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[IEEE 2018 IEEE 7th International Conference on Photonics (ICP) - Langkawi, Malaysia (2018.4.9-2018.4.11)] 2018 IEEE 7th International Conference on Photonics (ICP) - Etched Fiber Bragg Grating Sensor for Nitrate Sensing Application
摘要： We demonstrate a reliable method to detect the concentration of Nitrate in water using an etched Fiber Bragg Grating (FBG) sensor. The sensor was etched using 48% Hydrofluoric (HF) acid solution to function as a chemical sensor and interact with Nitrates. The Bragg wavelength ((cid:2)b) shifted due to the changes of Nitrate concentration. The sensitivity achieved by this sensor is 2.4 x 10-3 nm/ppm. The overall shift of the Bragg wavelength is 0.12 nm from 0 – 50 ppm.
关键词： Nitrate ions,Fiber Bragg Grating sensor
更新于2025-09-23 15:21:01
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Intimately coupled TiO2/g-C3N4 photocatalysts and in-situ cultivated biofilms enhanced nitrate reduction in water
摘要： Nitrogen pollution has become a major threat to the aquatic environment, and the key to solve this problem is to enhance the nitrate reduction in water. Intimately coupled photocatalysis and biodegradation (ICPB) is a novel technique for degradation of bio-recalcitrant pollutants; however, it has not been used for nitrate reduction. This study applied a system that intimately coupled TiO2/g-C3N4 photocatalysts and in-situ cultivated biofilms for nitrate reduction in water without additional electron donors. The result shows a nitrate removal rate up to 40.3% in ICPB after 16 h. Furthermore, the N2 selectivity was 86.3%, which was higher than that for other protocols. In ICPB, nitrate was first reduced to nitrite, which was mainly contributed to the effect of biofilms. Then, nitrite was reduced via the cooperation of photocatalysts and biofilms, which benefited both low production of undesirable products and high selectivity of N2. Moreover, the growth of the microbes during the ICPB were favorable for denitrification. In conclusion, light-induced electrons generated from TiO2/g-C3N4 were harvested by microbes, optimizing the community structure of biofilms toward nitrate reduction. This study provides a new strategy to enhance the nitrate reduction in water and an insight into the reduction mechanism of nitrate in ICPB.
关键词： Intimately coupled system,Biofilms,Electrons,Photocatalysis,Nitrate
更新于2025-09-19 17:13:59
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Yield and quality of lettuce in response to the plant position in photovoltaic greenhouse
摘要： In recent years there has been an increasing spread of photovoltaic greenhouses, especially in southern European countries, due to the higher incentives recognized to solar photovoltaic (PV) panels integrated on the greenhouse roofs and/or to local laws which limit the photovoltaic systems on the ground. To maximize the income from the production of electricity, often solar panels cover 50% or more of the roof, but the shading caused by these elements on the growing surface seriously limits the productivity and affects crop development. In order to assess the effects of the spatial distribution of the solar radiation inside these structures on yield and quality of leaf vegetable crops, the response of lettuce, grown in two cycles (autumn and winter-spring), in an east-west oriented photovoltaic greenhouse with the 50% of the roof covered by PV modules was analysed. The influence of span orientation, plant position (under plastic or PV roof) and cultivar were analysed as experimental treatments in a split-split plot design with two replications. Total and marketable yield of the lettuce heads and some quality parameters (dry matter and nitrate content) were evaluated. A significant variability of the total and marketable yield due to the plant position and as consequence to the solar radiation distribution inside the structure during the growing cycle was observed. Furthermore, ranges and variability of the nitrate content of lettuce (expressed as NO3 mg kg-1 of fresh weight) were affected by the plant position and harvest season. In order to maximize yield and quality of the crops, the arrangement of plant rows and transit areas, as well as the management of nutrition, should be optimized in relation to the shading caused by the PV roof during the growing cycle.
