Excitation Peak Research Articles

Enhancing the discharge uniformity of atmospheric pressure DBD cold plasma for food efficient microbial inactivation

Identification and optimization of the discharge uniformity is worldwide problems in the plasma industry. In this study, a simple, practical, and economical alternative for quantitatively identifying discharge uniformity of DBD plasma was proposed using the gray-level histogram, discharge area curve, and gray level transformation characteristics of discharge images. The influences of discharge peak voltage, excitation frequency, dielectric material, and dielectric thickness on discharge uniformity on the time scale of seconds were discussed, and the intrinsic relationship and mechanism between discharge uniformity and microbial inactivation efficiency were revealed. Within a certain range, with the gradual increase of discharge peak voltage (13–17 kV), excitation frequency (9–11 kHz), relative dielectric constant (3.6–9.6), and the gradual decrease of dielectric thickness (1–5 mm), the discharge image corresponded to the relative discharge uniformity and the average inactivation of L. monocytogenes and S. typhimurium (0.12–1.40 log-reduction and 0.26–2.34 log-reduction) increased as a whole. Overall, the findings revealed disruption or improvement of the discharge uniformity was the main factor contributing to the inactivation of bacteria by cold plasma, facilitating the scaling-up of DBD reactors on an industrial scale.

A well-performed green-emitting Lu1.5Ca1.5Al3.5Si1.5O12:Ce3+ garnet phosphor for high-quality pc-WLEDs

High-brightness and thermally-stable broadband green-emitting phosphors are highly demanded for the fabrication of high-quality phosphor-converted white light-emitting diodes (pc-WLEDs) with high color rendering index (CRI) and low correlated color temperature (CCT). Herein, we report on the synthesis, luminescent properties, thermal stability and application of a novel highly efficient green-emitting Lu1.5Ca1.5Al3.5Si1.5O12:Ce3+ garnet-type phosphor for blue-chip-pumped high-CRI pc-WLEDs. A series of Lu1.5Ca1.5Al3.5Si1.5O12:Ce3+ green phosphors doped with various Ce3+ concentrations (0.5-4 mol%) have been prepared by a conventional high-temperature solid-state reaction approach. Impressively, the composition-optimized Lu1.5Ca1.5Al3.5Si1.5O12:2%Ce3+ sample exhibits a broad excitation band in the 400-500 nm spectral range with an excitation peak around 451 nm, and it gives rise to a bright broad green emission band in the 470-700 nm wavelength region (emission peak: 533 nm; bandwidth: 108 nm) with CIE color coordinates of (0.3361, 0.5640). Notably, high luminescence efficiency is obtained for Lu1.5Ca1.5Al3.5Si1.5O12:2%Ce3+ phosphor (internal quantum efficiency: 92.2%; external quantum efficiency: 50.7%). Moreover, it is also found that Lu1.5Ca1.5Al3.5Si1.5O12:2%Ce3+ shows excellent resistance to thermal quenching, while its emission intensity at 423 K remains 76% of the initial value at room temperature. Amazingly, the color stability of Lu1.5Ca1.5Al3.5Si1.5O12:2%Ce3+ is also outstanding, and only a very small chromaticity shift (3.99 × 10−3) is observed at 423 K. A high-performance pc-WLED device has been fabricated by using a 450 nm blue-emitting LED chip and as-prepared Lu1.5Ca1.5Al3.5Si1.5O12:2%Ce3+ green phosphor as well as commercial CaAlSiN3:Eu2+ red phosphor. Such device produces a bright warm-white emission under 280 mA driving current, demonstrating super CIE chromaticity coordinates (0.3870, 0.3818), high CRI of 93.8, low CCT of 3865 K, and high luminous efficacy (51.86 lmW-1).

