Fluorescent Light Sources Research Articles

Optimization of photocatalytic fuel cells (PFCs) in the treatment of diluted palm oil mill effluent (POME)

Photocatalytic fuel cells (PFCs) are considered an advanced technology in wastewater treatment as they are able to remove organic based wastewater by using the principle of advanced oxidation processes (AOPs) and at the same time generate electricity. Despite PFCs being used to treat different types of organic based wastewater efficiently, the use of PFCs in palm oil mill effluent (POME) is still considered rare. Hence, the present research was carried out to determine the optimal conditions of contact time, pH, initial organic concentration and light intensity in order to remove the organic matter present in diluted POME. Our PFC system was constructed by using NaCl as the supporting electrolyte with ZnO/Zn as the photoanode and platinum wire as the cathode. The chemical oxygen demand (COD) removal efficiency and the amount of electricity generated was monitored in different optimization experiments using a conventional fluorescence light source. Under optimal conditions, the COD removal efficiency increased from 7% to 74 %, while the power density output also increased from 1.73 to 35.85 μW/cm2. The PFC was found to work optimally at pH 7 with a light intensity of 1300 lx for 6 h. Meanwhile, the scanning electron microscope (SEM) images revealed the high organic matter concentration in POME can lead to the deposition of an organic layer on the photoanode surface which subsequently reduced the COD removal efficiency to 17.4 %. This result has indicated that PFC is not suitable for treating the fresh POME directly from the mill, but it is more suitable for treating POME, from the last biological treatment pond.

Influence of resin content on the surface covered with adhesive

It is well known that the resin content within a particleboard influences the extent of the surface covered with adhesive and thus the properties of particleboards produced. The purpose of this research was to determine how the resin content and particle size class influence the surface of particle covered with the adhesive. For that purpose, wood particles used for particleboard production were used. Particles were blended with a UF adhesive with 0.05% of fluorescent dye added prior to blending and subsequently exposed to a resin curing temperature of 180 °C. The resin content was varied between 7.5 and 12.5%. The adhesive surface coverage was determined using a microscope with a fluorescent light source and a CCD camera. The results showed that the surface coverage increased with increasing resin content and increasing wood particle size.

Analysis of the distribution of microfractures and micropores within granitic rock using simultaneous polarization–fluorescence microscopy

The analysis of the distribution of microfractures and micropores is important to accurately characterise mass transfer within a rock body. In this paper, a new ‘simultaneous polarization–fluorescence microscopy’ method is presented, which can be used to analyse the distribution of microscopic voids, including microfractures and micropores, in granitic rock. In this method, thin sections prepared with fluorescent dye are analysed under a polarizing microscope equipped with a fluorescent reflected light source. Using both the transmitted and the fluorescent light sources, both the distribution of microfractures and micropores, and petrographic characteristics (mineral occurrences) can be determined efficiently and simultaneously. The distribution of microfractures and micropores observed in images of granites obtained using simultaneous polarization–fluorescence microscopy is consistent with the distribution observed in backscattered electron images. The low magnification characterisation of the distribution of microscopic voids also provides targeting for subsequent studies including scanning electron microscopy under high magnification, chemical analysis, and image processing.

Photostabilization of rubberwood using cerium oxide nanoparticles. Part 1: Characterization and colour changes

Light induced darkening and deterioration of wood used outdoors is undesirable. Photoprotection of wood could be achieved by using additives that reflect or absorb harmful radiation responsible for degradation. Nano metal oxides have strong absorption in the UV range of solar radiation and good transparency in the visible region. They offer unique benefits in protecting coatings and coated substrates from being degraded by UV radiation. However, to exploit the properties of nanoparticles, homogenous dispersion without agglomeration is necessary. In the present work, the photostabilization of rubberwood surfaces coated with cerium oxide (CeO2) was studied. The nanoparticles were surface functionalized with an organic alkoxy silane (3-glycidyloxypropyltrimethoxy silane) to improve the homogenous distribution in coatings, and the modified nanoparticles were dispersed in isopropanol and polyurethane (PU) coating. Rubberwood surfaces coated with dispersed nanoparticles (concentration 0.5 % to 6 % w/v) were exposed to a fluorescent UVA light source (λ=340 nm) at 60 °C in an accelerated weathering tester for 500 h and 1000 h. Colour changes due to UV light exposure were monitored using a spectrocolourimeter. Dispersion of CeO2 nanoparticles in PU coatings (concentration >2 %) restricted the photoyellowing of wood polymers.

