Molecular Bands Research Articles

Molecular beam epitaxy and band structures of type-II antiferromagnetic semiconductor EuTe thin films

The rare-earth Eu-based compounds with a unique half-filled 4f orbital have attracted an amount of research interest recently. Here, we synthesized EuTe(001) single-crystal thin films on SrTiO3(001) substrate via molecular beam epitaxy (MBE). The scanning tunneling microscopy and x-ray diffraction results indicate that the grown EuTe thin films orientated as EuTe[100]//SrTiO3[110] in plane. In the angle-resolved photoemission spectroscopic (ARPES) measurements, the grown EuTe films show a semiconductive band structure with the valence band maximum lying on the center point of the Brillouin zone. The bandgap size of EuTe was further identified by the optical transmission spectra as 2.2 eV. The antiferromagnetic transition temperature of the grown EuTe film is 10.5 K measured by a superconductive quantum interference device (SQUID). Our results provide important information on the fundamental electronic structures for the further research and applications of the Eu-based compounds.

Utilization of D2 molecular band emission for electron density measurement

D2 molecular band emission observed at a wavelength range of λ∼557−643nm is utilized to measure electron density, ne, in D plasmas of the PISCES-A and PISCES-RF linear plasma devices. The D2 band is divided at λ=593nm to make an intensity ratio, D2L (∼557–593nm)/D2R (∼593–643nm), where D2L consists predominantly of the g3Σg+3dσ, h3Σg+3sσ, i3Πg3dπ, j3Δg3dδ→c3Πu2pπ transitions, while D2R mainly includes the d3Πu3pπ→a3Σg+2sσ Fulcher band emission. It is experimentally found that D2L/D2R depends strongly on ne with little Te dependence in ranges of ne∼(0.031−6.1)×1018 m−3 and Te∼2.3−13.9eV. This observed trend is consistent with collisional-radiative model calculations using Yacora on the Web.

Surface cleaning with atmospheric pressure plasma jet investigated by in-situ optical emission spectroscopy and laser-induced breakdown spectroscopy

Cleaning of surfaces with atmospheric pressure plasma jet (APPJ) is investigated by in-situ optical emission spectroscopy (OES) and laser-induced breakdown spectroscopy (LIBS). The APPJ device operates a spark discharge of kW power in Argon gas flow resulting in a powerful plasma jet expanding into air. For cleaning experiments samples are coated with lubricant layers of 1.1 to 7.1 µm thickness. Light collected at the sample surface during APPJ treatment is analyzed spectroscopically and used to monitor the cleaning process. LIBS chemical imaging delivers spatial cleaning profiles of plasma treated surfaces. From measured emission intensities of CN molecular band and Na atomic line the cleaning efficiencies for carbon and Na containing contaminants are determined. The power of APPJ plasma generator, distance between sample and jet nozzle, scan speed, and Argon gas flow are varied to optimize the surface treatment. Thermal and non-thermal processes contribute to cleaning. For the carbon containing contaminant thermal processes are dominating (∼90 %) while also non-thermal processes (∼30–45 %) are relevant for the Na containing component. A cleaned surface area per time from 0.3 to 10 cm2/s is investigated. Cleaning efficiency up to 95 % is obtained highlighting the potential of APPJ surface cleaning under ambient conditions.

Temporal Changes in the Infrared Spectra of Magellanic Carbon Stars

A Medium-Resolution Spectrometer on a Mid-Infrared Instrument on the JWST obtained spectra of three carbon stars in the Large Magellanic Cloud. Two of the spectra differ significantly from spectra obtained ∼16–19 years earlier with the Infrared Spectrograph on the Spitzer Space Telescope. The one semi-regular variable among the three has changed little. The long-period Mira variable in the sample shows changes consistent with its pulsation cycle. The short-period Mira shows dramatic changes in the strength of its molecular absorption bands, with some bands growing weaker and some stronger. Whether these variations result from its pulsation cycle or its evolution is not clear.