关键词： light distribution,crop yield,leaf vegetables,nitrate content,PV panels
更新于2025-09-16 10:30:52
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Effects of LED lighting recipes on postharvest quality of leafy vegetables grown in a vertical farm
摘要： Vertical farming is a technology that controls climate, water, nutrients and light to grow food in a closed environment. This allows vegetables to grow pesticide free and without other contaminants. We investigated how to influence the postharvest quality by controlling the preharvest growth conditions while keeping a high production rate. Several standard LED lighting recipes (red/blue or red/white either with or without far red) are in use in commercial farms. For this research we used lettuce, baby leaf spinach, rocket and basil from various cultivars all grown in a vertical farm research facility. We used the standard red white LED light recipe as control, while we changed the spectrum with higher blue and/or higher far-red or apply few days of continuous light stimulation just before the harvest (preharvest). Quality at harvest and quality loss during postharvest storage was monitored. We observed that light quality affects shelf life of baby leaf spinach and rocket by several days. The best light recipe for shelf life had a high blue content (35%) while the worst was with a high far red (25%). In addition, contents of vitamin C, K, nitrate, chlorophyll and flavonols were different under various light quality. Nitrate (in lettuce, rocket and spinach) and vitamin C in rocket were strongly affected by preharvest continuous light, offering a way to reduce the nitrate and improve the antioxidant level. In addition, taste was also found to change as a function of light quality but magnitude of this change is shown to be strongly cultivar dependent.
关键词： LED lighting,nitrate,vitamin K,shelf life,vertical farming,taste,vitamin C
更新于2025-09-16 10:30:52
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Screening of microalgae and LED grow light spectra for effective removal of dissolved nutrients from cold-water recirculating aquaculture system (RAS) wastewater
摘要： Popularity of recirculating aquaculture systems (RAS) is increasing. Because of the high water recirculation rate, dissolved nutrients originating from fish feed are concentrated enough in RAS wastewater (WW) to enable growth of primary producers, e.g. microalgae. This study evaluated nitrate-nitrogen (NO3-N) and phosphate-phosphorus (PO4-P) removal efficiency of ten temperate zone freshwater microalgae species during their exponential growth phase in unfiltered RAS WW at 17 ± 0.5 °C. Growth and nutrient uptake efficiency of six green and four non-green microalgae strains were compared between WW and reference growth medium in batch monocultures. The effect of three different LED grow light spectra on growth and nutrient uptake efficiency were compared for four green microalgae in WW. The specific growth rate (SGR, 0.5-0.8 d-1) and removal of NO3-N (N%, 57–96%) and PO4-P (P%, 78–94%) of green microalgae in WW in 4 days were comparable to the results obtained in the reference medium (SGR, 0.6-0.9 d-1, N%, 59–99%; P%, 86–99%). In contrast, non-green microalgae had negligible growth (SGR, from -0.1 to 0.2 d-1) and poor nutrient removal (N%, 1–29%; P%, 0–34%) in both growth media after 9 days. The three LED spectra did not differ on their effect on growth and nutrient removal of three green microalgae in WW after 4 days, while the fourth tested species, Haematoccocus pluvialis, had its highest nutrient removal after 8 days under a specific LED spectrum. Current results show that RAS WW supports well green microalgae growth in batch cultures in temperatures common in Nordic RAS and that continuous spectrum LED grow lights can induce high removal of dissolved nutrients. Our findings lend support to the concept of using temperate zone microalgae for nutrient removal and recycling from RAS WW.
关键词： Wastewater treatment,Nitrate-nitrogen,Bioremediation,Nutrient uptake,Fish farming,Phosphate-phosphorus,Continuous light spectra,Coregonus lavaretus
更新于2025-09-12 10:27:22
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Synthesis of Perovskite Film by Using Lead Nitrate as Precursor for Perovskite Solar Cell Applications
摘要： Perovskite film is normally synthesized from lead iodide (PbI2) and methyl ammonium iodide (MAI, CH3NH3I) to form CH3NH3PbI3 perovskite film in p-i-n perovskite solar cell. However, PbI2 is difficultly dissolved for fabrication process. Lead nitrate (Pb(NO3)2) is considered as one alternative material that can be used to synthesize perovskite film with some advantages such as low cost material, non-toxic solvent requirement and water dissolvable. Thus, this study aims to synthesize perovskite film by using Pb(NO3)2 and MAI as stating materials. Spin coating method was used to deposit perovskite precursor for p-i-n perovskite solar cell fabrication. The crystal structure, surface morphology and optical property of perovskite film were investigated by X-ray diffraction, scanning electron microscope and UV-visible spectroscopy, respectively. For solar cell applications, the perovskite solar cell fabricated with Pb(NO3)2 showed lower performance than with PbI2. The low performance was resulted from the incomplete formation of perovskite film due to effects of pinhole and non-smooth film surface. However, this work demonstrated that Pb(NO3)2 has possibility to use as starting material for perovskite solar cell fabrication with non-toxic solvent process. To improve solar cell performance, perovskite film synthesized from Pb(NO3)2 should be further investigated.