Development of a fluorescence imaging method to measure void fractions of gas–liquid two-phase flows in a small tube-window for transparent fluids

Void fraction is one of the most important parameters to characterize gas–liquid two-phase flow. Yet it has been puzzling people for a long time how to measure it effectively and accurately. In this paper, we develop a fluorescence imaging method that combines the techniques of fluorescence imaging with image processing to measure the two-phase flow cross-sectional void fraction in a horizontal tube window. At first, a tube window is designed and constructed. By illuminating the fluid containing fluorescent dyes inside the tube window with a sheet laser, fluorescence is produced and emits only from the illuminated liquid phase to create a fluorescent light source in the tube cross section. Then, the sequential cross-sectional images of the fluorescent light sources are recorded with a high speed camera equipped with a narrow band filter. Further, the captured images are processed to identify the gas–liquid interface, and to extract the liquid area from the image by segmentation. The cross-sectional void fraction can thus be obtained by comparing the gas area to the total cross-sectional area. Finally, the bulk void fraction can then be indirectly measured by averaging all the cross-sectional void fraction in a given time. Both simulation and experiment were performed to verify and evaluate this method. The simulated cross-sectional images were in good agreement in shape with those observed correspondingly for various flow patterns including slug flow, bubble flow, annular flow and stratified flow. The measured bulk void fractions were in good agreement with those predicted by the slip ratio model and the model within the range of error, 22% and 14%, respectively, even without a careful calibration of image deformation.

Colorimetric Observer Categories for Young and Aged Using Paired-Comparison Experiments

Observers with normal color vision have different color perceptions since their retinal cones have different spectral responses, especially when the color pairs are constituted by different primary colors. In order to categorize the color-matching functions (CMFs) for young and aged observers, seven devices with different primary colors were performed on the clustering of observers’ CMFs. Four CMFs were generated from Beijing Institute of Graphic Communication (BIGC) with paired-comparison color matching experiments based on five printed colors from young and aged observers performed under fluorescent light source (Experiment I). Besides, color comparison experiments based on three printed colors under light emitting diodes (LEDs) light source were also carried out (Experiment II). And then, the existing CMFs, including Commission Internationale de l’ Eclairage 1964 (CIE 1964), CIE 1989 standard deviate observer (CIE 1989 SDO), CIE 2006, Sarkar 1 to Sarkar 8, Asano 1 to Asano 10, BIGC 1 to BIGC 4 were tested with the results from Experiments I and II respectively. The results indicated that the visual data from young and aged observers had quite large discrepancies. When they viewed printed materials illuminated by fluorescent and LED light sources in a field of view larger than 10°, based on the standardized residual sum of squares (STRESS) values and the number of the observers contributed to the minimum STRESS values, two new CMFs were proposed to represent the young and aged observers who participated in our experiments.

Visible-light mediated facile dithiane deprotection under metal free conditions

Visible light mediated facile and selective dithiane deprotection under metal free conditions is developed. Eosin Y (1 mol%) proved to be an effective catalyst for the dithiane deprotection under the ambient photoredox conditions. The standard household compact fluorescent light source (CFL bulb) proved to be effective under open-air conditions in aqueous acetonitrile at room temperature. The protocol that exhibits a broad substrate scope and functional group tolerance has been shown to expand to a range of transformations for the electron-rich and -deficient thioacetals and thioketals. The synthetic utility of this protocol has also been demonstrated by gram-scale application.

Fluorescent incandescent light sources from individual quadrilateral ZnO microwire via Ga-incorporation.

