maximum value of 105.2 mg⋅L−1⋅d−1) was negatively affected by organic carbon and CO2 addition and positively affected by light intensity. Higher lipid contents (maximum value of 17.2%) were found at conditions of low light intensity and high organic carbon in the cultures. Lipid production was related to ammonia-N uptake by the cells. The addition of organic carbon aided the uptake of nitrates-N, ammonia-N, and total organic carbon, and the light intensity reduced these values (maximum values of 100%, 90% and 86%, respectively). The PCA corroborated the relations found between the factors and responses in the factorial analysis and revealed correlations among the responses measured. The main source of nitrogen at conditions of high light intensities was nitrates, while ammonia was the preferred nitrogen source when the cultures were grown under high organic carbon contents as it was indicated by the values of nutrients uptake.

SMALL RADISH FOR LIGHT CULTURE: CHALLENGES AND PROSPECTS

Intense light culture, the most impotent part of a regulated agroecosystem, makes it possible to produce high quality plant products all year round in any region of the world in close proximity to the consumer. It is most economically viable to use light culture for growing vegetables in the Far North, where there is an acute shortage of fresh vegetables and vitamins. Our studies of the range of different vegetable crops have shown that when using artificial lighting and low-volume cultivation technologies, many plant species and varieties have low productivity, low adaptability to the relevant conditions, and therefore unprofitable for mass production. To expand the range of vegetable products intended for cultivation in the light culture, it is necessary to do a massive screening of the varieties and hybrids of various crops available in the world assortment with the aim of selecting the best and also purposeful breeding of new forms and varieties maximally adapted to the appropriate cultivation technologies. The purpose of this work was to create new forms of small radish for light culture, having the necessary complex of economically valuable characters. The use of the previously developed methodology of predicting transgressions for economically valuable plant traits allowed us to obtain new promising forms of radish with using purposeful hybridization and subsequent stabilizing selection. Their characteristics are high productivity and early maturity (ripeness to harvesting for 21-25 days from seeding), the ability to produce marketable yield of roots in a small volume of root medium, resistance to bolting at higher temperatures. A number of the obtained forms also has a compact rosette of leaves and an almost glabrous leaf of the salad type. Marketable productivity of new forms of radish in intense light culture conditions reaches 5,5 kg/m2 (for hybrids F1) and 4 kg/m2 for stable lines, which is twice or more than the productivity of the parental cultivars and one and a half times more than the best in productivity cultivars that were tasted in light culture.

Lutein and zeaxanthin isomers may attenuate photo-oxidative retinal damage via modulation of G protein-coupled receptors and growth factors in rats

BackgroundRetina photoreceptor cells are specially adapted for functioning over comprehensive ambient light conditions. Lutein and Zeaxanthin isomers (L/Zi) can protect photoreceptor cells against excessive light degeneration. Efficacy of L/Zi has been assessed on some G protein-coupled receptors (GPCRs), transcription and neurotrophic factors in the retina of rats exposed to incremental intense light emitting diode (LED) illumination conditions. MethodsForty-two male rats (age: 8 weeks) were randomly assigned to six treatment groups, 7 rats each. The rats with a 3x2 factorial design were kept under 3 intense light conditions (12hL/12hD, 16hL/8hD, 24hL/0hD) and received two levels of L/Zi (0 or 100 mg/kg BW) for two months. Increased nuclear factor-kappa B (NF-κB), glial fibrillary acid protein (GFAP), and decreased Rhodopsin (Rho), Rod arrestin (Sag), G Protein Subunit Alpha Transducin1 (Gnat1), neural cell adhesion molecule (NCAM), growth-associated protein-43 (GAP43), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and heme oxygenase 1 (HO-1) were observed in 24 h light intensity adaptation followed by 16 h IL and 8 h D. ResultsL/Zi administration significantly improved antioxidant capacity and retinal Rho, Rod-arrestin (Sag), Gnat1, NCAM, GAP43, BDNF, NGF, IGF1, Nrf2, and HO-1 levels. However, the levels of NF-κB and GFAP levels were decreased by administration of L/Zi. ConclusionsAccording to these results, L/Zi may be assumed as an adjunct therapy to prevent early photoreceptor cell degeneration and neutralize free radicals derived from oxidative stress.

