•A novel Dy3+doped MgP2O6 phosphor is synthesized via combustion route.•The Rietveld refinement method is used to calculate the lattice parameters.•Photometric results shows the emission profile in ...yellow-whitish region.•The synthesized phosphor is a potential candidate for WLED applications.
A yellowish white light emitting Dy3+ (0.5, 1, 1.5, 2, and 2.5 mole%) activated MgP2O6 phosphors were prepared using Solution combustion (SC) method. The X-ray diffraction (XRD) and Rietveld refinement confirmed the phase purity with “monoclinic symmetry” having space group P21/n. The lattice constant of the optimum doped sample is also refined by “Full Prof software”. Photoluminescence (PL) spectroscopy was employed to observe the luminescent properties, including both excitation and emission features. The phosphor verified intense yellowish emission at 573 nm, analogous to the hypersensitive electric dipole transition4F9/2→6H13/2. The critical activated concentration of MgP2O6:Dy3+ phosphor approximately occurs at 1.5 mole%. The phosphor exhibits conventional applications in solid-state lighting when excited under UV light at 348 nm.
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Spectroelectrochemistry (SEC) enables
in-operando
UV–vis study of electrochemical cells to explore the evolution of different cell components and understand cell mechanisms. Researchers have ...demonstrated various custom UV–vis cell designs to accommodate SEC experiments. However, existing designs do not easily permit temperature ramp techniques to examine the effects of rapidly changing cell temperature or high temperature conditions on cell mechanisms. This communication presents two easy-to-replicate, low-cost cell designs that are incorporable with existing UV–vis systems (transmittance, reflectance) and enable high temperature, rapid heating SEC experiments. Each cell design was tested to evaluate temperature ramp and sealing performance.
•Photocatalytic membrane reactors with suspended and immobilized N-TiO2 were used for diclofenac removal.•Coupling H2O2 with the photocatalytic process could enhance the DCF removal ...efficiency.•Coupling H2O2 with the photocatalytic process yielded higher resistant permeate flux rates.
A submerged photocatalytic membrane reactor (SPMR) was used with suspended and immobilized N–TiO2 under visible irradiation for diclofenac (DCF) removal from wastewater. The effects of initial N–TiO2 concentrations for the SPMR with suspended N–TiO2 were determined for batch processes. Hydrogen peroxide was also coupled with the photocatalytic process. In continuous conditions, a reverse osmosis (RO) membrane was combined with the SPMR for enhancing effluent quality. DCF removal by the SPMR with suspended and immobilized N–TiO2 at a low N–TiO2 dosage (0.5g/L) was not much different between the two systems, but increased with higher N–TiO2 dosages for the reactor with suspended N–TiO2. Coupling H2O2 with the photocatalytic process under visible irradiation enhanced the DCF removal efficiency. In continuous conditions, DCF concentrations in the photoreactor increased during the reaction time, while those in the effluent (RO permeate) were steady for both systems and both processes. The permeate flux in the reactor with suspended N–TiO2 declined faster than in the reactor with the immobilized N–TiO2. Coupling H2O2 with the photocatalytic process yielded more resistant permeate flux rates. The cake layer formed on the microfiltration membrane of the SPMR with suspended N–TiO2 under visible irradiation was denser than others after completing the process.
UV–Vis can be used as an easy and forthright technique to accurately estimate the band gap energy of organic π-conjugated materials, widely used as thin films/composites in organic and hybrid ...electronic devices such as OLEDs, OPVs and OFETs. The electronic and optical properties, including HOMO–LUMO energy gaps of π-conjugated systems were evaluated by UV–Vis spectroscopy in CHCl3 solution for a large number of relevant π-conjugated systems: tris-8-hydroxyquinolinatos (Alq3, Gaq3, Inq3, Al(qNO2)3, Al(qCl)3, Al(qBr)3, In(qNO2)3, In(qCl)3 and In(qBr)3); triphenylamine derivatives (DDP, p-TTP, TPB, TPD, TDAB, m-MTDAB, NPB, α-NPD); oligoacenes (naphthalene, anthracene, tetracene and rubrene); oligothiophenes (α-2T, β-2T, α-3T, β-3T, α-4T and α-5T). Additionally, some electronic properties were also explored by quantum chemical calculations. The experimental UV–Vis data are in accordance with the DFT predictions and indicate that the band gap energies of the OSCs dissolved in CHCl3 solution are consistent with the values presented for thin films.