By means of nanophotonics principle, the thermal radiation can be tailored, thus, traditional tungsten lamp light source can glow the vitality and the vigor due to the low-efficiency approaching to commercial fluorescent or light-emitting diode bulbs. However, too far by demanding exacting terms, such as high-temperature thermal radiation (∼ 3000 K), high-vacuum encapsulation technology, restricted spectrally controllable source and so on, tungsten-based incandescent lamp filament has greatly limited the application in lighting, diagnosis and treatment, communication, imaging, etc. Herein, individual Ga-doped ZnO microwires (ZnO:Ga MWs) were successfully synthesized, which can be utilized to construct typical incandescent sources. By adjusting the Ga-incorporation, lighting colors are tuned in the visible spectral band. Especially, by incorporating Au quasiparticle nanofilms, the incandescent lighting features can further be modulated, such as the emission peaks, the modulation of lighting regions. Therefore, individual ZnO:Ga MWs based incandescent emitters can undertake a new function of the oldest, affordable and easily prepared light sources. While preliminary, individual ZnO:Ga MWs being treated as efficient incandescent light sources, can also open up intriguing scientific questions, and possible applications of linear, transparent, flexible displays and optical interconnects with electronic circuits.

Impact of light-emitting diode and compact fluorescent light source type and cage tier on layers reared in an enriched cage system Part 1: Production performance and egg quality

This study?s aim was to investigate the effects of age, light source type (light-emitting diode (LED), and compact fluorescent (FLO)), and cage tier on production performance and egg quality traits of layers reared in the enriched cage system. A total of 800 Nick Chick White layers were used in the study. A total of 800 eggs were used for egg quality traits at 25 and 45 weeks of age. The enriched cage tiers were coded as I, II, III, and IV from bottom to top. Layer age significantly affected egg mass, hen-day egg production rate, hen-house egg production rate, feed consumption, feed conversion ratio, damaged egg ratio (P < 0.05), egg weight, shape index, shell thickness, albumen weight, yolk weight, shell weight, yolk color index, albumen ratio, yolk ratio, and shell ratio (P < 0.001). The higher egg mass, egg weight, albumen weight, yolk weight, shell thickness (P < 0.001), dirty egg ratio (P < 0.01), and lower FCR, yolk color index (P < 0.01), shell ratio (P < 0.01) were found in the FLO group when compared to the LED group (P < 0.05). Highest body weight was found in cage tier I at 45 weeks of age (P < 0.001). Level of cage tier significantly affected 50% egg production age, egg mass, hen-day egg production rate, hen-house egg production rate, and dirty egg ratio (P < 0.01). Level of cage tier significantly affected 5% egg production age, FCR, and shape index (P < 0.05). It can be concluded that the hens in the FLO group were better than the LED group in terms of some production and egg quality traits.

Color effect of light sources on peridot based on CIE1976 L*a*b* color system and round RGB diagram system

AbstractPrevious research indicated that the peridot's color is dominated by the selective absorption of visible light caused by ferrous ion, the hue angle of which is in an inverse ratio of the concentration of Fe2+. This article focuses on the color effect of peridot under different standard light sources based on the CIE1976 L*a*b* color space system and round RGB diagram system and tries to find the best one for its grading and display. Based on the results of a series of experiments, including electron microprobe analysis, spectrophotometer, UV‐Vis spectrum, standard illumination box, and Munsell neutral color chips, it was suggested that the spectral power distribution and color temperature of a standard light source significantly influence the color of peridot in terms of lightness and chroma, particularly in the hue of peridot. As for color grading and displaying of peridot, standard light source A fails to fit in, and the color of peridot under a fluorescent light source has a higher chroma but a lower hue angle than that under daylight light source. The best choice for grading and displaying peridot is the standard light source D65. It is better to distinguish the hue of peridot when it is calculated by the round RGB diagram system.