Preparation and characterization of water-based concentrated carbon nanotubes slurry with high dispersibility and stability

Abstract In order to apply the excellent properties of carbon nanotubes to the field of biomedicine, water-based high concentration carbon nanotubes(CNTs) slurry with high dispersibility and stability was prepared by adjusting illumination conditions and pH values. The infrared spectroscopy, zeta potential, TEM and digital camera were used to investigate the effect of illumination conditions and pH values on the dispersibility and stability of the CNTs slurry. The results show that the CNTs slurry has more functional groups and can be sufficiently oxidized in the absence of light than in the natural and intense light conditions. And the higher light intensity used for oxidation treatment caused a decrease of the functional groups and the surface activity of the CNTs in the slurry. The increase of the pH value can promote electrostatic repulsion, and the enhancement of light intensity can decrease the electrostatic repulsion. So, the CNTs individuals oxidized in the absence of light possessed high dispersibility and stability as varying pH value from 11.5 to 4, which slurry concentration is 10 wt% and no CNTs settlement was observed for nearly one year. However, the CNTs in the water-based carbon nanotube slurry prepared under other illumination conditions re-agglomerated and settled after several days, especially when the pH value is below 4.

Enhancing growth and lipid productivity in Dunaliella salina under high light intensity and nitrogen limited conditions

Microalgae are potential feedstocks for renewable energy production and solving some environmental problems. The effects of nitrogen, sulfur and phosphorus limitations, light intensity (100 or 800 μmol·m−2·s−1) and CO2 concentration (1% or 10%) on growth and lipid accumulation were investigated for Dunaliella salina. The effects of nutrient limitation and light intensity were also characterized by flow cytometry and photosynthetic activity. High light intensity promoted the carbohydrate accumulation and low light intensity was beneficial to lipid accumulation under N-limited conditions. The highest biomass productivity was 1.03 g L−1 d−1 at day 2 under 1% CO2, high light intensity and 1/4 N conditions. The highest lipid productivity was 0.24 g L−1 d−1 at day 2 under 10% CO2, high light intensity and N-limited conditions. A novel approach was proposed and it is helpful for the microalgae biofuel development in future.

Enhanced phycocyanin and protein content of Arthrospira by applying neutral density and red light shading filters: a small‐scale pilot experiment

AbstractBACKGROUNDThe cyanobacterium Arthrospira contains proteins and the blue pigment phycocyanin that can be used as a natural colourant in the food industry. The aim of this study was to investigate a strategy for increasing the yield of phycocyanin and protein from Arthrospira cultures by shading the cultures with neutral density and red light filters. Experiments were conducted under three different irradiance conditions: (i) laboratory tests under relatively low light intensities (100 μmol m−2 s−1), (ii) laboratory tests under relatively high light intensities (516 μmol m−2 s−1) and (iii) scaled‐up tests under natural conditions by cultivating Arthrospira in raceway ponds in a greenhouse.RESULTSIn all cases, shading of cultures with red filters resulted in biomass with increased phycocyanin content achieving a maximum of 134, 71 and 121 mg g−1 under low light intensity, high light intensity and natural conditions, respectively. Under high light intensity and natural conditions, shaded cultures displayed phycocyanin of higher purity and increased protein content, which reached up to 43 and 65%, respectively.CONCLUSIONSShading of Arthrospira cultures by low‐cost polyester red light filters may be an effective way for enhancing phycocyanin production and improving its purity in outdoor ‘spirulina farms’. © 2019 Society of Chemical Industry

Serotonin 5-HT1A Receptor Biased Agonists Display Differential Anxiolytic Activity in a Rat Social Interaction Model.