关键词： Lead nitrate,perovskite solar cell,Pb(NO3)2,free-toxic solvent
更新于2025-09-11 14:15:04
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Comparison between 940 nm Laser Diode and Topical 5 % Potassium Nitrate for Tooth Desensitization. Randomized Controlled Clinical trial
摘要： Purpose: To compare the effectiveness of two dental desensitization therapies, 940nm laser diode and potassium nitrate, in patients with dental hypersensitivity (DH) symptoms. Methods: This randomized clinical trial included 30 patients who initially underwent basic periodontal therapy and presented gingival recessions Class I and II (Miller 1985) with symptoms of DH. Subjects were randomly assigned into two groups. The first group (n = 15) received laser 940 nm application for 90 seconds on the surface of the recession and were given a tube of glycerin to be applied daily in order to avoid generating bias. Patients in the second group (n = 15) were exposed to inactive laser simulating the actual application of the laser, and they were given a desensitizing gel containing 0.5 g of potassium nitrate to be applied twice daily during 14 days. Controls were carried out at 15 minutes, 8 days, 15 days, and 4 weeks. Data obtained were filled out in an Excel table. For comparison between groups the Mann Whitney U and t student tests were used (p=0.05). Results: All patients involve in the study experienced reduction in DH (p<0.01) and differences between the two interventions performed. Conclusions: Laser and nitrate therapies were effective to manage DH after basic periodontal therapy. However, a statistically significant higher sensitivity reduction was observed in laser therapy group.
关键词： diode laser,dentinal sensitivity,periodontal disease,gingival recession,potassium nitrate
更新于2025-09-11 14:15:04
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Using Terahertz Spectrometry to Study the Thermal Decomposition of Energy Materials
摘要： This paper describes experimental results on using nonstationary spectrometry in a terahertz frequency range to determine the composition of gaseous products of decomposition of energy materials. Dependences of analytical signals on lines of the main products of ammonium nitrate and PETN decomposition on time are obtained.
关键词： terahertz spectrometry,energy materials,ammonium nitrate,PETN,thermal decomposition,decomposition kinetics,decomposition products
更新于2025-09-11 14:15:04
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Synthesis of silver nanoparticles by atmospheric-pressure pulsed discharge plasma in a slug flow system
摘要： Application of nonequilibrium atmospheric-pressure plasma has been proven as a medium for silver particle formation in slug flow reactor systems. Argon gas was introduced in the slug flow reactor system in the gas phase. In the liquid phase, silver nitrate (AgNO3) with and without the addition of starch was dissolved in distilled water. The flow rates of the liquid and gas phases were 1.5 and 0.15 ml min?1, respectively. A yellow-colored solution product was obtained when the feed solution containing starch was fed. The optical emission spectrum showed that silver atoms were detected clearly at 328 nm. The ultraviolet–visible spectroscopy analysis showed that the solution products seemed to absorb light between 380 and 440 nm, corresponding to silver nanoparticle generation. Transmission electron microscopy revealed that the monodispersed silver nanoparticles were formed in a spherical morphology with diameter less than 10 nm on average. ? 2018 The Japan Society of Applied Physics
关键词： atmospheric-pressure pulsed discharge plasma,starch,silver nitrate,silver nanoparticles,slug flow system
更新于2025-09-10 09:29:36
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Investigations on synthesis, growth and physicochemical properties of semi-organic nonlinear optical crystal: l-arginine sodium nitrate
摘要： Single crystals of l-arginine sodium nitrate semiorganic nonlinear optical crystal were grown by slow evaporation process at room temperature. The single crystal X-ray diffraction study confirms that the unit cell parameters of the grown l-arginine sodium nitrate crystal. Fourier transform infrared spectrum analysis was used to identify the functional groups of the grown crystal. The thermal stability of the l-arginine sodium nitrate was determined using thermogravimetric analysis and differential thermal analysis. The linear optical property of LARSN crystal has been studied using Ultraviolet–visible spectroscopy studies in the wavelength range 200–800 nm. The relative second harmonic efficiency of the l-arginine sodium nitrate compound is found to be 0.49 times that of Potassium Di-hydrogen phosphate. The mechanical property of the grown crystals was determined by Vicker’s micro hardness test and it proved the hard nature of the grown crystal. Dielectric study reveals that both dielectric constant and dielectric loss decreases with increase in frequency.
关键词： thermal analysis,l-arginine sodium nitrate,slow evaporation process,FTIR,nonlinear optical crystal,microhardness,dielectric properties,X-ray diffraction,SHG efficiency,UV–Vis spectroscopy
更新于2025-09-10 09:29:36