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•Solution absorption spectra of low molecular weight conjugated systems typically used in thin films of semiconductors are presented.•UV–Vis can be used as an easy and straightforward technique to accurately estimate the band gap energy of organic π-conjugated semiconductors.•The band gap energies of the OSCs dissolved in CHCl3 solution are consistent with the values presented for thin films.
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•Oxygen vacancies were induced into ZnFe2O4 nanospheres by thermal treatment.•ZnFe2O4 nanospheres with oxygen vacancies can effectively activate peroxodisulfate.•Oxygen vacancies ...improve the charge transfer process in the ZFOV/PDS/vis system.•ZnFe2O4 with oxygen vacancies exhibits good reusability and stability.
Water pollution is a global environmental problem that needs to be solved urgently. Among them, visible light-assisted catalytic peroxodisulfate (PDS) activation, as an efficient advanced oxidation technology, has great potential in organic wastewater treatment. Therefore, it is crucial to develop efficient photocatalysts based on PDS activation. Here, introducing defects in ZnFe2O4 to construct abundant oxygen vacancies (ZFOV) could not only promote the photocatalytic degradation of TCH, but also enhance magnetic nanoparticles-activated PDS. It was shown that the ZFOV/PDS/vis system could degrade TCH by ∼ 65 % within 30 min, about 1.23 times greater than that of ZFO/PDS/vis system. More importantly, the degradation rate was still over 58 % after three reuse cycles and extremely low leaching of Zn and Fe were observed. The effects of pH, PDS concentration, humic acid, anions and cations on TCH degradation in the presence of ZFOV/PDS/vis systems were also investigated in detail. Combining experimental results revealed that oxygen vacancies acted as catalytically centers which supplied abundant local electrons for the adsorbed S2O82− reaction to produce OH and SO4− via a single electron transfer process. Additionally, oxygen vacancies could also boost electron transfer and take part in the Fe2+/Fe3+ redox cycle. Our study might open up new avenues for designing high efficiency photocatalyst by means of surface engineering and PDS activation.
Abstract
C
60
–bodipy triads and tetrads based on the energy‐funneling effect that show broadband absorption in the visible region have been prepared as novel triplet photosensitizers. The new ...photosensitizers contain two or three different light‐harvesting antennae associated with different absorption wavelengths, resulting in a broad absorption band (450–650 nm). The panchromatic excitation energy harvested by the bodipy moieties is funneled into a spin converter (C
60
), thus ensuring intersystem crossing and population of the triplet state. Nanosecond time‐resolved transient absorption and spin density analysis indicated that the T
1
state is localized on either C
60
or the antennae, depending on the T
1
energy levels of the two entities. The antenna‐localized T
1
state shows a longer lifetime (
τ
T
=132.9 μs) than the C
60
‐localized T
1
state (ca. 27.4 μs). We found that the C
60
triads and tetrads can be used as dual functional photocatalysts, that is, singlet oxygen (
1
O
2
) and superoxide radical anion (O
2
.
−
) photosensitizers. In the photooxidation of naphthol to juglone, the
1
O
2
photosensitizing ability of the C
60
triad is a factor of 8.9 greater than the conventional triplet photosensitizers tetraphenylporphyrin and methylene blue. The C
60
dyads and triads were also used as photocatalysts for O
2
.
−
‐mediated aerobic oxidation of aromatic boronic acids to produce phenols. The reaction times were greatly reduced compared with when Ru(bpy)
3
Cl
2
was used as photocatalyst. Our study of triplet photosensitizers has shown that broadband absorption in the visible spectral region and long‐lived triplet excited states can be useful for the design of new heavy‐atom‐free organic triplet photosensitizers and for the application of these triplet photosensitizers in photo‐organocatalysis.
In this study, graphene oxide (GO) nanosheets were synthesized by the modified Hummers method. GO structure was estimated by XRD, UV–vis-spectrophotometer and SEM imaging. Then homogeneous and stable ...GO/water nanofluid was prepared. The effects of GO concentration and temperature on the thermal conductivity were investigated.
The measurements of thermal conductivity indicate that the nanofluids have substantially higher thermal conductivities than the base fluid.
The thermal conductivity enhancement depends strongly on the concentration of GO and increases with the increasing loading. When the nanosheet loading is 0.25wt.%, the enhancement ratio is 33.9% at 20°C and when the temperature increased to 40°C the enhancement is up to 47.5%. Therefore the level of enhancement is dependent of temperature in the measured temperature range.