Sub-∘C-precision temperature imaging using phase-shift luminescence thermometry

Abstract This work explores the potential of luminescence thermometry to provide temperature imaging with high temperature resolution using the phase-shift method. Phosphor thermometry has been widely used for temperature imaging, especially with the decay-time method. However, the phase-shift method was rarely used. In this approach, excitation is modulated in time, and due to the temperature-dependent luminescence dynamics of the painted luminescent probe, the emission waveform is phase-shifted with respect to the excitation waveform. Initially, a parametric study was performed on the effect of excitation waveform frequency and shape, based on a millisecond-decay time phosphor. The study found that the best precision is achieved with a square waveform at a frequency such that the phase shift is π 4 at the target temperature. Then, this method was compared with the well-established decay-time method. Phase-shift method offered a three-fold improvement in temperature precision under identical peak excitation power. Finally, two-dimensional measurements were demonstrated on a temperature-controlled plate using a high speed CMOS camera, and an LED illumination. A temperature precision of 0.13 ∘C was obtained at a temporal resolution of 0.25 s and a spatial resolution of around 1 mm, due to a pre-processing binning of 7 by 7 pixels. This technique can be used as a robust alternative to infrared thermometry to probe the thermal processes with small temperature differences.

Control resonant excitation of surface plasmon polariton in quantum-dot molecule system via tunneling induced transparency and Autler–Townes splitting

Electromagnetic induced transparency (EIT) and Autler–Townes splitting (ATS) both produce a transparency window in an absorption profile, yet EIT is distinct in that it can create a transparency window for a weak control field. To elucidate the distinct physical mechanisms underlying EIT and ATS effects, we explore the controlled resonant excitation of surface plasmon polaritons (SPPs) within these regimes. Our setup is composed of three layers: a top vacuum or air layer, a central metal film, and a bottom layer of dielectric medium based on the quantum-dot molecules (QDMs) system. Unlike typical systems, that employ prism or grating coupling scheme, our setup takes advantage of the unique features of the QDMs medium to investigate the direct resonance excitation of SPPs. A weak probe and a strong control field are carried through air or vacuum to the top layer. Our results demonstrate that the permittivity of the bottom medium displays tunneling induced transparency (TIT) if the tunneling strength (Te) and the decay rate of the direct exciton (Γ1) follow the condition Te/Γ1⩽0.5; otherwise, it represents the ATS effect. In both instances, the permittivity of the QDMs medium satisfy the low-loss (high transmission) criteria, i.e., Re [ɛd]<1 and Im [ɛd]≪1, providing a framework for exploring the control resonant excitation of SPPs. We simulate the reflection and transmission spectra using the Fresnel’s formula and noticed sharp dips in reflection and peaks in the transmission spectra, which are the signature of coupler free resonance excitation of SPPs. We noticed that the narrow peak in TIT allows for strong light transmission and thus a high peak in SPP resonance excitation, resulting in higher sensitivity in plasmonic sensors. Conversely, the large spacing between the two peaks in the ATS effect broadens the range of effective excitation frequencies for SPPs, increasing the system’s adaptability and efficiency in applications requiring broad spectrum responses.

Evidence for ecological tuning of anuran biofluorescent signals

Although biologists have described biofluorescence in a diversity of taxa, there have been few systematic efforts to document the extent of biofluorescence within a taxonomic group or investigate its general significance. Through a field survey across South America, we discover and document patterns of biofluorescence in tropical amphibians. We more than triple the number of anuran species that have been tested for this trait. We find evidence for ecological tuning (i.e., the specific adaptation of a signal to the environment in which it is received) of the biofluorescent signals. For 56.58% of species tested, the fluorescence excitation peak matches the wavelengths most abundant at twilight, the light environment in which most frogs are active. Additionally, biofluorescence emission spans both wavelengths of low availability in twilight and the peak sensitivity of green-sensitive rods in the anuran eye, likely increasing contrast of this signal for a conspecific receiver. We propose an expanded key for testing the ecological significance of biofluorescence in future studies, providing potential explanations for the other half of fluorescent signals not originally meeting formerly proposed criteria. With evidence of tuning to the ecology and sensory systems of frogs, our results suggest frog biofluorescence is likely functioning in anuran communication.