J-PLUS: Beyond Spectroscopy. III. Stellar Parameters and Elemental-abundance Ratios for Five Million Stars from DR3

We present a catalog of stellar parameters (effective temperature T eff, surface gravity logg , age, and metallicity [Fe/H]) and elemental-abundance ratios ([C/Fe], [Mg/Fe], and [α/Fe]) for some five million stars (4.5 million dwarfs and 0.5 million giant stars) in the Milky Way, based on stellar colors from the Javalambre Photometric Local Universe Survey (J-PLUS) DR3 and Gaia EDR3. These estimates are obtained through the construction of a large spectroscopic training set with parameters and abundances adjusted to uniform scales, and trained with a kernel principal component analysis. Owing to the seven narrow/medium-band filters employed by J-PLUS, we obtain precisions in the abundance estimates that are as good as or better than those derived from medium-resolution spectroscopy for stars covering a wide range of the parameter space: 0.10–0.20 dex for [Fe/H] and [C/Fe], and 0.05 dex for [Mg/Fe] and [α/Fe]. Moreover, systematic errors due to the influence of molecular carbon bands on previous photometric-metallicity estimates (which only included two narrow/medium-band blue filters) have now been removed, resulting in photometric-metallicity estimates down to [Fe/H] ∼ −4.0, with typical uncertainties of 0.40 dex and 0.25 dex for dwarfs and giants, respectively. This large photometric sample should prove useful for the exploration of the assembly and chemical-evolution history of our Galaxy.

Mira Variables Based on Emission Lines in LAMOST DR9

We present a sample of 335 Mira variables, extracted from DR9 of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey. These variables are characterized by the Balmer emissions (Hδ, Hγ, Hβ, and Hα) and the metal emissions (Fe i λ λ 4202, 4308, 4376, and Mg i λ4571) observed in M giant spectra. We distinguished oxygen-rich stars from carbon-rich stars through the identification of carbon molecular bands present in the optical spectra. For the oxygen-rich stars we examined multiple attributes, such as the link between line strength and bolometric luminosity, and the connection between atmospheric parameters and their periods. We observed that Fe i λ λ 4202, 4308 showed a significantly gradual progression, which can be postulated to trace the fluorescent emission resulting from pulsation shocks. Regarding the correlation between T eff and the period, T eff remains relatively constant over varying periods, with no clear trend, while both log g and [Fe/H] show a decreasing trend within a period range of 450 days, and this decreasing of the log g trend is consistent with the results in the literature. To shed more light on the variations of Balmer lines, we showcase time-series spectra for two objects, demonstrating that the Balmer lines reach their peak intensity during the brightest phase of the stellar cycle.

Helium Abundance of the Sun: A Spectroscopic Analysis

Determining the He/H ratio in cool stars presents a fundamental astrophysical challenge. While this ratio is established for hot O and B stars, its extrapolation to cool stars remains uncertain due to the absence of helium lines in their observed spectra. We address this knowledge gap by focusing on the Sun as a representative cool star. We conduct spectroscopic analyses of the observed solar photospheric lines by utilizing a combination of MgH molecular lines and neutral Mg atomic lines including yet another combination of CH and C2 molecular lines with neutral C atomic lines. Our spectroscopic analyses were further exploited by adopting solar model atmospheres constructed for distinct He/H ratios to determine the solar photospheric helium abundance. The helium abundance is determined by enforcing the fact that for an adopted model atmosphere with an appropriate He/H ratio, the derived Mg abundance from the neutral Mg atomic lines and that from the MgH molecular lines must be the same. The same holds for the C abundance derived from neutral C atomic lines and that from CH lines of the CH molecular band and C2 lines from the C2 Swan band. The estimated He/H ratio for the Sun is discussed based on the one-dimensional local thermodynamic equilibrium model atmosphere. The helium abundance (He/H = 0.091−0.014+0.019 ) obtained for the Sun serves as a critical reference point to characterize the He/H ratio of cool stars across the range in their effective temperature.

