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A novel two‐parameter sensor is proposed based on the abrupt taper and micro‐arc Michelson interferometer (MI) in single‐mode fiber. When there is a regular change in the liquid level or temperature, the phase difference changes, and the spectral intensity or wavelength of the interfering valleys of this sensor is directionally shifted. This study enriches the construction of MI and provides a new perspective on liquid level measurement. We experimentally explored the sensor's sensing performance over temperature and liquid level: this sensor's temperature sensitivity and liquid level sensitivity were up to 62.9 pm/°C and 0.2896 dB/mm, respectively. In addition, this sensor is characterized by compactness, simplicity, low cost, and high reliability, and it is suitable for measurement of liquid level and temperature, expanding the application field of MI. [ABSTRACT FROM AUTHOR]

The aim of the work was to study the influence of biogenic metal nanoparticles on the growth characteristics and biosynthetic activity of the fungus Laricifomes officinalis, as well as the effects of photocatalytic activity of NPs after exposure to low-intensity laser radiation under deep cultivation conditions. Material and Methods. Traditional mycological methods, colloidal solutions of nanoparticles biogenic metals, and unique photobiological methods were used. The effect of light on the biosynthetic acti vity of L. officinalis was studied using low-intensity coherent monochromatic laser light with specified spectral and intensity characteristics. The experiment used water-based colloidal solutions of biogenic metals such as Fe, Mg and Ag, obtained by a patented method. Results. Treatment of the inoculum with colloidal solutions of nanoparticles of all used metals increased the growth of L. officinalis by 31–54%, while irradiation of the fungal inoculum with laser light in a medium with nanoparticles reduced the growth activity of the L. officinalis mycelium by 14.4– 22.6%. All nanoparticles suppressed the biosynthesis of extracellular polysaccharides, whereas treatment of the inoculum with colloidal solutions of FeNPs and MgNPs stimulated the synthesis of endopolysaccharides. At the same time, laser light irradiation in the presence of AgNPs increased the amount of endopolysaccharides, while FeNPs and MgNPs slightly inhibited their synthesis. Treatment of the inoculum with colloidal metal solutions and laser light affected the total phenolic content (TPC) in the mycelial mass. The highest TPC values in ethanol extracts with AgNPs and laser light irradiation were 97.31±3.7 mg of GAEs/g of dry mass. Conclusions. The research results gave ground to consider nanoparticles of biogenic metals (AgNPs, FeNPs, MgNPs) and low-intensity laser light as a promising regulators of the biosynthetic activity of L. officinalis in the biotechnology of its cultivation. [ABSTRACT FROM AUTHOR]

Serum contains rich elemental information, and the elemental analysis of the serum using laser-induced breakdown spectroscopy (LIBS) can help with the diagnosis and treatment of cancer. In this work, serum specimens from breast cancer patients were used as samples, and the elements Mg, Ca, and K were analyzed using LIBS. Silver nanoparticles (Ag NPs) were introduced to enhance spectral emission intensities, and this technique is known as nanoparticle-enhanced LIBS (NELIBS). An Ag NP-coated filter paper (Ag NP paper) substrate was prepared and was compared with silicon and aluminum substrates for NELIBS analysis. The Ag NP paper substrate showed lower spectral intensity variances and better elemental distribution uniformity due to the reduced coffee-ring effect compared with silicon and aluminum substrates. The enhanced effect of the Ag NP paper was optimized by adjusting serum volume and Ag NPs concentration. It was found that Mg, Ca, and K required different optimal conditions for spectral enhancement. The highest enhancement factors (EF) for Mg, Ca, and K were 1.85, 1.76, and 3.10, respectively. The electron temperature (Te) and electron number density (Ne) of NELIBS plasmas were measured using the Boltzmann plot and Stark broadening methods and compared with those of the normal LIBS plasmas. The Te and Ne of the NELIBS and normal LIBS samples were generally comparable with each other. Higher Ag NP concentrations led to lower Te values for NELIBS plasmas. [ABSTRACT FROM AUTHOR]

Shadows in hyperspectral images lead to reduced spectral intensity and changes in spectral characteristics, significantly hindering analysis and applications. However, current shadow compensation methods face the issue of nonlinear attenuation at different wavelengths and unnatural transitions at the shadow boundary. To address these challenges, we propose a two-stage shadow compensation method based on multi-exposure fusion and edge fusion. Initially, shadow regions are identified through color space conversion and an adaptive threshold. The first stage utilizes multi-exposure, generating a series of exposure images through adaptive exposure coefficients that reflect spatial shadow intensity variations. Fusion weights for exposure images are determined based on exposure, contrast, and spectral variance. Then, the exposure sequence and fusion weights are constructed as Laplacian pyramids and Gaussian pyramids, respectively, to obtain a weighted fused exposure sequence. In the second stage, the previously identified shadow regions are smoothly reintegrated into the original image using edge fusion based on the p-Laplacian operator. To further validate the effectiveness and spectral fidelity of our method, we introduce a new hyperspectral image dataset. Experimental results on the public dataset and proposed dataset demonstrate that our method surpasses other mainstream shadow compensation methods. [ABSTRACT FROM AUTHOR]

In this article, over three thousand meteor spectra recorded in Saitama, Japan, between 2018 and 2021 are analysed. We performed a principal component analysis of the intensity of the sodium and magnesium lines and the iron band of each meteor in combination with the orbital elements and the kinematic parameters such as the geocentric velocity and the initial and final altitudes to determine the relative importance of each of these variables in the composition of a meteor's spectrum. We found that for meteor showers such as GEM, LEO, QUA, and PER, the orbital elements or kinematic parameters are important parameters that determine the intensity of these spectral lines, which could indicate the influence of gravitational and/or non-gravitational forces in distinguishing the composition or variations in the strength of the meteoroid material in each meteor shower. The normal spectral type in our sample ranges from 39.5 per cent to 96.8 per cent, corresponding to GEM and PER, respectively. The COM meteors have a similar sodium content to the components of the LEO and PER showers, suggesting a comet as a possible parent body. The sodium and magnesium content of the iron-class meteoroids is the lowest of all our samples, but it is not zero, suggesting that there are no pure iron meteoroids. The sodium content of the GEM meteor shower shows temporal variations in 2021 compared to the 2019 and 2020 observing seasons. We found no correlation between the sodium content and the perihelion distance for other meteor showers. [ABSTRACT FROM AUTHOR]

Phosphor‐converted near‐infrared (NIR) LEDs are becoming increasingly demanded as miniature, portability, and broad emission spectrum. In this work, a class of Fe3+‐activated double perovskite structured is reported ALaBB′O6 (A = Ba, Sr, Ca; B–B′ = Li–Te, Mg–Sb) phosphors. Through the co‐substitution strategy at the A‐site and B‐B' sites, the emission spectral intensity and position of Fe3+ ions can be tuned. Finally, by utilizing Ca2+ at the A‐site and Mg–Sb co‐substitution for Li–Te, long‐wave NIR emission centered at 995 nm in CaLaMgSbO6: 0.6%Fe3+ with a full width at half maximum of 147 nm and internal quantum efficiency of 54.05% is achieved. The effects of the double perovskite crystal structure on Fe3+ photoluminescence properties are comprehensively analyzed. NIR LEDs are fabricated by encapsulating UV chips with the synthetic CaLaMgSbO6: 0.6%Fe3+ phosphors, and their application value in night vision, nondestructive biological monitoring, and NIR detection is evaluated. [ABSTRACT FROM AUTHOR]