Age and initial position affect movement biomechanics in sit to walk Transitions: Lower limb muscle Activity and joint moments

Facilitating forward movement while maintaining dynamic stability during transitions like sit-to-walk (STW) requires coordination from many muscles. Age-related muscle, sensory, and neural decline can introduce compensatory biomechanics when completing STW, such as adjusting initial foot position or rising with arm support. Many previous STW studies restrict arm movement and prescribe symmetric foot positions, therefore the purpose of this study was to quantify lower limb muscle excitations and joint moments in STW transitions from four initial foot positions [symmetric, posterior offset, wide, narrow] and two arm placements [hands on knees, arms folded] in 15 younger and 15 older adults. Peak knee and ankle joint extension moments, as well as peak electromyography of five bilateral lower-limb muscles were analyzed. In all conditions, older adults had larger knee extension moments, whereas younger adults had larger ankle plantarflexion moments. Older adults generated larger peak excitation from the knee extensor muscles during rising compared to younger adults, consistent with the higher knee extension moments. Older adults had greater peak dorsiflexor and plantarflexor muscle excitation while rising compared to younger adults. Posterior offset and wide foot positions required the largest peak ankle plantarflexion and knee extension moments and plantarflexor muscle excitation. Arm-supported rising decreased peak knee extensor muscle excitation. In addition, there were interaction effects between age and initial foot position/arm placement for multiple quantities, indicating that the effects of foot and arm placement vary with age. These results inform assessments of movement performance and guidelines for rising given individual lower limb capability.

Investigation on luminescent characteristics of Tb3+/Dy3+co-doped boro-phosphate glass for cool white LED and radiation shielding applications

The Tb3+/Dy3+ co-doped Boro-Phosphate Glass (BPANZDyTb) was produced (40 B2O3 + 39P2O5 + 5 Al2O3 + 5 NaF + 10 ZnO + 0.5 Tb2O3 + 0.5 Dy2O3) using melt-quenching technique. X-ray diffraction measurements, Raman, and Fourier Transform Infrared were used to evaluate the structural behavior of the prepared glass. Powder-XRD spectra, in the 10–90° range showed that the prepared glass was amorphous. FTIR analysis reveals that the network contains a variety of structural groups, including B-O-B, BO4, BO, P-O, PO2, P-O-B, and PO4 units. The UV–visible diffuse reflectance spectroscopy was used to record and study the optical linear properties of Tb3+/Dy3+ co-doped Boro-Phosphate Glass (BPANZDyTb). The photoluminescence excitation peak was obtained at 348 nm. The emission peaks were located at 484 nm (4F9/2 → 6H15/2 → blue), 576 nm (4F9/2 → 6H13/2 → yellow), and 662 nm (4F9/2 → 6H11/2 → red). Tb3+ ions are located at 412 nm (5D3 → 7F5), 441 nm (5D3 → 7F4), 546 nm (5D4 → 7F5), and 625 nm (5D4 → 7F3). The result of CIE 1931 chromaticity coordinates indicate that the prepared glass is suitable material for cold white light emitting diode applications due to its color coordinates x = 0.3106 and y = 0.3240 and correlated color temperature (CCT) values about 6768 K. The gamma-ray parameters such as half-value layer (HVL), mass attenuation coefficient (μ/ρ), mean free path (MFP), and effective atomic number (Zeff) of the BPANZDyTb glass were studied using Phy-X software. The results of the gamma-ray parameter show that the Dy3+ ions and Tb3+ ions co-doped BoroPhosphate glass is an appropriate material for radiation shielding applications.

Reducing Effect of Hypnotherapy Anxiety in Pregnant Women

Pregnant women experience feelings of uncertainty, namely positive and negative feelings about the presence of the baby. Positive feelings are in the form of happiness that is expressed freely and do not cause feelings of guilt, and negative feelings are feelings of anxiety about the pain that will occur during childbirth. The third trimester is the peak of the emotional excitement of the birth of a baby. The third trimester is often called the waiting and alert period because at that time the mother can't wait for the birth of her baby. Sometimes mothers worry that their baby will end at any time. The aim of this research is to determine the effect of hypnotherapy on the anxiety of pregnant women at the Siatas Barita Community Health Center, North Tapanuli Regency in 2022. Research Method, This research is a Quantitative research with the research design used is Quasi Experiment with a one group pre test and post test design. A total of 40 pregnant women were taken from Siatas Barita Health Center, North Tapanuli Regency in 2022. Hajil Research. The Wilcoxon test from one group pre test and post test obtained a ρ - value of 0.01, which means that there is an effect of hypnotherapy on reducing the anxiety of pregnant women before and after treatment. The ρ value in this study is 0.01, which is smaller than 0.05, so there is an influence of hypnotherapy to reduce the anxiety of pregnant women at the Siatas Barita Health Center, North Tapanuli Regency in 2021. This shows that Ha was accepted, which means there was an influence of hypnotherapy after the intervention was carried out. Conclusion. There is an effect of hypnotherapy on reducing anxiety in pregnant women, where the Wilcoxon test results have a value of ρ = 0.00 (ρ &lt; 0.05).

