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- 2018
- sodium lighting system
- modeling
- radiation curves
- LED lighting system
- software goniophotometer
- upper half-space
- Electrical Engineering and Automation
- VSB-TU Ostrava
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Na-mediated stoichiometry control of FeS <sub/>2</sub> thin films: suppression of nanoscale S-deficiency and improvement of photoresponse
摘要： Control of the constituent phase and stoichiometry of iron pyrite (FeS2) is a prerequisite for high-performance photovoltaic devices based on this material. If the pyrite contains sulfur-deficiency-related secondary phases, which have a metallic character and a high possibility of coexistence in pyrite films, significant carrier recombination is expected. In this work, the beneficial role of Na in suppressing the formation of nanoscale or amorphous sulfur-deficient secondary phases is reported with experimental evidence, leading to a higher phase purity for solution-processed pyrite films. The potential reduction of charge recombination via these metallic secondary phases results in significant improvements in both the photopotential and photocurrent intensity of Na-modified pyrite films compared with reference samples.
关键词： solar cell,sodium (Na),S deficiency,pyrite (FeS2),secondary phases
更新于2025-09-11 14:15:04
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Effectiveness of photodynamic therapy and sodium hypochlorite on root canal system infected with Enterococcus faecalis – An in vitro study
摘要： Objective: The purpose of this study was to evaluate, in vitro, the effectiveness of photodynamic therapy and sodium hypochlorite over root canal system infected with Enterococcus faecalis. Methods: The root canals of 45 single-rooted human extracted teeth were enlarged up to a file 60, autoclaved, inoculated with Enterococcus faecalis and incubated for 30 days. The samples were divided into five groups (G1 – n=5; G2-G5 – n=10) according to the protocol of decontamination: G1 (negative control) – no procedure was performed; G2 – distilled water; G3 – photodynamic therapy (PDT); G4 – 2.5% sodium hypochlorite (NaOCl); and G5 – 2.5% NaOCl+PDT. Scanning electron microscopy (SEM) were performed to evaluate the effectiveness of proposed treatments. The assessment was made by images of each third at 5000x magnification for the canal wall and 10000x for the exposed tubule area. The presence of bacteria was scored by position ranks from 1 to 45, where the higher the value, the cleanliness of the sample. Data were subjected to one-way ANOVA followed by post-hoc Tukey test (α=0.05). Results: Group 4 (2.5% NaOCl) and 5 (2.5% NaOCl + PDT) had the highest mean of position ranks for all thirds of the root canal in the canal wall, which was statistically different from groups 1, 2 and 3 (p<0.05). Group 3 (PDT), group 4 (2.5% NaOCl) and 5 (2.5% NaOCl+PDT) had the highest mean of position ranks in the exposed tubule area, which was statistically different from groups 1 and 2 (p<0.05). Conclusion: the association of 2.5% sodium hypochlorite + photodynamic therapy can be considered an effective protocol for the elimination of Enterococcus faecalis.
关键词： Photodynamic therapy,Sodium hypochlorite,Enterococcus faecalis
更新于2025-09-11 14:15:04
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A green one-pot approach for mesoporous g-C3N4 nanosheets with in situ sodium doping for enhanced photocatalytic hydrogen evolution
摘要： Synchronous nano-structuring and element-doping of g-C3N4 were realized via a green one-pot approach to improve its photocatalytic activity. Na-doped mesoporous g-C3N4 nanosheets of ~5 nm in thickness were facilely synthesized by calcining a mixture of dicyandiamide and sodium chloride. NaCl not only serves as a con?ning-reactor to con?ne the growth of g-C3N4 into mesoporous nanosheets, but also acts as a sodium source for Na-doping. The nanosheets own greater speci?c surface area, stronger optical absorption and lower recombination of photo-induced electron-hole pairs than bulk g-C3N4, and exhibit an excellent visible-light photocatalytic hydrogen evolution ef?ciency which is about 13 times that of bulk g-C3N4. Moreover, the thermostable and hydrosoluble NaCl is simply removed and recycled by water and then directly reused in a new synthesis, making the process to be environmental-friendly and sustainable.
关键词： g-C3N4,Sodium chloride,Photocatalytic hydrogen evolution,Sodium doping,Mesoporous nanosheet
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
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Metal-free visible-light photocatalytic tandem radical addition-cyclization strategy for the synthesis of sulfonyl-containing isoquinolinediones
摘要： A mild radical cascade reaction for the synthesis of sulfonyl-containing isoquinolinediones has been developed, in which sulfonyl radicals can be accessed from simple sodium sulfinates under visible light and eosin Y catalysis. This tandem approach features a broad range of substrates and functional group tolerance. With this strategy, trifluoromethylated isoquinolinedione was also obtained.
关键词： radical reaction,photocatalysis,cycloaddition,eosin Y,sodium sulfinate
更新于2025-09-10 09:29:36
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Synthesis and characterization of SDS assistant α-alumina structures and investigation of the effect of the calcination time on the morphology
摘要： In this paper, α-alumina structures were successfully prepared via hydrothermal synthesis supported with sodium dodecyl sulfonate anionic surfactant. The effect of the surfactant and the calcination time were investigated. The characterization of the samples calcinated at 1200 °C was performed using Raman spectroscopy, X-Ray Difraction analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy techniques. Experimental results showed that pure α-Al2O3 structures were obtained with different morphologies.