When laser-induced breakdown spectroscopy (LIBS) was used in online equivalence ratio measurements, the spatial–temporal temperature gradient would lead to significantly varied baselines, which require real-time corrections. In this study, the correlation relationship between spectral intensity and broadband radiation was utilized as the physical constraint in automatic baseline correction. The pixel-to-pixel correlation coefficient on the wavelength ( R 2 ) was introduced as the "Correlation Spectrum", and the summation of all correlation coefficients ( s u m R 2 ) was used as an objective function. By maximizing s u m R 2 using Particle Swarm Optimization algorithm, the key parameters in the adaptive iteratively reweighted Penalized Least Squares (airPLS) method were automatically optimized. The baselines fitted by airPLS could adapt to the plasma excitation variations in a temperature range from 1458 to 1705 K, which improved accuracy in equivalence ratio measurements. The potential advantages of Correlation Spectrum in weak peak identification and broadening effect evaluation were also demonstrated. The benchmarked results suggested that the proposed approach can be conveniently employed in online LIBS measurements and improve its quantification performance. [ABSTRACT FROM AUTHOR]

Due to their excellent thermal conductivity and sensitivity to temperature changes, special attention should be paid to the influence of temperature on steel-structure bridges. The temperature effect is complex, especially for unstable steel arch bridges with complex structural forms. This paper proposes an approximate method that measures the three-dimensional temperature field of the symmetrical arch rib with the two-dimensional temperature field of multiple sections. In addition, it converts the complex radiant intensity calculation of the special-shaped steel box arch rib into the calculation of numerous planar radiant intensities. It uses the ANSYS Workbench to establish the three-dimensional transient thermal analysis finite element model of the No. 2 steel box arch rib. The influence of seasons and arch rib direction on the temperature field of steel box arch ribs and the stress and deformation of steel box arch ribs under non-linear temperature effects were analyzed. The results show that the temperature changes in different seasons significantly impact the temperature changes in the arch ribs. The change in the azimuth angle of the arch rib has a significant impact on the temperature difference between the web plates on both sides of the arch rib; under the influence of the temperature field at the most unfavorable time in summer and winter, symmetrical stress concentration occurs in the arch foot area. Furthermore, the maximum vertical displacement is 13.9 mm and 10.8 mm, respectively. Finally, when the angle is 40°, the maximum temperature difference between the web plates on both sides is 6.9 °C. [ABSTRACT FROM AUTHOR]

Extreme wave events or rogue waves (RWs) are both statistically rare and of exceptionally large amplitude. They are observed in many complex systems ranging from oceanic and optical environments to financial models and Bose–Einstein condensates. As they appear from nowhere and disappear without a trace, their emergence is unpredictable and non‐repetitive, which makes them particularly challenging to control. Here, the use of genetic algorithms (GAs), which are exclusively designed for searching and optimizing stationary or repetitive processes in nonlinear optical systems, is extended to the active control of extreme events in a fiber laser cavity. Feeding real‐time spectral measurements into a GA controlling the electronics to optimize the cavity parameters, the wave events are able to be triggered in the cavity that have the typical statistics of RWs in the frequency domain. The intensity of the induced RWs can also be tailored. This accurate control enables the generation of optical RWs with a spectral peak intensity 32.8 times higher than the significant intensity threshold. A rationale is proposed and confirmed by numerical simulations of the laser model for the related frequency up‐ and downshifting of the optical spectrum that are experimentally observed. [ABSTRACT FROM AUTHOR]

Femtosecond pulsed lasers are widely used in applied technologies, such as laser processing, nonlinear optical microscopy, and time-of-flight measurement, wherein narrowing the pulse duration is particularly important for improving the processing efficiency and signal-to-noise ratio of measurement systems. This paper proposes a method for shortening temporal pulse waveforms using spectral intensity filtering. Symmetrical spectral filtering was specifically applied at the central wavelength of the femtosecond pulsed laser spectrum. To investigate the pulse-narrowing effect, we numerically simulated the pulse duration as a function of the filtering width and cut-off wavelength position. The results of these simulations showed that the pulse duration decreased as the filter wavelength approached the central wavelength of the light. Furthermore, increasing the filter width reduced the pulse duration. Additionally, we implemented a spatial light modulator-based pulse-shaping system to realize a spectral intensity filter. We experimentally demonstrated that the duration of a telecom-band pulse was reduced by 9.8% when using a spectral intensity filter with a width of 1 nm. [ABSTRACT FROM AUTHOR]

The development of sophisticated solar-blind photodetector devices is being motivated by the increasing need for solar-blind sensors with remarkable photosensitive qualities. This work is a modeling and simulation of electrical and optical properties of a Schottky photodetector based on gallium oxide (Ga2O3), one of the most promising wide-band-gap material. It focuses on the optimization of the device structure design, assumed fully transparent to visible light. In addition, analysis of electrical and optical properties of β-Ga2O3-based photodetector was carried out to accurately describe physical phenomenon through the semiconductor bulk. The impact of several parameters of the device on its performances is such as layer thickness, doping concentration, and electron affinity, anode work function and different cathode contact materials. Besides that, and for more understanding the real behaviors within different layers of the photodetector, diverse optical parameters were varied, for instance the light power intensity and the spectral response by changing the optical wavelength. The obtained results show a promising performance enhancement compared to previous works, for instance the photo to dark current ratio of 3 × 104, the good spectral responsivity in UV light illumination [250–350 nm], in addition to the relatively high detectivity of 2.5 × 109 (Jones). [ABSTRACT FROM AUTHOR]

The solar ultraviolet intensities of spectral lines originating from Li- and Na-like ions have been observed to surpass the expectations derived from plasmas with coronal approximation. The violation of the coronal approximation can be partially attributed to nonequilibrium ionization (NEI) due to dynamic processes occurring in the vicinity of the transition region. To investigate the impact of these dynamics in the Alfvén wave-heated coronal loop, a set of equations governing NEI for multiple ion species was solved numerically in conjunction with 1.5-dimensional magnetohydrodynamic equations. Following the injection of Alfvén waves from the photosphere, the system undergoes a time evolution characterized by phases of evaporation, condensation, and quasi-steady states. During the evaporation phase, the ionization fractions of Li- and Na-like ions were observed to increase when compared to the fractions in ionization equilibrium, which led to an enhancement in the intensity of up to 1.6. This over-fractionation of Li- and Na-like ions was found to be induced by the evaporation process. While collisions between shocks and the transition region temporarily led to deviations from ionization equilibrium, on average over time, these deviations were negligible. Conversely, under-fractions of the ionization fraction led to a reduction in intensity down to 0.9 during the condensation phase and the quasi-steady state. Given the dependency of the over/under-fractionation on mass circulations between the chromosphere and the corona, these observations will serve as valuable benchmarks to validate not only Alfvén wave models but also other existing mechanisms on coronal heating. [ABSTRACT FROM AUTHOR]