The interlayer twist effectively regulates interlayer excitons in InSe/Sb van der Waals heterostructure

The interlayer twist angle endows a new degree of freedom to manipulate the spatially separated interlayer excitons in van der Waals (vdWs) heterostructures. Herein, we find that the band-edge Γ-Γ interlayer excitation directly forms interlayer exciton in InSe/Sb heterostructure, different from that of transition metal dichalcogenides (TMDs) heterostructures in two-step processes by intralayer excitation and transfer. By tuning the interlayer coupling and breathing vibrational modes associated with the Γ-Γ photoexcitation, the interlayer twist can significantly adjust the excitation peak position and lifetime of recombination. The interlayer excitation peak in InSe/Sb heterostructure can shift ~400 meV, and the interlayer exciton lifetime varies in hundreds of nanoseconds as a periodic function of the twist angle (0°–60°). This work enriches the understanding of interlayer exciton formation and facilitates the artificial excitonic engineering of vdWs heterostructures.

Synthesis of green fluorescent carbon dots using cysteine and maltose as ecofriendly ligands for the detection of venlafaxine anti-depression drug in pharmaceutical and plasma samples

In this work, the green emissive carbon dots (CDs) were fabricated using cysteine and maltose as bio-precursors via refluxing process. The emission and excitation peaks of fabricated cysteine-maltose CDs (CM-CDs) are noticed at 511 and 420 nm, respectively. The as-fabricated CM-CDs displayed average mean size of 3.63 ± 1.12 nm with uniform spherical shape and good quantum yield of 32.81 %. Importantly, the as-fabricated CM-CDs act as a sensor for venlafaxine an anti-depression drug sensing via a fluorescence “turn-off” mechanism. The fluorescence lifetime of CM-CDs was 1.34 ns. The as-fabricated CM-CDs were highly sensitive towards venlafaxine, displaying good linear range from 0.1 to 180 µM with the limit of detection of 75.15 nM. The fluorescence of CM-CDs was reduced with the interaction of venlafaxine, thereby favoring to develop CM-CDs-based cellulose paper sensor for venlafaxine assay. The fabricated sensor was effectively utilized for the quantification of venlafaxine in pharmaceutical and biological samples with good recovery rates (96.01––99.65 %).

Multiexcitation Peaks and Multicolor Emission Nanoassemblies for Transmembrane Cell Imaging and Photoresponsivity Antibacterial.

Nanomaterials with photoresponsivity have garnered attention due to their fluorescence imaging, photodynamic, and photothermal therapeutic properties. In this study, a photoresponsivity nanoassembly was developed by using photosensitizers and carbon dots (CDs). Due to their multiple excitation peaks and multicolor fluorescence emission, especially their membrane-permeating properties, these nanoassemblies can label cells with multiple colors and track cell imaging in real time. Additionally, the incorporation of photosensitizers and CDs provides the nanoassemblies with the potential for photodynamic therapy (PDT) and photothermal therapy (PTT). The nanoassemblies effectively suppressed the activity of Escherichia coli and Staphylococcus aureus through PDT and PTT. Moreover, the nanoassemblies exhibited a high affinity for E. coli and S. aureus. These distinct features confer broad-spectrum antibacterial properties to the nanoassemblies. As a photoresponsivity nanoplatform, these nanoassemblies have demonstrated potential applications in the fields of bioimaging and antimicrobial.