When placed in an unfamiliar and brightly lit open-field, two adult male rats that have not previously interacted display a low level of social interaction (SI) attributed to an anxiety-like state. The SI test has therefore been used to explore anxiolytic/antistress activity. Here, we investigated the effects of serotonin 5-HT1A receptor agonists displaying various activity profiles, i.e. partial vs full agonist efficacy and pre- versus postsynaptic 5-HT1A receptor preferential activation by "biased agonists". Adult male Sprague-Dawley rats were housed singly before starting the social interaction session. At 30 min before being placed in an open-field, both rats of the dyad were injected (i.p or s.c.) with either vehicle, diazepam (as a reference compound), or one of six 5-HT1A receptor agonists: NLX-101 (a.k.a. F15599), F13714, S15535, flesinoxan, 8-OH-DPAT, and buspirone. Time spent in SI (following, sniffing, playing) was recorded for 10 min. Time spent in SI was inversely correlated with light intensity, with values dropping nearly by half (212.6 ± 18.8 vs 113.7 ± 7.0 s) between 10 and 300 lx (measured at floor level). Under the high light intensity conditions (300 lx), diazepam showed a bell-shaped curve, significantly increasing SI (78% increase in interaction time above control) at 1 mg/kg i.p. only. In the case of 5-HT1A receptor ligands, full agonists, whether nonpreferential (flesinoxan, (±)8-OH-DPAT) or preferential for presynaptic receptors (F13714), showed the strongest activity in this model. The preferential presynaptic receptor partial agonist, S15535, was also active over a wide dose-range, although with lower efficacy than F13714. In contrast, NLX-101, a high-efficacy biased agonist that preferentially activates postsynaptic 5-HT1A receptors, exhibited little activity. The clinical anxiolytic, buspirone, showed a marked effect likely due to its partial agonist activity at 5-HT1A presynaptic receptors. These data support the hypothesis that enhancement of SI in this model is mediated by preferential agonist activation of presynaptic 5-HT1A receptors, and confirm previous studies using local microinjections of (±)8-OH-DPAT. They further support the utility of noninvasive administration of biased agonists for exploring the activity of 5-HT1A receptor subpopulations.

Influence of light intensity on cadmium uptake and toxicity in the cyanobacteria Synechocystis sp. PCC6803

The mechanisms of cadmium toxicity to cyanobacterial photosynthesis have been extensively studied, but the response mechanisms to combinations of different cadmium concentrations and different light intensities are not yet well understood. The two principal objectives of the present work were to: 1) study the short term (5 h) toxic effects of cadmium on Synechocystis PCC6803 under three different culturing light intensity conditions; and, 2) investigate the effects of light history on Cd toxicity to Synechocystis. The maximal (ФM) and operational (Ф’M) photosystem II quantum yields, photosystem I quantum yield [Y (I)], cyclic electron flow, relative photochemical quenching (qPrel), relative non-photochemical quenching (qNrel), relative unquenched fluorescence (UQFrel), pigment contents, and cadmium uptake were evaluated when Synechocystis cells were treated with cadmium for 5 h under three different light conditions. We demonstrated that cadmium toxicity was enhanced with increasing growth light intensities due to increased cadmium uptake under higher light exposures, and the photoprotective mechanisms could not cope with cadmium and light stress under high light conditions. We also investigated Cd toxicity to Synechocystis adapted to three growth light intensities and subsequently shifted to different light intensity conditions to compare the effects of light regime shift on cadmium toxicity. We observed increased cadmium toxicity when the cells were transferred from low light to high light conditions. Interestingly, Synechocystis cells grown at high light intensities were more tolerant to cadmium than cells grown at low light intensities after the same light regime shift, due to the development of photoprotective mechanisms.

Arched Bamboo Charcoal as Interfacial Solar Steam Generation Integrative Device with Enhanced Water Purification Capacity

AbstractInterfacial solar steam generation (ISSG) has received increasing attention in both industry and academia, and is considered a method with great potential for wastewater treatment and desalination. These practical applications require materials that fulfil several requirements: being low cost, being scalable in terms of processing, being environmentally friendly, and having a high, stable optical–thermal conversion efficiency of solar vaporization. Currently, biomass materials show very promising prospects for ISSG systems. Here, it is observed that bamboo charcoal (BC) possesses a series of unique advantages that make it a highly efficient ISSG device. The broadband light absorption and the arched and porous structural features of BC fulfil all the basic requirements of an ISSG device in localized heating, heat management, and water supply. The self‐contained arched BC device demonstrates high evaporation efficiency (84% under 1 sun radiation) and superb stability under strongly acidic, strongly alkaline, and intense light environment conditions. More importantly, the porous BC device can provide stable fresh water production that simultaneously promotes the purification of water via evaporation by heating. Finally, the low cost, environmentally sustainable, mechanically robust, and long‐term stable BC device is a potential opportunity for wastewater treatment and desalination in underdeveloped areas.