The distribution of microscopic particles directly affects the recovery of the post arc insulating medium and determines whether the fault current can be interrupted. Based on the principle of vacuum arc emission spectrum, a high-speed spectrum observation platform was built to study the distribution of microscopic particles during the arc burning, and the axial and radial spectral line intensity and density distributions of atoms and ions under different current amplitudes were obtained. The results show that the CuI spectral line intensity has two peaks near the cathode and anode, while in the arc column it is relatively low. The peak of the CuI spectral line intensity near the electrode is caused by electrode evaporation. The peak duration of the CuI spectral line intensity near the cathode is always longer than that near the anode. The CuII spectral line intensity is lower, appears later and disappears earlier, which in the arc column increased obviously, compared with CuI. The CuII density near the cathode is higher than that near the anode, and the CuII density in the arc column is higher than in the two electrodes, which is similar to the axial distribution of electron density. The radial distribution curve of CuI and CuII density is similar to the radial distribution curve of spectral line intensity, and displays the characteristics of a high center and low edge in the radial direction of the arc gap. The difference is that the width of the atomic spectral line is larger than that of the corresponding ionic spectral line, the distribution curve of the ionic spectral line is smooth and symmetrical, and the radial attenuation rate of the CuII density is larger than that of the corresponding CuI. This reflects the ionization of atoms and the effect of magnetic fields. The radial and axial distribution of the particle density is opposite to that of the excitation temperature. Electrode emission will first affect the atom formation. [ABSTRACT FROM AUTHOR]

The monitoring of additive manufacturing processes such as powder bed fusion enables the detection of several process quantities important to the quality of the built part. In this context, radiation-based monitoring techniques have been used to obtain information about the melt pool and the general temperature distribution on the surface of the powder bed. High temporal and spatial resolution have been achieved at the cost of large storage requirements. This contribution aims to offer an alternative strategy of gaining information about the powder bed's temperature field with sufficient resolution but with an economical amount of data. The investigated measurement setup uses a spectrometer to detect the spectral radiation intensities emitted by an area enclosing the melt pool and part of its surroundings. An analytical description of this process is presented, which shows that the measured spectral entities can be reconstructed by the Ritz method. It is also shown that the corresponding weighting factors can be physically interpreted as subdomains of constant temperature within the measurement area. Two different test cases are numerically analyzed, showing that the methodology allows for an approximation of the melt pool size while further assumptions remain necessary to reconstruct the actual temperature distribution. [ABSTRACT FROM AUTHOR]

In recent years, much effort has been devoted to understanding the response of plants to different light properties, largely due to advances in the light-emitting diode (LED) industry. This work studied the effect of different light intensities and qualities on yield or quality of indoor hydroponic spinach (Spinacia oleracea L.). Two trials were carried out at two different times. The intensity assay was carried out with the same type of light (AP673L, Valoya Ltd., Helsinki, Finland) at different luminous intensities (150, 290, and 430 µmol m−2 s−1). In the second trial, four different luminance spectra (Valoya Ltd., Helsinki, Finland) were used (NS12, AP67, AP673L, G2). Then, the fresh and dry weight, nutritional status, and concentration of primary metabolites were determined. Both lights parameters induced changes in vegetative performance and other physiological traits, as well as their quality and nutritional composition (minerals, organic acids, sugars, and amino acids). The increase in light intensity increased Fv'/Fv', fresh weight, leaf area, chlorophyll fluorescence parameters, and potassium concentration. The light intensity effectively controlled nitrate accumulation in an inverse relationship. The effect of the light spectrum on spinach characteristics was not clearly observed when multivariate statistics were applied to the data. No linear relationship was found between the different R/B ratios. This is perhaps due to commercial lights having a complex combination of wavelengths, in addition to the main R/B proportion. Within the overall results, 6 R/B presented the best results for the indoor cultivation of spinach. More studies are needed, since breeding for controlled environments shifts the focus of the desired crop attributes towards rapid growth and harvest quality instead of stress adaptability. [ABSTRACT FROM AUTHOR]

This paper introduced electrostatic-assisted laser-induced breakdown spectroscopy (LIBS) to enhance spectral intensity and improve the quantitative accuracy of trace metal elements (Cu, Al, Zn, Ca and Na) in aqueous solutions. Firstly, the effect of the voltage and pole-plate distance of the electrostatic field on the spectral intensity was investigated. The spectral intensity of metal elements was enhanced by changing DC voltage and the plate distance. Secondly, the effect of electrostatic-assisted LIBS on the quantitative analysis was investigated, and the limits of detection (LOD) and quantification (LOQ) were calculated with and without electrostatic-assisted LIBS. The use of electrostatic-assisted LIBS reduced the LOD and LOQ of metal elements by an order of magnitude, respectively. Finally, several regression analysis models including least squares regression analysis (PLSR), support vector machine regression analysis (SVR), backpropagation neural network regression analysis (BP-ANN), whale optimization algorithm-SVR (WOA-SVR), and whale optimization algorithm-BP (WOA-BP) were established to predict the concentration regression based on the collected spectral information. Compared to the traditional regression methods, the improved machine-learning algorithms based on intelligent optimization algorithms achieved the highest regression prediction accuracy of 99.81%. These findings confirm the capability and accuracy of electrostatic-assisted LIBS combined with machine-learning algorithms for detecting trace metal elements in aqueous solutions. [ABSTRACT FROM AUTHOR]

Based on the generalized Huygens-Fresnel principle, an analytical expression for the spectral intensity of the radial array Gaussian Schell mode beam (RAGSM) in inhomogeneous atmospheric turbulence is derived using the theory of partially coherent light. The variation of the normalized spectral intensity and the on-axis relative spectral shift are investigated. The effects of beam parameters and turbulent parameters on the spectra are numerically calculated. The results show that there is a critical position where a rapid transition of the spectrum takes place. The critical position becomes greater with an increase in the number of sub-beams, the radial distance, initial coherence length. At the longer propagation distance, the effect of structural constants of refractive index is weaker. The spectral transition distances are proportional to the turbulence parameters. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate that β-Ga2O3 shows orientation-dependent polarized photoluminescence (PL) emission and give a comprehensive insight into gallium oxide's PL spectral properties. We characterized the polarization and spectral dependencies of both the incident and emitted light for (−201) unintentionally doped (UID) as well as (−201) and (010) Sn-doped and Fe-doped crystals. We observed for UID and Sn-doped samples that the electron to self-trapped hole and native defect-related emission bands are linearly polarized with polarized emission intensities ordered as E || c (and c*) > E || a (and a*) > E || b. Furthermore, the spectral shape of emission does not change between the UID and Sn-doped samples; instead, the Sn-doping quenches the total PL spectral intensity. For Fe-doped samples, polarized red emission caused by unintentional Cr3+ doping generates emission intensities ordered E || b > E || c (and c*) > E || a (and a*). It is also observed that in some circumstances, for some doped crystals, the PL spectra can show variations not only in intensity but also in spectral shape along different polarization directions. As an example, the PL emission band for emission along c is blueshifted relative to that along a in Sn-doped β-Ga2O3. [ABSTRACT FROM AUTHOR]