Aging Condition and Retail Display Lighting Impact Retail Display Life and Lipid Oxidation of Beef Biceps Femoris Steaks

The objective of this study was to determine the impact of aging method and retail display lighting type on the discoloration and oxidation of a beef muscle with low color stability. Beef biceps femoris (BF; n = 38) were fabricated 48 h postmortem and aged for 16 d post fabrication in either wet (vacuum packaged) or dry conditions. After aging steaks (n = 9) were cut from each BF and randomly assigned to 1 of 3 retail display lengths: 1, 3, or 5 d and 3 light treatments: light emitting diode (LED), high-UV fluorescent (HFLO), or low-UV fluorescent (FLO). Steaks were removed from retail display, and were subjected to instrumental color analysis (L*, a*, b*), surface myoglobin redox forms, lipid oxidation, and metmyoglobin reducing activity. Dry aging resulted in greater (P &lt; 0.05) redness, as determined by a*, saturation index, and hue angle values of beef BF steaks, compared to wet aging. Significant interactions (P &lt; 0.05) between aging method and retail display day were reported for a/b ratios, hue angle, deoxymyoglobin concentrations, and lipid oxidation values. Dry aging resulted in increased (P &lt; 0.05) lipid oxidation over the duration of retail display, as determined by thiobarbituric acid reactive substances (TBARS), in comparison to wet aging. Light by day interactions (P &lt; 0.05) occurred for b*, metmyoglobin concentrations, oxymyoglobin concentrations, and saturation index values. Data indicate that utilization of fluorescent light sources promoted greater redness retention in a muscle with low color and oxidative stabilities over the duration of retail display in comparison to LED light sources.

Responses of Favorita Potato Plantlets Cultured in Vitro under Fluorescent and Light-Emitting Diode (LED) Light Sources

The effects of different light-emitting diodes on the growth, morphogenesis, and tuberization of ‘Favorita’ potato (Solanum tuberosum L.) plantlets were determined. Shoot cuttings were cultured in vitro for 21 days under six different light types: fluorescent lamp, 100% red LED, 100% blue LED, and three blue and red LED combinations (80R/20B, 70R/30B, 50R/50B). Plant height was the greatest under 100R LED, whereas root length and fresh weight were the greatest under 80R/20B LED. Chlorophyll content and total soluble carbohydrate content were greatest when R LED was combined with at least 30% B LED. Carotenoid content and average weight of tubers were the greatest when both R and B LED were present. The diameter of the biggest tuber was the greatest under 70R/30B LED. Under 100% R, single tubers had the least average weight, while other treatments showed no significant difference. In conclusion, 70R/30B LED is best for growing Favorita potato plantlets in vitro.

Modeling the effects of light sources on the growth of algae

Algae are fast growing microorganisms and beneficial in many ways, especially concerning food supplement, alternative energy, and wastewater treatment. Naturally, they need a light:dark regime for productive photosynthesis. To have more insight into how light affects their growth, we investigate the effect of light sources (fluorescent and LED) on algae growth both experimentally and computationally via modeling. It was found that growth in the fluorescent light source is relatively better than in other sources. Computational data analyses and detailed discussions are presented. Lastly, a more generalized growth model of microalgae for incorporation of other factors and variables is necessary for more realistic modeling of real-world systems.

LED Grow Lights Alter Sorghum Growth and Sugarcane Aphid (Hemiptera: Aphididae) Plant Interactions in a Controlled Environment

Normal growth and production of plant tissues requires water, carbon dioxide, nutrients, and light. Light-emitting diodes (LED) are being used increasingly as a substitute for fluorescent or incandescent light sources in greenhouse horticulture because of their small size, durability, wavelength specificity, long operating life, and efficiency in offering photosynthetically active radiation at lowered energy costs compared to conventional lights. However, studies conducted to test the effects of these lights reveal that spectral properties of light-emitting diodes can have dramatic effects on plant morphology, nutrient uptake, and pathogen development when plants are grown under the incorrect light spectrums. We grew sorghum plants under a light-emitting diode grow panel, and compared it to plants grown under conventional fluorescent lighting within identical environmental chambers. Light-emitting diode lighting resulted in deleterious sorghum growth with fewer true leaves formed, reduced plant height, lower chlorophyll content, and an unusual pink to purple coloration of the plant tissue when compared to sorghum grown under conventional lighting. All 4 of the different sorghums grown under light-emitting diodes had 2× the amount of biomass measured as dry weights for upper (stems and leaves) and lower (root mass) when compared to the conventional lighting. When sorghums were infested with sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), both light sources supported a similar number of aphids but plants grown under light-emitting diodes had higher damage ratings than those under conventional lights for both known resistant and susceptible sorghums. For future trials, sorghum should not be grown using the light-emitting diode lights when assessing host-plant resistance to aphid infestation.