Data-driven prediction of rail neutral temperature for continuously welded rails using impulse-based vibration frequencies

Continuously welded rails (CWR) are prone to the development of high thermal-induced load along the axial direction. Excessive levels of load lead to risk of rail buckling and potential for derailment. Knowledge of the in situ rail axial load in CWRs is therefore important to ensure safe rail management. Field-deployable, nondestructive evaluation techniques for measuring the rail load, or a widely adopted alternative called rail neutral temperature (RNT), are desired. This study uses a data-driven approach to investigate if rail dynamic response data, collected in a non-destructive fashion, can be used to predict RNT. The study is based on a data set comprising rail equivalent strain, temperature and vibration resonance frequencies that was collected from a revenue-service rail over a period of nearly two years. All excited vibration resonance peaks are identified from other peaks caused by noise using spectral amplitude variance. Among these resonance peaks, potentially useful resonances are identified with respect to stacked spectra collected across a testing day using an assumed temperature-frequency relation. A subset of the identified useful resonances is then identified based on their consistent appearance across both testing locations and all testing days, strong correlation to effective strain, and strong correlation to each other. Three particular vibration resonances (or vibration modes -- these terms will be used interchangeably throughout this paper unless specified otherwise. The term mode does not necessarily indicate mode shapes or mode families.) emerge from this process as best candidates. A classic feature selection technique, Lasso linear regression, is then employed to identify critical power combinations of the three resonant mode frequencies. Two power combinations exhibit unique correlation to the measured equivalent axial strain at both test locations across all testing days, and thus show particular ability to predict RNT. The RNT is predicted at one test location using different models based on the power combination data from the other location, and vice versa, where the predictions satisfy standard RNT measurement accuracy expectations.

Excitation/emission-enhanced heterostructure photonic crystal array synergizing with "DD-A" FRET entropy-driven circuit for high-resolution and ultrasensitive analysis of ctDNA

Circulating tumor DNA (ctDNA) is an emerging biomarker of liquid biopsy for cancer. But it remains a challenge to achieve simple, sensitive and specific detection of ctDNA because of low abundance and single-base mutation. In this work, an excitation/emission-enhanced heterostructure photonic crystal (PC) array synergizing with entropy-driven circuit (EDC) was developed for high-resolution and ultrasensitive analysis of ctDNA. The donor donor−acceptor FÖrster resonance energy transfer ("DD-A" FRET) was integrated in EDC based on the introduction of simple auxiliary strand, which exhibited higher sensitivity than that of traditional EDC. The heterostructure PC array was constructed with the bilayer periodic nanostructures of nanospheres. Because the heterostructure PC has the adjustable dual photonic band gaps (PBGs) by changing nanosphere sizes, and the "DD-A" FRET can offer the excitation and emission peak with enough distance, it helps the successful matches between the dual PBGs of heterostructure PC and the excitation/emission peaks of "DD-A" FRET; thus, the fluorescence from EDC can be enhanced effectively from both of excitation and emission processes on heterostructure PC array. Besides, high-resolution of single-base mutation was obtained through the strict recognition of EDC. Benefiting from the specific spectrum-matched and synergetic amplification of heterostructure PC and EDC with "DD-A" FRET, the proposed array obtained ultrasensitive detection of ctDNA with LOD of 12.9 fM, and achieved the analysis of mutation frequency as low as 0.01%. Therefore, the proposed strategy has the advantages of simple operation, mild conditions (enzyme-free and isothermal), high-sensitivity, high-resolution and high-throughput analysis, showing potential in bioassay and clinical application.

Phase identification and photophysical characteristics of vanadate-based nanophosphors for lighting and latent fingerprinting applications