Aluminum trihydride (AlH3) has gained considerable attention as a substitute fuel for aluminum in solid propellants. In this study, we conducted a systematic investigation to evaluate the effects of AlH3 content, ranging from 0 % to 18 %, on propellant ignition, combustion, and agglomeration. Experimental methods such as thermogravimetry−differential scanning calorimetry (TG‐DSC), laser ignition, high‐speed photography, and collecting condensed combustion products (CCPs) were employed. The results indicate that AlH3 significantly promotes the high‐temperature decomposition of ammonium perchlorate (AP). Meanwhile, the addition of cyclotetramethylene tetranitramine (HMX) in propellant does not affect the hydrogen release reaction of AlH3. As the AlH3 content increases from 0 % to 18 %, the spectral emission intensity of the propellants decreases, and the ignition delay time initially increases from 253 ms to 321 ms, and then decreases to 258 ms. Furthermore, the burning rate increases with increasing the AlH3 content, while the pressure exponent is reduced from 0.551 to 0.460. The inclusion of AlH3 in propellants significantly inhibits aluminum agglomeration near the burning surface. Additionally, as the AlH3 content increases, the mean particle size D43 of the CCPs decreases from 50.95 μm to 8.28 μm at 1 MPa. The agglomeration degree of aluminum is very weak at 7 MPa, especially when the AlH3 content exceeds 9 %. The conclusions drawn from this study can serve as valuable guidance for optimizing propellant formulations. [ABSTRACT FROM AUTHOR]

In this paper, we perform the exact diagonalization of a light–matter strongly coupled system taking into account arbitrary losses via both energy dissipation in the optically active material and photon escape out of the resonator. This allows us to naturally treat the cases of couplings with structured reservoirs, which can strongly impact the polaritonic response via frequency-dependent losses or discrete-to-continuum strong coupling. We discuss the emergent gauge freedom of the resulting theory and provide analytical expressions for all the gauge-invariant observables in both the Power–Zienau–Woolley and the Coulomb representations. In order to exemplify the results, the theory is finally specialized to two specific cases. In the first one, both light and matter resonances are characterized by Lorentzian linewidths, and in the second one, a fixed absorption band is also present. The analytical expressions derived in this paper can be used to predict, fit, and interpret results from polaritonic experiments with arbitrary values of the light–matter coupling and with losses of arbitrary intensity and spectral shape in both the light and matter channels. A Matlab code implementing our results is provided. [ABSTRACT FROM AUTHOR]

A sparse linear algebra based implementation of Rayleigh–Schrödinger vibrational perturbation theory is presented. This implementation allows for flexibility in the coordinates used to expand the vibrational Hamiltonian as well as the order to which the perturbation theory is performed. It also provides a powerful tool for investigating the origin of spectral intensity and transition frequencies. Specifically, this flexibility allows for the analysis of which terms in the expansions of the Hamiltonian and dipole surface lead to the largest corrections to the energies and transition intensities, and how these conclusions depend on the coordinates used for these expansions. Comparisons of corrections to transition frequencies are reported for the Morse oscillator when the potential is expanded in Δr and Morse coordinates as well as for water, water dimer, and peroxynitrous acid when the molecular Hamiltonians and dipole surfaces are expanded in Cartesian displacement coordinates and in the displacements of the bond-angle-dihedral internal coordinates. Further comparisons of the corrections to the transitions moments are made for H2O and ( H 2 O) 2 . It is found that while the transition frequencies and intensities are independent of coordinate choice, a good choice of coordinates leads to a cleaner interpretation of the origins of the anharmonicities in these systems. [ABSTRACT FROM AUTHOR]

The MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) is one of the MeerKAT large survey projects, designed to pathfind SKA key science. MIGHTEE is undertaking deep radio imaging of four well-observed fields (COSMOS, XMM -LSS, ELAIS S1, and CDFS) totaling 20 square degrees to μJy sensitivities. Broad-band imaging observations between 880 and1690 MHz yield total intensity continuum, spectro-polarimetry, and atomic hydrogen spectral imaging. Early science data from MIGHTEE are being released from initial observations of COSMOS and XMM –LSS. This paper describes the spectro-polarimetric observations, the polarization data processing of the MIGHTEE early science fields, and presents polarization data images and catalogues. The catalogues include radio spectral index, redshift information, and Faraday rotation measure synthesis results for 13 267 total intensity radio sources down to a polarized intensity detection limit of ∼20 μJy bm−1. Polarized signals were detected from 324 sources. For the polarized detections, we include a catalogue of Faraday Depth from both Faraday Synthesis and Q, U fitting, as well as total intensity and polarization spectral indices. The distribution of redshift of the total radio sources and detected polarized sources are the same, with median redshifts of 0.86 and 0.82, respectively. Depolarization of the emission at longer-wavelengths is seen to increase with decreasing total-intensity spectral index, implying that depolarization is intrinsic to the radio sources. No evidence is seen for a redshift dependence of the variance of Faraday depth. [ABSTRACT FROM AUTHOR]

By focusing our attention on nitrogen components in plants, which are important for cultivation management in data-driven agriculture, we developed a simple, rapid, non-chemical and simultaneous quantification method for proteinic and nitrate nitrogen in a leaf model based on near-infrared (NIR) spectroscopic information obtained using a compact Fourier Transform NIR (FT-NIR) spectrometer. The NIR spectra of wet leaf models impregnated with a protein–nitric acid mixed solution and a dry leaf model obtained by drying filter paper were acquired. For spectral acquisition, a compact MEMS (Micro Electro Mechanical Systems) FT-NIR spectrometer equipped with a diffuse reflectance probe accessory was used. Partial least square regression analysis was performed using the spectral information of the extracted absorption bands based on the determination coefficients between the spectral absorption intensities and the contents of the two-dimensional spectral analysis between NIR and mid-infrared spectral information. Proteinic nitrogen content in the dry leaf model was well predicted using the MEMS FT-NIR spectroscopic method. Additionally, nitrate nitrogen in the dry leaf model was also determined by the provided method, but the necessity of adding the data for a wider range of nitric acid concentrations was experimentally indicated for the prediction of nitrate nitrogen content in the wet leaf model. Consequently, these results experimentally suggest the possibility of the application of the compact MEMS FT-NIR for obtaining the bioinformation of crops at agricultural on-sites. [ABSTRACT FROM AUTHOR]

This paper presents a compact source of soft X-ray radiation for operation in the wavelength range of 2–5 nm with a pulse repetition frequency of more than 500 Hz. The source parameters were optimized to reduce the intensity of ablation of the discharge volume wall and obtain the maximum intensity of the spectral lines of multicharged ions CV—4 nm and Ar IX—4.87 nm. The obtained results can be used in the development of a microscope for the tasks of cell transmission microscopy with nanometer resolution. [ABSTRACT FROM AUTHOR]