Room-temperature synthesis of Bi/BiOBr composites for the catalytic degradation of ciprofloxacin using indoor fluorescent light illumination

This paper reports an efficient process for the room-temperature production of Bi/BiOBr composites. For this purpose, BiOBr was prepared via a solid state synthesis, while metallic bismuth nanoparticles were loaded onto the surface of BiOBr via a chemical reduction process in NaBH4 aqueous solution. Subsequently, both pristine BiOBr and Bi/BiOBr composites were characterized, and their photocatalytic efficiency was evaluated by degrading aqueous ciprofloxacin (CIP) solution (100 mL, 20 ppm), placed at approximately 2.5 m away from a 25 W indoor fluorescent light source. During the photocatalytic degradation process, Bi/BiOBr-20 showed a superior performance as its degradation efficiency reached 94.8% within 60 min, while 85.8% of the total organic carbon (TOC) has been removed after 120 min. Such enhanced performance has been attributed to the efficient separation of the photogenerated charge carriers and strong light absorption by Bi/BiOBr-20 composite photocatalyst. Results from active species studies were used in proposing a possible mechanism for the photodegradation process. The reusability study revealed negligible loss in the performance of Bi/BiOBr-20 composite photocatalyst over the five cycles investigated. Such facile room-temperature production process presented herein, could be useful in the design and large scale production of other bismuth-based photocatalysts.

Interchromophoric Interactions Determine the Maximum Brightness Density in DNA Origami Structures.

An ideal point light source is as small and as bright as possible. For fluorescent point light sources, homogeneity of the light sources is important as well as that the fluorescent units inside the light source maintain their photophysical properties, which is compromised by dye aggregation. Here we propose DNA origami as a rigid scaffold to arrange dye molecules in a dense pixel array with high control of stoichiometry and dye-dye interactions. In order to find the highest labeling density in a DNA origami structure without influencing dye photophysics, we alter the distance of two ATTO647N dyes in single base pair steps and probe the dye-dye interactions on the single-molecule level. For small distances strong quenching in terms of intensity and fluorescence lifetime is observed. With increasing distance, we observe reduced quenching and molecular dynamics. However, energy transfer processes in the weak coupling regime still have a significant impact and can lead to quenching by singlet-dark-state-annihilation. Our study fills a gap of studying the interactions of dyes relevant for superresolution microscopy with dense labeling and for single-molecule biophysics. Incorporating these findings in a 3D DNA origami object will pave the way to bright and homogeneous DNA origami nanobeads.

Gd3Li3Te2O12:U6+,Eu3+: A Tunable Red Emitting Garnet Showing Efficient U6+ to Eu3+ Energy Transfer at Room Temperature

Since the invention of fluorescent light sources, there is strong interest in Eu3+ activated phosphors as they are able to provide a high color rendering index (CRI) and luminous efficacy, which will also hold for phosphor converted light emitting diodes. Due to an efficient U6+ to Eu3+ energy transfer in Gd3Li3Te2O12:U6+,Eu3+, this inorganic composition shows red photoluminescence peaking at 611 nm. That means Eu3+ photoluminescence can be nicely sensitized via excitation into the U6+ excitation bands. Therefore, photoluminescence properties, such as temperature dependent emission and emission lifetime measurements, are presented. Charge transfer bands were investigated in detail. Additionally, density functional theory calculations reveal the band structure of the pure, i.e., non-doped host material. Obtained theoretical results were evaluated experimentally by the aid of diffuse UV reflectance spectroscopy.

Indoor-type photovoltaics with organic solar cells through optimal design

Indoor solar cells are an attractive option to install in buildings to harvest the energy emitted by indoor lighting. They can be implemented as a stand-alone grid, or as part of an integrated energy harvesting unit. Previous research has utilized amorphous silicon and dye-sensitized solar cells for power generation from a fluorescent light source. In our study, we evaluated the applicability of a poly (3-hexylthiophene):indene-C60 bisadduct solar cell to harvest the light spectrum from an indoor light-emitting diode (LED). Because the absorption peak of poly (3-hexylthiophene) overlaps the LED spectrum peak, it serves as a good candidate for indoor light harvesting under an LED source. We have extracted the power conversion efficiency of the solar cell under different LED illuminance values, such as 200, 800, 1000, and 2000 lx. With the help of finite-difference time domain simulations, we optimized the solar device structure for each illuminance. The results detailed in this article were intended to assess the applicability of organic solar cells as indoor photovoltaics, and to provide a methodology to optimize the photovoltaic structure to maximize its efficiency.