Monoclinic structure-based Er3+-activated Ba2BiV3O11 nanophosphors have been developed via an easy and cost-efficacious urea-aided solution combustion (SC) procedure. Various spectroscopic and structural investigations thoroughly examine the produced powders. The crystal structure has been resolved by employing a combination of X-ray diffraction (XRD) and the Rietveld refinement practice. The developed powdered nanosamples are crystallized in a monoclinic crystal system with P21/a space group. Further, to evaluate the composition of elements and their relative distribution, energy dispersive X-ray (EDAX) analysis was performed. The band gap values for the host matrix and the optimal nanophosphors were measured using a DR spectrophotometer; the obtained values were 3.47 eV and 3.40 eV, respectively. The strongest excitation peak at 381 nm is closely-matched with the characteristic wavelength of commercialized near ultraviolet (NUV) based LEDs. The characteristic emission spectra of Ba2Bi1-xErxV3O11 (x = 0.01–0.1) phosphors show the strongest emission at 553 nm (4S3/2 → 4I15/2). Additionally, photometric parameters such as quantum efficiency (86 %), color coordinates (x = 0.2568 and y = 0.4551), and correlated color temperature (CCT = 7722 K) are obtained from PL data and are strongly advised for use in wLEDs, color displays, imaging, lighting, and latent fingerprint applications.

Microwave-assisted one-pot synthesis of carbon dots from biomass: Fe(III) ion sensing and in-situ methylene blue reduction catalytic activity

In this study, zero-dimensional fluorescent carbon dots were synthesized from affordable organic bio-precursors derived from chayote seeds using a one-pot microwave-assisted carbonization process. These biomass-derived carbon dots display excellent fluorescence properties, with an average size of approximately 3.3 nm and a fluorescence quantum yield about 9.56 %. The fluorescence emission spectra were recorded at different excitation peaks, with the highest intensity emission peak observed at 387 nm with an excitation wavelength of 320 nm. These carbon dots effectively detect Fe3+ ions, with a detection limit of 4.5 µmol. Carbon dots show strong catalytic reduction activity against a reduction of Methylene Blue dye, achieving an 81 % reduction in a short period. These biomass-derived carbon dots presents sustainable and promising option for applications in metal sensing and catalytic degradation.

Riboflavin-Induced DNA Damage and Anticancer Activity in Breast Cancer Cells under Visible Light: A TD-DFT and In Vitro Study.

Targeted treatments for breast cancer that minimize harm to healthy cells are highly sought after. Our study explores the potentiality of riboflavin as a targeted anticancer compound that can be activated by light irradiation. Here, we integrated time-dependent density functional theory (TD-DFT) calculations and an in vitro study under visible light. The TD-DFT calculations revealed that the electronic charge transferred from the DNA base to riboflavin, with the most significant excitation peak occurring within the visible light range. Guided by these insights, an in vitro study was conducted on the breast cancer cell lines MCF-7 and MDA-MB-231. The results revealed substantial growth inhibition in these cell lines when exposed to riboflavin under visible light, with no such impact observed in the absence of light exposure. Interestingly, riboflavin exhibited no/minimal growth-inhibitory effects on the normal cell line L929, irrespective of light conditions. Moreover, through EtBr displacement (DNA-EtBr) and the TUNEL assay, it has been illustrated that, upon exposure to visible light, riboflavin can intercalate within DNA and induce DNA damage. In conclusion, under visible light conditions, riboflavin emerges as a promising candidate with a selective and effective potent anticancer agent against breast cancer while exerting a minimal influence on regular cellular activity.

The effects of temperament type on infusion extravasation in newborns

Infusion extravasation has an increased incidence in newborns, which can result in various adverse outcomes. This study aimed to investigate the effects of different types of temperament on infusion extravasation in newborns. A total of 209 newborns aged 4–7 days who were treated with infusion therapy were assessed for temperament type using the neonatal behavioral assessment scale score (NBAS). The 2009 Infusion Nurses Society clinical grading criteria for extravasation were used, and the clinical data of the newborns, such as gestational age and body weight, were collected. Out of 209 newborns assessed, 107 developed infusion extravasations, with an incidence rate of 51.2%. Newborns with intermediate temperament type were more prone to develop infusion extravasation. Newborns with low body weight, amniotic fluid aspiration syndrome, or meconium aspiration syndrome were prone to develop infusion extravasation. Body weight, temperament type of consolability, temperament type of peak of excitement, diseases, general temperament type, and NBAS total scores of the neonates were independent risk factors for infusion extravasation. Thus, different types of temperament can have an impact on neonatal extravasation.