Space infrared dim target recognition is an important applications of space situational awareness (SSA). Due to the weak observability and lack of geometric texture of the target, it may be unreliable to rely only on grayscale features for recognition. In this paper, an intelligent information decision-level fusion method for target recognition which takes full advantage of the ensemble classifier and Dempster–Shafer (DS) theory is proposed. To deal with the problem that DS produces counterintuitive results when evidence conflicts, a contraction–expansion function is introduced to modify the body of evidence to mitigate conflicts between pieces of evidence. In this method, preprocessing and feature extraction are first performed on the multi-frame dual-band infrared images to obtain the features of the target, which include long-wave radiant intensity, medium–long-wave radiant intensity, temperature, emissivity–area product, micromotion period, and velocity. Then, the radiation intensities are fed to the random convolutional kernel transform (ROCKET) architecture for recognition. For the micromotion period feature, a support vector machine (SVM) classifier is used, and the remaining categories of the features are input into the long short-term memory network (LSTM) for recognition, respectively. The posterior probabilities corresponding to each category, which are the result outputs of each classifier, are constructed using the basic probability assignment (BPA) function of the DS. Finally, the discrimination of the space target category is implemented according to improved DS fusion rules and decision rules. Continuous multi-frame infrared images of six flight scenes are used to evaluate the effectiveness of the proposed method. The experimental results indicate that the recognition accuracy of the proposed method in this paper can reach 93% under the strong noise level (signal-to-noise ratio is 5). Its performance outperforms single-feature recognition and other benchmark algorithms based on DS theory, which demonstrates that the proposed method can effectively enhance the recognition accuracy of space infrared dim targets. [ABSTRACT FROM AUTHOR]

The effect of chemically active fluorine-containing additives AlF3, AgF, and ZnF2 on the nature of the evaporation of non-volatile elements, B, Be, Cr, Hf, Mo, Si, Ti, and V from aluminum oxide in a direct current arc is studied. It is found that, in the presence of these additives, the intensity of the spectral lines significantly increases and the time of complete evaporation from the electrode decreases for all elements under study, which indicates the formation of their highly volatile fluorides in the electrode crater. It is shown that zinc fluoride is the most effective additive among the studied compounds. This additive ensures the reduction of the limits of determination of highly volatile elements in aluminum oxide by one and a half to two orders of magnitude compared to the version without additives, and also the improvement of the convergence of determination results. [ABSTRACT FROM AUTHOR]

The ability of laser pulse was tested for controlled ablation of the copper alloy (CuCrZr) and nanometer-thick impurity layer on the rear surface of a glass window. The target surface was moved across the focus point (FP) to vary the distance from the FP within the depth-of-focus (DOF) of the focusing lens. An Nd:YAG laser was used at its fundamental wavelength of 1064 nm in this experiment. The controlled ablation was performed to remove the impurity from the rear surface of a glass window that was taken from the H-port of the EAST tokamak. The morphology of the laser-produced craters was measured using the 3D laser scanning confocal microscope and scanning electron microscope. The depth and diameter of the craters varied according to the laser energy which focused on the unit area. The spectral intensity increases as the distance from the FP decreases. The threshold fluence values for ablation, ignition of the plasma, and spectral emission were investigated. The laser pulse energy focused before and after the FP resulted in different ablation behaviors, crater morphologies, and spectral intensity. The precise removal of impurities from the rear surface was performed at − 2 mm from the FP. The laser ablation with variable fluence can further improve the selective ablation of impurity deposition to investigate the surface of the plasma-facing components. [ABSTRACT FROM AUTHOR]

Negative thermal quenching (NTQ) denotes that the integral emission spectral intensity of a given phosphor increases continuously with increasing temperature up to a certain elevated temperature. NTQ has been the subject of intensive investigations in recent years, and a large number of phosphors are reported to have exhibited NTQ. In this paper, a collection of results in the archival literature about NTQ of specific phosphors is discussed from a macroscopic viewpoint, focusing on the following three aspects: (1) Could the NTQ of a given phosphor be reproducible? (2) Could the associated data for a given phosphor exhibiting NTQ be in line with the law of the conservation of energy? (3) Could the NTQ of a given phosphor be demonstrated in a prototype WLED device? By analyzing typical cases based on common sense, we hope to increase awareness of the issues with papers reporting the NTQ of specific phosphors based on spectral intensity, along with the importance of maintaining stable and consistent measurement conditions in temperature-dependent spectral intensity measurement, which is a prerequisite for the validity of the measurement results. [ABSTRACT FROM AUTHOR]

This study investigates the propagation of a pulsed Laguerre higher-order cosh-Gaussian beam in turbulent maritime environments. Using the extended Huygens-Fresnel principle and the Fourier Transform method, we derive the formula for beam propagation in a marine environment. The analysis includes the influence of maritime turbulence, transverse positions, and initial beam parameters on the spectral intensity of the propagated beam. Graphical representations illustrate these effects, and numerical calculations demonstrate the relative spectral shift at various radial coordinates. The findings reveal dependencies on the refractive index structure constant, pulse duration, and beam order. Notably, on-axis spectral intensity experiences a blue shift, while off-axis spectral intensity undergoes a red shift with increasing radial coordinate. The study also highlights specific cases of the considered beam, providing valuable insights for information coding and transmission applications. [ABSTRACT FROM AUTHOR]

This study used a visualized explosion propagation experimental system to investigate the flame propagation and hydroxyl (OH·) spectral radiation characteristics of hydrogen deflagration at the hydrogen concentration range of 7–17 vol%. The experimental results indicated that maximum flame propagation velocity, maximum explosion pressure, maximum flame temperature, and maximum relative spectral intensity of OH· gradually increased with hydrogen concentration. When concentration increased from 13 vol% to 17 vol%, the time to reach the maximum flame propagation velocity, the formation time of tulip flame, and the duration of the spectral radiation signal of OH· decreased by 52.9%, 55.6%, and 48.2%, respectively. In addition, flame propagation velocity oscillated when the tulip flame appeared, and maximum explosion pressure appeared later than the maximum temperature. Maximum flame propagation velocity, maximum explosion pressure, and maximum flame temperature positively correlated with maximum relative spectral intensity in the reaction system. These findings may serve as an essential reference for the safe and effective use of hydrogen and the research and development of radical targeted explosion suppressants. • Flame propagation velocity oscillates when tulip flame appears. • Maximum spectral intensity is exponentially related to hydrogen concentration. • The OH· content positively correlate with the maximum explosion pressure. • Maximum explosion pressure appears later than maximum temperature. [ABSTRACT FROM AUTHOR]

Taking the megacity of Beijing as an example, a short‐time Fourier transform (STFT) method was employed to extract the multi‐timescale evolution pattern of the canopy urban heat island intensity (CUHII) during 2000–2020. The STFT of CUHII showed a close relationship between the evolution of the CUHII in Beijing and the background meteorological forcing at intra‐annual, weather and intra‐daily scales. The intra‐annual‐scale spectrum of CUHII exhibited an increasing trend with obvious seasonal variation of the canopy urban heat island (CUHI). The intra‐daily‐scale spectrum of CUHII showed an increasing trend with the nighttime CUHI developing faster. Increasing Western Pacific Subtropical High intensity can enhance the seasonal and diurnal fluctuations of CUHII. The weather‐scale spectrum of CUHII is controlled by weather system evolution, showing that the frequency of cold/heat waves (CWs/HWs) in Beijing was significantly negatively correlated with the weather‐scale spectral intensity of the CUHII. CWs and HWs can increase the CUHII for a long duration. Plain Language Summary: The canopy urban heat island (CUHI) phenomenon can affect human health and the ecological environment, and its multi‐timescale variability brings great uncertainty to the study of urban climates worldwide. In this study, taking the megacity of Beijing as an example, a novel short‐time Fourier transform (STFT) method was used to extract the multi‐timescale pattern of the CUHI intensity (CUHII) during 2000–2020. The STFT of CUHII showed a close relationship between the CUHI and the background meteorological forcing at intra‐annual, weather and intra‐daily scales. The intra‐annual spectrum of CUHII showed an increasing trend with a V‐shaped mode. The local climatic backgrounds of different cities can lead to differences in the seasonal development of the CUHI. The intra‐daily spectrum of CUHII showed an increasing trend due to the asymmetry in the day/night development of the CUHI. Increasing Western Pacific Subtropical High Intensity can enhance the seasonal and diurnal fluctuations of CUHII. The weather‐scale spectrum of CUHII was mainly controlled by weather system evolution, showing that cold waves and heat waves can increase the CUHII over a long duration. Our findings indicate that the evolution of CUHII is a nonlinear and complex process that is directly related to multi‐timescale background climate forcing. Key Points: Using a short‐time Fourier transform to study the multi‐timescale evolution of the canopy urban heat island intensity (CUHII)Close relationships existed between CUHII and the background meteorological forcing at intra‐annual, intra‐daily, and weather scalesThe frequency of cold/heat waves in Beijing showed a significant negative correlation with the weather‐scale spectral intensity of the CUHII [ABSTRACT FROM AUTHOR]