Photocatalytic performance of highly transparent and mesoporous molybdenum-doped titania films fabricated by templating cellulose nanocrystals

In this paper, the synthesis of mesoporous Mo-doped titania films templated by cellulose nanocrystals (CNCs) and their photocatalytic performance are reported for the first time. The prepared titania composite precursors containing the CNCs and molybdenum chloride were spin-coated on indium tin oxide (ITO) glass substrate, followed by calcining at 400 °C for 1 h. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM), and UV–vis spectrometer were employed to characterize the phase composition, pore structure, morphology, and optical property of the titania films in relation to CNCs templating and Mo doping. Photocatalytic performances of the titania films were also evaluated on the photodegradation of trichloroethylene under a fluorescent light source. The Mo-doped titania films with CNCs templating were highly transparent and mesoporous, exhibiting only anatase phase, high specific surface areas ranging in 135.4 – 149.0 m2/g, and small crystallite sizes of 9.5 – 11.1 nm. The results indicate that Mo ions were successfully doped by substituting for Ti ions in the titania lattice. The Mo doping stabilized the anatase phase and also increased the surface area of the CNCs-templated titania film while decreasing the mean pore width. Notably, the visible light absorption capacity and photocatalytic activity of the CNCs-templated titania films doped with Mo were dramatically greater than those of the pure and the CNCs-templated titania films, which is ascribed to the decreased recombination rate of photoexcited charges and the increased surface area with aids of the CNCs templating and the Mo doping.

Colour differences in Caucasian and Oriental women's faces illuminated by white light-emitting diode sources.

To provide an approach to facial contrast, analysing CIELAB colour differences (ΔEab,10∗) and its components in women's faces from two different ethnic groups, illuminated by modern white light-emitting diodes (LEDs) or traditional illuminants recommended by the International Commission on Illumination (CIE). We performed spectrophotometric measurements of spectral reflectance factors on forehead and cheek of 87 young healthy women (50 Caucasians and 37 Orientals), plus five commercial red lipsticks. We considered a set of 10 white LED illuminants, representative of technologies currently available on the market, plus eight main illuminants currently recommended by the CIE, representative of conventional incandescent, daylight and fluorescent light sources. Under each of these 18 illuminants, we analysed the magnitude and components of ΔEab,10∗ between Caucasian and Oriental women (considering cheek and forehead), as well as for cheek-forehead and cheek-lipsticks in Caucasian and Oriental women. Colour-inconstancy indices for cheek, forehead and lipsticks were computed, assuming D65 and A as reference illuminants. ΔEab,10∗ between forehead and cheek were quantitatively and qualitatively different in Orientals and Caucasians, but discrepancies with respect to average values for 18 illuminants were small (1.5% and 5.0% for Orientals and Caucasians, respectively). ΔEab,10∗ between Caucasians and Orientals were also quantitatively and qualitatively different both for forehead and cheek, and discrepancies with respect to average values were again small (1.0% and 3.9% for forehead and cheek, respectively). ΔEab,10∗ between lipsticks and cheek were at least two times higher than those between forehead and cheek. Regarding ΔEab,10∗ between lipsticks and cheeks, discrepancies with respect to average values were in the range 1.5-12.3%, although higher values of up to 54.2% were found for a white RGB LED. This white RGB LED provided the highest average colour-inconstancy indices: 17.1 and 11.5 CIELAB units, under reference illuminants D65 and A, respectively. Colour contrasts in women's faces under CIE standard illuminants for outdoor and indoor conditions may be strongly altered using specific white LEDs. More research needs to be performed on the impact of spectral power distribution of light sources with high colour rendering indices on visual colour appearance of cosmetic products.