关键词： Hydrothermal synthesis,Calcination,Morphology,Sodium dodecyl sulfonate,Alumina
更新于2025-09-10 09:29:36
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Enhanced photocatalytic Cr(VI) reduction and diclofenac sodium degradation under simulated sunlight irradiation over MIL-100(Fe)/g-C3N4 heterojunctions
摘要： Metal-organic framework MIL-100(Fe) and g-C3N4 heterojunctions (MG-x, x = 5%, 10%, 20%, and 30%, x is the mass fraction of MIL-100(Fe) in the hybrids) were facilely fabricated through ball-milling and annealing, and characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, UV-visible diffuse-reflectance spectrometry, and photoluminescence emission spectrometry. The photocatalytic activities of the series of MG-x heterojunctions toward Cr(VI) reduction and diclofenac sodium degradation were tested upon irradiation with simulated sunlight. The influence of different organic compounds (ethanol, citric acid, oxalic acid, and diclofenac sodium) as hole scavengers and the pH values (2, 3, 4, 6, and 8) on the photocatalytic activities of the series of MG-x heterojunctions was investigated. MG-20% showed superior photocatalytic Cr(VI) reduction and diclofenac sodium degradation performance than did the individual MIL-100(Fe) and g-C3N4 because of the improved separation of photoinduced electron-hole charges, which was clarified via photoluminescence emission and electrochemical data. Moreover, the MG-x exhibited good reusability and stability after several runs.
关键词： MIL-100(Fe),Cr(VI) reduction,g-C3N4,Heterojunction,Diclofenac sodium
更新于2025-09-10 09:29:36
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An affordable photocatalyst for pharmaceuticals and superior electro catalyst for methanol oxidation - A dual role by CuWO4 anchored bentonite clay
摘要： In this present study, we developed a novel bentonite loaded CuWO4 nanoparticles (BEN-CuWO4 NPs) through the simple hydrothermal method. The as-prepared BEN-CuWO4 NPs was systematically characterized by various spectroscopic techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, Field emission scanning electron microscopy (FESEM), High resolution transmission electron microscopy (HR-TEM), DRS-UV visible spectroscopy, Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) techniques. For the first time, the BEN-CuWO4 NPs were utilized as a bifunctional catalyst for the photodegradation of Diclofenac sodium (DFS) and electrooxidation of methanol. More distinctively, the BEN-CuWO4 NPs exhibited excellent photocatalytic activity could degrades above 94% DFS solution under visible light illumination with superior stability. Further, BEN-CuWO4 NPs portrayed superior electrocatalytic activity for the oxidation of methanol when compared to the pristine CuWO4. In addition, Impedance studies revealed that the BEN-CuWO4 NPs holds the tremendous dielectrical properties. This present investigation opens a new door way for the synthesis of multifunctional nanostructured materials for practical energy and environmental applications.
关键词： Photo degradation,Electrochemical studies,Bentonite clay,Copper tungstate,Hydrothermal,Diclofenac sodium
更新于2025-09-10 09:29:36
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Synchronous enhancement and stabilization of graphene oxide liquid crystals: Inductive effect of sodium alginates in different concentration zones
摘要： A facile way to simultaneously induce the formation and enhance the stability of graphene oxide liquid crystals (GO LCs) is reported. Sodium alginate (SA) with both inductive effect and stabilization effect was added into GO suspensions to prepare LCs at low concentration that could survive harsh conditions. Most importantly, different concentration zones of SA brought significantly different LCs degree and stability, which possessed distinct charge properties, rheological behaviors and chain morphology. Adding 0.5 % SA located in entangled semi-dilute regime could induce the isotropic-nematic transition of GO at low concentration (< 0.035 %) and showed excellent liquid crystalline behavior due to the enhanced electrostatic repulsion of GO/SA colloids, while 1% SA located in concentrated solution regime brought better tolerance to NaCl, MgCl2, FeCl3, serum and pH of 1-13 due to the stronger bounding effect of entanglement network structure to countra-ions. This work develops a simple and eco-friendly method to prepare stable GO LCs at low GO concentration with application potentials especially in biomedical field, and the relationship between the concentration zones of SA and LCs behavior offers theoretical guidance for the self-assembly of GO macrostructures and design and efficient processing of its composites.
关键词： Sodium alginate,Liquid crystals,Graphene oxide
更新于2025-09-10 09:29:36
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Study of Bi-directional detection for ascorbic acid and sodium nitrite based on Eu-containing luminescent polyoxometalate
摘要： Eu-containing polyoxometalate K13Eu(SiMoW10O39)2·28H2O (Eu-SiMoW) owns the stimu-chromic and photo-luminescence properties. An ingenious test of ascorbic acid (AA) and sodium nitrite (NaNO2) was carried out based on the dual properties of Eu-SiMoW in solutions. First, the redox reaction of Eu-SiMoW and AA generated the blue reduced Eu-SiMoW, accompanied by fluorescence quenching; then the redox reaction of the reduced Eu-SiMoW and NaNO2 made Eu-SiMoW back to its original pale yellow state with red luminescence. Accordingly, the content of AA and NaNO2 could be measured by the reversible change of color and luminescence of Eu-SiMoW. This bi-directional detection method is first discovered and proven to be a simple and effective method for the detection of AA and NaNO2. The proposed method exhibited a linear response range (LRR) from 0.1 to 0.9 mmol L?1 with a limit of detection (LOD) of 0.53 μmol L?1 in UV–vis spectra and 4.67 μmol L?1 in luminescence spectra for AA as well as a LRR from 0.05 to 0.4 mmol L?1 with a LOD of 1.16 μmol L?1 in UV–vis spectra and 5.39 μmol L?1 in luminescence spectra for NaNO2. Moreover, the fluorescence switching of Eu-SiMoW could be realized by reacting with reductant and oxidant through the redox reaction. The detection mechanism is considered as a fluorescence resonance energy transfer process between discolor component SiMoW and luminescence component Eu in Eu-SiMoW.
关键词： Ascorbic acid,Sodium nitrite,Bi-directional detection,Eu-polyoxometalate,Luminescence switching
更新于2025-09-10 09:29:36