We present the twisted electromagnetic sinc-correlation Schell-model (EM TSSM) beam as an extension of the cylindrical sinc Schell-model beam and analyze the necessary source parameter conditions to generate a physically viable beam. Furthermore, we thoroughly investigate the propagation properties of the EM TSSM beam in atmospheric turbulence using the extended Huygens-Fresnel integral, explicitly focusing on spectral intensity, degree of polarization (DOP), and degree of coherence (DOC). It shows that the twisted phase has a noticeable impact on the intensity profiles of these beams, causing them to exhibit rotation and self-splitting while still maintaining their shape in free space. Moreover, during propagation through a turbulent atmosphere, it exhibits self-combining properties over a long range and recovers the plat-topped distribution. Compared with the sinc Schell-model beam without the twisted phase, the DOP distribution of such a beam can rotate around its distribution center. As these beams propagate through turbulent atmospheres, they can self-heal their DOP distribution within specific ranges affected by atmospheric turbulence. A twist factor causes non-unidirectional rotation of the DOC distribution in free space. The DOC gradually transforms from multi-strip profiles into a Gaussian-like distribution. Furthermore, the beam parameters play a crucial role in shaping the DOC. The results will be useful in optical trapping and optical communication. [ABSTRACT FROM AUTHOR]

Maturity is a major fiber trait that affects the processing and performance of cotton fiber. Rapid and accurate identification of fiber maturity phenotypes and genotypes is of importance to breeders. Previous studies showed that either conventional fiber measurements or attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) analysis discriminated the immature fiber (im) phenotype from the wild type (WT) mature fiber phenotype in a segregating F2 population from a cross between two upland cotton lines differing in fiber maturity. However, both conventional fiber property measurement methods and FT-IR analyses with current algorithms could not detect the subtle differences among the WT fibers composed of two different genotypes, WT homozygosity (WT-homo) and WT heterozygosity (WT-hetero). This research explored the FT-IR method, in combination with soft independent modeling of class analogy of principal component analysis (SIMCA–PCA), for the discrimination of WT fiber phenotypes consisting of two different genotypes (WT-homo and WT-hetero). The new approach enabled the detection of IR spectral intensity differences between WT-homo and WT-hetero fibers. Successful classification originated from a distinctive spectral difference in the low-wavenumber region (<700 cm–1) between WT-hetero fibers and WT-homo fibers. This observation emphasized that ATR FT-IR with a SIMCA–PCA approach would be a sensitive tool for classifying the WT fibers demonstrating minor phenotypic differences. The improved sensitivity of the infrared method may provide a way of dissecting genotype–phenotype interactions of cotton fibers rapidly and efficiently. Graphical abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

The presence of a chiral or chirally perturbed chromophore in the molecule under investigation is a fundamental requirement for the appearance of a circular dichroism (CD) spectrum. For native and for most of the substituted cyclodextrins, this condition is not applicable, because although chiral, cyclodextrins lack a chromophore group and therefore have no characteristic CD spectra over 220 nm. The reason this method can be used is that if the guest molecule has a chromophore group and this is in the right proximity to the cyclodextrin, it becomes chirally perturbed. As a result, the complex will now provide a CD signal, and this phenomenon is called induced circular dichroism (ICD). The appearance of the ICD spectrum is clear evidence of the formation of the complex, and the spectral sign and intensity is a good predictor of the structure of the complex. By varying the concentration of cyclodextrin, the ICD signal changes, resulting in a saturation curve, and from these data, the stability constant can be calculated for a 1:1 complex. This article compares ICD and NMR spectroscopic and molecular modeling results of cyclodextrin complexes of four model compounds: nimesulide, fenbufen, fenoprofen, and bifonazole. The results obtained by the different methods show good agreement, and the structures estimated from the ICD spectra are supported by NMR data and molecular modeling. [ABSTRACT FROM AUTHOR]

Spatio-temporal dynamics of a Grimm-type microsecond pulsed glow discharge (μPGD), that operates in abnormal glow regime in argon at 6 mbar, is presented. The occurrence of a high current peak during the ignition of the discharge was analyzed and the importance of taking into account the displacement current was pointed out. A development of the electron excitation temperature of argon atoms and argon ions was measured at several distances from the cathode. Spatio-temporal evolution of the intensity of selected spectral lines of atoms and ions of argon and copper were measured and analyzed during the three phases of the discharge development: pre-peak, steady-state and afterglow. The spectral line emissions have different behavior during the pre-peak and the afterglow of the discharge – the lines with low upper-level energies get the maximum intensity in the pre-peak period, while the lines with high upper-level energies get the maximal intensity in the afterglow period. The time of the appearance of the afterpeak maxima and the afterpeak decay time are shorter for the ions than for the atoms. The results are explained primarily in terms of three-body recombination processes and ion mobilities. Carefully arranged and conducted experiment with a large amount of experimental data, together with analysis of excitation and deexcitation processes, could be useful for more precise modeling of μPGD, as well as a note for selection of adequate spectral lines and discharge conditions for more accurate analytical measurements. [ABSTRACT FROM AUTHOR]