Plants extract from Ocimum tenuiflorum, Solanum tricobatum, Syzygium cumini, Centella asiatica and Citrus sinensis was used for the synthesis of silver nanoparticles (Ag NPs) from silver nitrate ...solution. Ag NPs were characterized by UV–vis spectrophotometer, X-ray diffractometer (XRD), atomic force microscope (AFM) and scanning electron microscope (SEM). The formation and stability of the reduced silver nanoparticles in the colloidal solution were monitored by UV–vis spectrophotometer analysis. The mean particle diameter of silver nanoparticles was calculated from the XRD pattern according to the line width of the plane, refraction peak using the Scherrer’s equation. AFM showed the formation of silver nanoparticle with an average size of 28 nm, 26.5 nm, 65 nm, 22.3 nm and 28.4 nm corresponding to O. tenuiflorum, S. cumini, C. sinensis, S. tricobatum and C. asiatica, respectively. SEM determination of the brown color stable samples showed the formation of silver nanoparticles and well dispersed nanoparticles could be seen in the samples treated with silver nitrate. Antimicrobial activity of the silver bio-nanoparticles was performed by well diffusion method against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. The highest antimicrobial activity of silver nanoparticles synthesized by S. tricobatum, O. tenuiflorum extracts was found against S. aureus (30 mm) and E. coli (30 mm) respectively. The Ag NPs synthesized in this process has the efficient antimicrobial activity against pathogenic bacteria. Of these, silver nanoparticles are playing a major role in the field of nanotechnology and nanomedicine.
•The typical Vis-NIR spectrum of green leaves is accurately simulated with an easy preparation and cost-effective method.•Solid polyurethane microcapsules encapsulating liquid water (W-PUMCs) were ...prepared.•W-PUMCs simulate the spectral characteristics of water in green leaves, with a similarity of 0.9930 in 1100–2200 nm.•The epoxy doped with W-PUMCs and Cr2O3 can simulate leaves’ spectra, with a similarity of 0.9779 in 400–2500 nm.
Targets can achieve invisibility in the vegetation environments by simulating the reflection spectra of plant green leaves. However, balancing the accuracy and stability of simulation effects, particularly in simulating spectral features caused by water in the leaves, is often challenging. Herein, polyurethane microcapsules encapsulating liquid water (W-PUMCs) were prepared by inverse emulsion polymerization, then mixed with Cr2O3 in specific proportions into the epoxy resin matrix to obtain a material capable of simulating the reflection spectra of green leaves in the visible and near-infrared bands. The normalized similarity (NS) between the spectrum of this material and that of plant (cherry) green leaf can reach 0.9779 in the range of 400–2500 nm. W-PUMCs are used to simulate the spectral characteristics caused by water in the leaves because the spectral NS between W-PUMCs and the green leaf in the 1100–2200 nm range is 0.9930. Cr2O3 is employed to simulate the other major spectral features of green leaves. This strategy guarantees simulation accuracy while simplifying the preparation process and reducing production costs and providing solutions to spectral simulation in the fields of military stealth and ecological protection.
Today’s employee has to prepare himself for all possible ways to interact with people, be it in person, video conference, tele-conference, Skype, presentation, etc. It becomes inevitable for today’s ...aspiring Engineers to jump in for key posts in the corporate world to master their presentation skills. The need for our students to excel in presentation skill prompted us to go for a small experiment with a sample size of 10 freshman students. After we had a detailed discussion with the stakeholders (HODs, Placement officer, Deans and sample group of students) on campus before revisiting the Professional Communication course content which is delivered to the freshman students; we learnt that our students required an immediate intervention in improving their presentation skills. This prompted us to research and go in for a pedagogical experiment. This paper talks about the approach that was coined in detail after years of teaching Professional Communication Course for freshman students of Engineering at KLE Technological University, Hubli. We called it The Vis-a-Vis Approach as Vis-a-Vis basically is a French word which means “face to face”. This approach was coined keeping in mind as to help the students know themselves and their shortcomings better through a thorough discussion which happens one on one between the faculty and the student away from the class environment after the assessments. The discussion actually begins by getting to know the students and his life and his parents back home and his hobbies. This personal touch opened the gates to make student realize their shortcomings as far as the presentations were concerned more meaningfully.
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