(3R, 3’R)-zeaxanthin protects the retina from photo-oxidative damage via modulating the inflammation and visual health molecular markers

Purpose: Zeaxanthin protects the macula from ocular damage due to light or radiation by scavenging harmful reactive oxygen species. In the present study, zeaxanthin product (OmniXan®; OMX), derived from paprika pods (Capsicum annum; Family-Solanaceae), was tested for its efficacy in the rat retina against photooxidation.Methods: Forty-two male 8-week-old Wistar rats exposed to 12L/12D, 16L/8D and 24L/0D hours of intense light conditions were orally administrated either 0 or 100 mg/kg BW of zeaxanthin concentration. Retinal morphology was analyzed by histopathology, and target gene expressions were detected with real-time polymerase chain reaction methods.Results: OMX treatment significantly increased the serum zeaxanthin concentration (p < 0.001) and ameliorated oxidative damage by increasing the antioxidant enzyme activities in the retina induced by light (p < 0.001). OMX administration significantly upregulated the expression of genes, including Rhodopsin (Rho), Rod arrestin (SAG), Gα Transducin 1 (GNAT-1), neural cell adhesion molecule (NCAM), growth-associated protein 43 (GAP43), nuclear factor-(erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase (HO-1) and decreased the expression of nuclear factor-κB (NF- κB) and GFAP by OMX treatment rats. The histologic findings confirmed the antioxidant and gene expression data.Conclusions: This study suggests that OMX is a potent substance that can be used to protect photoreceptor cell degeneration in the retina exposed to intense light.

Silicon based photodetector with Ru(II) complexes organic interlayer

In present work, the electrical properties and illumination effects were investigated for the silicon based photodetector with organic Ru(II) complexes interfacial layer. The current-voltage (I-V) and capacitance/conductance-voltage (C/G-V) measurements were analyzed to determine electrical and photoelectrical properties under dark and different solar light intensity conditions. The reverse bias current values under light conditions were higher than dark conditions, and this situation demonstrates that the fabricated device displays a photoconducting behavior. Besides, some crucial electrical parameters such as series resistance, barrier height and ideality factor values of prepared device were calculated by using current-voltage measurements. The ideality factor and barrier height values of fabricated device were calculated as 9.42 and 0.59 for dark condition. Besides to these experiments, transient photocurrent and photo-capacitance/conductance were also investigated under different light conditions. It was determined from transient measurements that the fabricated device has a high sensitivity to light. The photoresponse of the diode was determined to be around 4479 ± 1.9 under 100 mW/cm2 illumination. The examined C/G-V characteristics of the fabricated device strongly depend on voltage and frequency. The analyzed results suggest that the fabricated Al/Ru(II) complexes/p-Si/Al device can be used in rapidly developing optoelectronic applications, especially for the organic materials-based photodetector technology.

An Experimental Study of Photocatalytic Degradation of Congo Red Using Polymer Nanocomposite Films

Eco-friendly polymer nanocomposite films were synthesized using biodegradable polymers of chitosan and polyvinyl alcohol as polymeric matrices and carbon black nanoparticles as the reinforcement. These films were applied to study their applicability to industrial wastewater purification as a photocatalyst for degradation of Congo red as a target pollutant and to study the effect of the polymeric matrix types of the films on their performance as a semiconductor photocatalyst. Fourier-transform infrared (FT-IR) spectra and X-ray diffraction (XRD) were used to characterize the films. Visible light photocatalytic degradation of Congo red as a pollutant under various operational conditions of pH, dye concentration, contact time, and light intensity was performed. Photocatalytic results revealed that the polymeric substrate type does not play a major role in the photodegradation of the dye, and the best operational conditions were at a pH of 6 and a dye solution concentration of 8 mg/L.

Inter-Method Reliability of Pulse Volume Related Measures Derived Using Finger-Photoplethysmography

Abstract. Pulse volume (PV) and its related measures, such as modified normalized pulse volume (mNPV), direct-current component (DC), and pulse rate (PR), derived from the finger-photoplethysmogram (FPPG), are useful psychophysiological measures. Although considerable uncertainties exist in finger-photoplethysmography, little is known about the extent of the adverse effects on the measures. In this study, we therefore examined the inter-method reliability of each index across sensor positions and light intensities, which are major disturbance factors of FPPG. From the tips of the index fingers of 12 participants in a resting state, three simultaneous FPPGs having overlapping optical paths were recorded, with their light intensity being changed in three steps. The analysis revealed that the minimum values of three coefficients of Cronbach’s α for ln PV, ln mNPV, ln DC, and PR across positions were .948, .850, .922, and 1.000, respectively, and that those across intensities were .774, .985, .485, and .998, respectively. These findings suggest that ln mNPV and PR can be used for psychophysiological studies irrespective of minor differences in sensor attachment positions and light source intensity, whereas and ln DC can also be used for such studies but under the condition of light intensity being fixed.