Bi3+-activated Na3Ca2TaO6: A novel narrow-band blue-emitting phosphor towards backlight display applications

Developing efficient and stable narrow-band blue phosphors has always been crucial for advancing LED backlighting technology. In this study, a host of Na3Ca2TaO6 with a strong rigid structure and high cationic site symmetry was selected, while Bi3+ was utilized as the activator. A novel narrow-band blue-emitting phosphor Na3Ca2TaO6:Bi3+ was obtained through high temperature solid phase sintering. The excitation peak of Na3Ca2TaO6:0.005Bi3+ is at 370 nm, which can effectively match the near-ultraviolet chip. Under near-ultraviolet light excitation, the Na3Ca2TaO6:0.005Bi3+ sample exhibits narrow-band blue emission, characterized by a dominant peak at 421 nm and a full width at half maximum of 47 nm. Additionally, Na3Ca2TaO6:Bi3+ demonstrates the color purity of 93.7 %, a quantum efficiency of 56.3 % and thermal stability of 80 %@150 °C. Based on crystal structure data, spectral data, and empirical formulas, it can be inferred that Bi3+ occupies the Na2 and Ca site and forms two luminous centers in Na3Ca2TaO6. When Na3Ca2TaO6:Bi3+ is utilized as the blue light component in WLED devices packaging, an impressive NTSC color gamut of 89.4 % can be achieved. The present study is anticipated to serve as a valuable point of reference for the future advancement of phosphors specifically tailored for backlight display applications.

Synchronous Fluorescence as a Sensor of Trace Amounts of Polycyclic Aromatic Hydrocarbons.

Synchronous fluorescence spectroscopy (SFS) is a technique that involves the simultaneous detection of fluorescence excitation and emission at a constant wavelength difference. The spectrum yields bands that are narrower and less complex than the original excitation and emission bands. The SFS bands correspond uniquely to the fluorescing molecule. Our investigation focuses on evaluating the sensitivity of the SFS technique for the detection and quantitation of PAHs relevant to astrochemistry. Results are presented for naphthalene, anthracene, and pyrene in three different solvents: n-hexane, water, and ethanol. SF bands are obtained with a constant wavelength difference between the peak excitation and emission wavelength (Δλ = λex - λem) at a concentration ranging from 10-4 to 10-10 M. Limit of detection (LOD) and limit of quantitation (LOQ) calculations are based on integrated SF band areas at different concentrations. Spectra of 23 pg/g of anthracene, 16 pg/g, and 2.6 pg/g of pyrene are recorded using ethanol as the solvent. The PAHs exhibit detection limits in the fractions of parts-per-billion (ng/g) range. Through comparison with similar prior studies employing fluorescence emission, our findings reveal a better detectability limit, demonstrating the effectiveness and applicability of the SFS technique.

Synthesis and characterization of polyurethane-based self-luminous pavement coatings: a performance evaluation study

Improving the nighttime vision of drivers is essential, given the growing advancements in urban transportation. In this study, polyurethane-based self-luminous pavement coatings (PSCs) were prepared by doping luminous powders (LPs) into the polyurethane materials. The superior optical properties and chemical stabilities of these coatings were ensured by synthesizing the polyurethane-based material. Then, the PSCs were evaluated for their comprehensive performances, such as luminescence, aging resistance, and abrasion resistance, using various characterization methods, including fluorescence spectral analysis, Fourier-transform infrared spectroscopy, fluorescence microscopy, and mechanical property testing. The results show that the 50-mesh LP has the optimal overall performance, with an initial luminescence that exceeds those of the 100 and 400 meshes. The initial brightness of the PSC is mainly influenced by the LP and increases with dosage. The lattice structure and luminescent properties of the luminescent material did not change after coating preparation. The peak excitation wavelength of 420 nm implies that the coating has the best excitation effect under UV light. The primer-marking coating effectively improves the abrasion resistance of the PSC, and the mass loss of the PSC with a coating thickness of 0.4 kg/m2 is 52.9% of that without the primer-marking coating, with the optimal coating thickness being 0.6 kg/m2. This research provides an innovative solution to improve nighttime roadway lighting, which provides useful support for the sustainable development of urban transportation infrastructures and construction of intelligent transportation systems.