[Objective] Fire is a frequent security incident in computer laboratories; it might devastate internal equipment and stored data and seriously threaten the lives and properties of personnel. Therefore, an effective fire warning method must be adopted to recognize the potential fire status in computer laboratories and promptly transmit graded fire warning information. However, the existing fire warning methods based on the Euclidean, Lance--Williams, and cosine distances suffer from the problems of low warning accuracy and inability to recognize the potential fire status of computer laboratories in time. Then, a fire risk early warning method for computer laboratories is proposed based on the discrimination of Mahalanobis distance. [Methods] First, various sensors arranged in the computer laboratory are utilized to detect the relevant gas concentration, temperature, radiant light intensity, current magnetic field intensity, and smoke and dust concentrations in the computer laboratory. Subsequently, reference matrices of different states are established based on typical samples, and different elements in the vectors composed of the detected indicator contents are given different weights. Afterward, the fire to which the indicator content belongs is determined based on the weighted Mahalanobis distance. Subsequently, the fire hazard level to which the indicator content belongs is determined based on the weighted Martensitic distance (i.e., very-high-risk level, higher-risk level, medium-risk level, medium-to low-risk level, and low-risk level). Finally, different solutions are adopted according to different fire hazard levels to eliminate fire hazards in computer laboratories. In the experimental phase, first, the coverage area of each sensor and the minimum number of sensors required to implement the method by calculation based on the size of a real computer laboratory are obtained. Second, a certain class of sensors in computer laboratories is removed, and the remaining four environmental data on fire risk warnings in computer laboratories are used to determine the reasonable weights corresponding to the relevant gas concentration, temperature, radiant light intensity, current magnetic field intensity, and smoke and dust concentrations in the Mahalanobis distance discrimination. Afterward, the location of each sensor is changed according to different distribution rules to determine the optimal distribution of sensors in the computer laboratory. Finally, with the deployment of different numbers of sensors in the computer laboratory, the fire risk warning method based on weighted Mahalanobis distance discrimination in the computer laboratory is compared with the fire risk warning methods based on Euclidean, Lance--Williams, and cosine distances to further validate the effectiveness and accuracy of the proposed method. [Results] The experimental results show that, compared with other fire risk warning methods, the proposed method based on weighted Mahalanobis distance discrimination exhibits a high warning accuracy. Its overall fire warning accuracy is maintained at approximately 80% even when the minimum number of sensors are placed in the computer laboratory, and the average warning accuracy of the method is increased to 90% after increasing the number of sensors in the computer laboratory. [Conclusions] Therefore, the proposed method based on weighted martensitic distance discrimination is more accurate and effective. [ABSTRACT FROM AUTHOR]

Line-intensity mapping (LIM) is an emerging technique to probe the large-scale structure of the Universe. By targeting the integrated intensity of specific spectral lines, it captures the emission from all sources and is sensitive to the astrophysical processes that drive galaxy evolution. Relating these processes to the underlying distribution of matter introduces observational and theoretical challenges, such as observational contamination and highly non-Gaussian fields, which motivate the use of simulations to better characterize the signal. In this work we present skyline  , a computational framework to generate realistic mock LIM observations that include observational features and foreground contamination, as well as a variety of self-consistent tracer catalogues. We apply our framework to generate realizations of LIM maps from the multidark planck 2 simulations coupled to the universemachine galaxy formation model. We showcase the potential of our scheme by exploring the voxel intensity distribution and the power spectrum of emission lines such as 21 cm, CO, [C  ii ], and Lyman-α, their mutual cross-correlations, and cross-correlations with galaxy clustering. We additionally present cross-correlations between LIM and submillimetre extragalactic tracers of large-scale structure such as the cosmic infrared background and the thermal Sunyaev-Zel'dovich effect, as well as quantify the impact of galactic foregrounds, line interlopers, and instrument noise on LIM observations. These simulated products will be crucial in quantifying the true information content of LIM surveys and their cross-correlations in the coming decade, and to develop strategies to overcome the impact of contaminants and maximize the scientific return from LIM experiments. [ABSTRACT FROM AUTHOR]

The intense current of lightning plasma can emit radiation across various parts of the electromagnetic spectrum. Spectral observation is an effective means to understand the radiation characteristics of lightning channels at different wavelengths. In this context, the spectra and channel current of a single-stroke lightning flash to Canton Tower were acquired from the Tall-Object Lightning Observatory in Guangzhou using a slitless high-speed spectrograph and a Rogowski coil. Spectral correction was applied for enhanced spectral analysis. The relationship between the intensities of different spectral lines and the directly measured current of the lightning channel was investigated for the first time. The results indicated that the duration of the ionic lines in the visible region can be up to one millisecond during the entire discharge process, which is clearly longer than the duration reported in previous research. There always exists a good exponential relationship (y = axb) between the intensities of ionic lines and the channel current with an exponent value (b) very close to 2 and with a coefficient of determination (R2 value) higher than 0.99, whereas the exponential relationship between many atomic lines and the channel current has an exponent value clearly smaller than 2 with a relatively lower R2 value, which implies that the intensities of ionic lines are evidently associated with the square of the current, while the intensities of atomic lines have relatively weak exponential correlation with the current. We also preliminarily verified this conclusion with temperature derived from the ionic and atomic lines. The results indicated that due to the time integral of the current squared, the cooling rate of the temperature derived from the ionic lines in the channel core is not significant when the current decreases, while the cooling rate of the temperature derived from the atomic lines of the surrounding corona sheath channel presents a pronounced decline with a decrease in current. [ABSTRACT FROM AUTHOR]

Generalized Hermite cosh Gaussian (GHCG) beam has been produced as generalized beams with special profiles. The analytical expression of the intensity spectral of pulsed chirped GHCG beam passing through turbulent oceanic is derived using extended Huygens-Fresnel principle and the Fourier Transform method. The study examines various factors, including ocean turbulence, transverse position, and initial beam parameters, to understand their influence on the spectral intensity of the pulsed chirped GHCG beam by using numerical simulations. Moreover, the effects of both optical parameters and oceanic turbulence parameters on spectral shifts at different observation positions are discussed in detail. The blue shift and red shift of the spectrum on the axis increase with the increase of the transverse distance, which provides valuable insights into the behavior of the pulsed chirped GHCG beam as it propagates through turbulent oceanic environments. These findings offer a comprehensive understanding of the spectral transition of the pulsed chirped GHCG beam in such conditions and hold potential applications in information coding and transmission for marine communication systems. [ABSTRACT FROM AUTHOR]

The surface chemistry of a plasma SiC nanopowder was characterized by X-ray photoelectron spectroscopy using a tunable synchrotron X-ray source. The sample surface was representative of SiC nanopowder surfaces in interaction with ambient air, with no significant influence from carbonaceous deposits. By choosing an incident photon energy in the range 200–1200 eV, the escape depth of photoelectrons was altered from 0.5 to 3 nm based on the C 1 s , Si 2 p and O 1 s core-level transitions. The spectral series gave evidence for surface enrichment of silica and sp 2-bonded elemental carbon. Several models of surface enrichment were tested against the spectral intensities as a function of escape depth. This analysis led to sp 2-carbon islands and two types of oxidation depths. While on the larger part of the surface, the silica is only a near-monolayer in thickness, there are surface regions that are oxidized to a depth of ≥3 nm. These heavily oxidized regions are attributed to defected open channel pores on the outer surface of nanoparticle agglomerates, based on the previous electron tomography results. [ABSTRACT FROM AUTHOR]

Bioaerosol emission at various WWTP treatment units has drawn attention due to their potential negative impacts on human health. This study conducted a bibliometric analysis of the global research on bioaerosol emissions from WWTPs from 1995 to 2022. The Scopus database was used to identify relevant articles and research trends, major contributors in the field, and recent developments. The study examined 122 articles in the field of bioaerosols in WWTPs. The analysis findings showed that publications and citations peaked in 2022, with values of 25 and 818, respectively. At the beginning of the study period, the USA, Poland, and Italy led the publications' ranking, but with time, China emerged as the most influential country in the field. Recent advances in the field have revealed that spectral intensity bioaerosol sensors have contributed to the faster and more reliable identification and classification of bioaerosols. It was also observed that probabilistic techniques relying on mathematical models and assumptions to ascertain the risks associated with bioaerosols may result in false interpretations. Despite their high cost, epidemiological studies were best for assessing plant workers' health risks. The outbreak has raised questions about accurately evaluating and modeling SARS-CoV-2 persistence, infectivity, and aerosolization over WWTP sites and environmental factors. Finally, the study highlighted the potential of three control treatment approaches: carbon absorption, UV irradiation, and ozone treatments, which proved efficient in reducing bioaerosol emissions. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the secrecy performance of a dual-hop hybrid radio frequency–visible light communication (RF–VLC) system in which we consider a single source antenna (S) transmitting data signals via RF channel through decode and forward (DF) relay (R) toward an authorized receiving antenna (D) at the destination via VLC channel. In this system, we assume that the eavesdropper (E) attempts to eavesdrop the RF channel (S,R) during transmission of the signal. The relay decodes the incoming RF signal into corresponding optical signal and retransmits toward destination via VLC channel (R,D). The RF and VLC channels of the hybrid system are modelled using generalized-K fading distribution and generalized Lambertian radiant intensity distribution respectively. Also the receiver is assumed to be mobile and its mobility is defined by random waypoint (RWP) model. The channels statistics are used to derive the exact analytical expressions for average secrecy capacity and intercept probability in terms of Meijer's G-function. The derived closed form analytical expressions are the efficient tool to illustrate the impact of variation in different channel parameters on the secrecy performance, namely, shadowing parameters of RF channel, field of view (FOV), semiangle, and the order of Lambertian emission of the VLC channel. Further, numerical analysis is carried out to support the mathematical analysis of the RF–VLC hybrid system. [ABSTRACT FROM AUTHOR]

We obtain the kinematic distributions of stars (synthetic model line absorption) and ionized gas (H α line emission) for star-forming regions residing in Calar Alto Legacy Integral Field Area survey tidally perturbed (perturbed) and non-tidally perturbed (control) galaxies. We set the uncertainties of the velocity dispersion by measuring the statistical variability of the data sets themselves. Using these adopted uncertainties and considering the sensitivity of the grating device, we establish thresholds of reliability that allow us to select reliable velocity dispersions. From this selection, we pair the star-forming spaxels between control and perturbed galaxies at the closest shifts in velocity (de-redshifting). We compare their respective distributions of velocity dispersion. In perturbed galaxies, median velocity dispersions for the stellar and gaseous components are minimally higher and equal, respectively, than those in control galaxies. The spread in velocity dispersion and the velocity shift–velocity dispersion space agree with this result. Unlike the well-known trend in strongly interacting systems, the stellar and ionized-gas motions are not disturbed by the influence of close companions. For the gaseous component, this result is due to the poor statistical variability of its data, a consequence of the tightness in velocity dispersion derived from high spectral line intensities. This analysis concludes the series, which previously showed star-forming regions in galaxies with close companions undergoing more prominent gas inflows, resulting in differences in their star formation and consequent metal content. [ABSTRACT FROM AUTHOR]

A detailed investigation of the explosion mechanism of hydrogen (H 2) - propane (C 3 H 8) mixture gas is the prerequisite for effective prevention of its explosion. This study delved into the explosion pressure and the spectral intensity of free radicals within the H 2 -C 3 H 8 mixture, conducting a comprehensive investigation of reaction kinetics to elucidate reaction rates, elementary reaction sensitivity, and reaction path. Our findings unveiled a relationship between hydrogen augmentation and heightened explosion pressure, particularly when the hydrogen mixing ratio exceeded 80.0%, and the explosion index reached to St3 level, thereby indicating an exceeding safety risk. Moreover, a discernible augmentation was observed in the spectral intensities of H•, OH•, and O• radicals in tandem with an increased hydrogen mixing ratio. Notably, a linear correlation emerged between the explosion pressure and the spectral intensities of these free radicals. R1: H•+O 2 =O•+OH• was the most important reaction step. As the ignition starts, H 2 burns prior to C 3 H 8 , giving rise to the generation of H• radicals. These H• radicals, in turn, actively participate in the dehydrogenation of C 3 H 8 , effectively catalyzing the overall chemical reaction. These results can provide potent scientific support and guidance for the prevention and management of H 2 -C 3 H 8 explosions. [ABSTRACT FROM AUTHOR]

The poor long-term repeatability of laser-induced breakdown spectroscopy (LIBS) is a barrier to its general adoption. To date, its causes and the mechanisms involved are poorly understood. Despite the potential impact of variations in ambient operating conditions such as ambient temperature and humidity, these factors have not been thoroughly investigated, especially ambient humidity. This study investigates the influence of ambient humidity on LIBS spectra. The ambient humidity of a pure copper sample was adjusted in real-time and the LIBS spectra were acquired. The results indicate that the H I 656.28 nm intensity increased with humidity, whereas the variation of the Cu I line intensity with humidity depended on the laser energy. The intensity of the Cu I 510.55 nm decreased with humidity at 8 mJ and 13 mJ, and increased with humidity at 18 mJ, 30 mJ, and 50 mJ. An investigation of the underlying mechanism suggested that at a high ambient humidity, sample ablation increased, but the lifetime of the induced plasma was reduced. The two mechanisms increased and decreased the spectral intensity, respectively, and determined the variation in the Cu I line intensity with humidity. This study demonstrates that ambient humidity affects the LIBS spectral intensity and should be considered especially for long-term LIBS measurements or open-air measurements. [ABSTRACT FROM AUTHOR]

Underwater laser-induced breakdown spectroscopy (underwater LIBS) has attracted attention as an on-site analytical technique for deep-sea investigation, but it suffers from serious signal fluctuation. In this study, we analyzed a copper (Cu) plate immersed in a sodium chloride (NaCl) aqueous solution by underwater LIBS and investigated the signal fluctuation caused by the repeated irradiation at a fixed position. The intensity of Cu and Na emission lines increased with increasing the number of laser shots. We found that there were strong correlations between the spectral line intensity and the collapse time of the laser-induced bubble. By normalizing the spectral line intensity with the bubble collapse time after removing the offset, the relative standard deviations of Cu and Na intensity obtained for the repeated irradiation were reduced from 41.4% to 27.0% and 28.8% to 17.7%, respectively. We also confirmed that elimination of the data obtained with the first irradiation of a fresh surface and the use of the spectral line intensity of dissolved species as a normalization parameter were valid for improving the precision of analysis. The results suggest simple approaches to improve the quantitative performance of underwater LIBS, which are easily applicable to the existing system. [ABSTRACT FROM AUTHOR]

A model of a generalized pulse source, whose complex degree of temporal coherence is described by a function of the nth power difference of two instants, was constructed. As examples, we consider the generalized Gaussian and multi-Gaussian Schell-model pulse sources and study their propagation in dispersive media. It is indicated that such pulse beams present unique self-focusing, off-axis self-shifting and asymmetric self-splitting characteristics by adjusting the power exponent and phase parameters. Further, we explicitly discuss how the coherence time, summation factor as well as the dispersive coefficient significantly affect the self-focusing and self-shifting behaviors of the pulse beam. The results will benefit some applications involving pulse shaping, optical trapping and remote sensing. [ABSTRACT FROM AUTHOR]