On detection of BaO molecular lines in sunspot spectrum

ContextSpectral lines of diatomic molecules are perfect tools for studying the structure of sunspots and their temperature layers and magnetic sensitive absorption features, which are typically higher than in atomic lines. The integrated intensities of a few bands in the rotational structure of the astrophysically significant A1Σ+−X1Σ+and A′1Π−X1Σ+ systems of barium monoxide (BaO) have been measured experimentally using band spectra. An analysis of the prominent lines of (0, 0; 1, 1; 2, 2) bands of A1Σ+−X1Σ+transition and (0, 0; 1, 1; 2, 2) bands of A′1Π−X1Σ+transition with those of sunspot umbral spectrum. The effective rotational temperatures of the A′1Π−X1Σ+transition of BaO in the sunspot umbral spectrum are found to be in the range of 1600 K to 3200 K. AimsAn analysis of BaO prominent rotational molecular lines of A1Σ+−X1Σ+and A′1Π−X1Σ+transition with those of sunspot umbral spectral lines. To find the significant values of radiative transition parameters, vibrational temperature and the effective rotational temperature of the molecule in celestial objects. MethodsCalibrated the rotational structure of molecular band heads and lines for and A1Σ+−X1Σ+and A′1Π−X1Σ+ransitions in laboratory spectrum using most precise Hartmann's technique. High resolution FTS sunspot umbral spectra from NSO/Kitt Peak were used to detect rotational molecular lines due to the A′1Π−X1Σ+transition of the BaO molecule using the method of line coincidence. The effective rotational temperature was derived from the variation of equivalent width (W) with rotational quantum number (J) of spectrally well resolved rotational lines of a band in umbral spectrum. The triangular profile approximation method was used to estimate the equivalent width of the well resolved spectral lines. ResultsThe effective rotational temperatures of the A′1Π−X1Σ+transition of BaO in the sunspot umbral spectrum are found to be in the range of 1600 K to 3200 K. It is compared with other results with a view to obtaining useful physical parameters. This is an evidence to ascertain the possible presence of BaO molecule in solar spectrum in different layers. ConclusionsUnblended rotational lines due to the band of BaO, provide a good range of temperatures for the study of absorbing layers in umbral spectra. The A′1Π−X1Σ+transition of BaO molecular lines is found to be very sensitive to effective temperature. Radiative transition parameters data of these lines, in contrast to intensity measurements, provide us with more direct and detailed information to study the coolest parts of sunspot umbrae.

Fractionation, characterization, and assessment of nutritional and immunostimulatory protein-rich polysaccharide-protein complexes isolated from Lentinula edodes mushroom

This study aimed to fractionate and characterize the protein-rich polysaccharide-protein (PSP) complexes from a well-known edible mushroom, Lentinula edodes, and assess their nutritional and immunostimulatory properties. Crude PSP isolated from the mushroom water extract was purified by anion exchange chromatography, yielding fractions PSP-F1 and PSP-F2 containing 66.1 % and 74.0 % protein, respectively. Both fractions exhibited primarily β-sheet and random-coil protein structures, though the crude PSP fraction exhibited an additional α-helix structure. On SDS-PAGE, PSP-F1 showed two molecular weight bands, one below 10 kDa and another at 34 kDa, and PSP-F2 showed several bands, one below 10 kDa and others between 34 and 95 kDa. The nutritional value of essential and non-essential amino acid profiles was in the order of PSP-F2 > PSP-F1 > crude PSP; the amino acid ratio coefficient values of the crude PSP, PSP-F1, and PSP-F2 were 63 %, 67 %, and 72 %, respectively. The combination of PS and PSP fractions exhibited stronger immunoactivity than PSP-F1 or PSP-F2 alone. PSP-F2 showed a higher immunostimulatory activity than PSP-F1 in RAW264.7 cell culture. PSP-F2 was also more abundant of easily absorbed high-quality proteins. The results provide useful references for dietary and medicinal uses of PSP fractions in L. edodes and other edible mushrooms.

UT-1 Transporter Expression in the Spiny Dogfish (Squalus acanthias): UT-1 Protein Shows a Different Localization in Comparison to That of Other Sharks.

The original UT-1 transporter gene was initially identified in the spiny dogfish (Squalus acanthias), but localization of the UT-1 protein was not determined. Subsequent UT-1 expression was shown to localize to the collecting tubule (CT) of the shark nephron in other shark species, with expression in a closely related chimaera species also located additionally at a lower level in the intermediate-I segment (IS-I) of the nephron. In spiny dogfish, two UT-1 splice variants are known (UT-1 long and short), and there was also a second UT-1 gene described (here termed Brain UT). In this study, a second splice variant of the second Brain UT gene was discovered. Expression profiles (mRNA) of UT-1 long and short and Brain UT were determined in a number of spiny dogfish tissues. Quantitative PCR in kidney samples showed that the level of the short variant of UT-1 was around 100 times higher than the long variant, which was itself expressed around 10 times higher than Brain UT cDNA/mRNA (in kidney). For the long variant, there was a significantly higher level of mRNA abundance in fish acclimatized to 75% seawater. Ultimately, three UT-1 antibodies were made that could bind to both the UT-1 short and long variant proteins. The first two of these showed bands of appropriate sizes on Western blots of around 52.5 and 46 kDa. The second antibody had some additional lower molecular weight bands. The third antibody was mainly bound to the 46 kDa band with faint 52.5 kDa staining. Both the 52.5 and 46 kDa bands were absent when the antibodies were pre-blocked with the peptide antigens used to make them. Across the three antibodies, there were many similarities in localization but differences in subcellular localization. Predominantly, antibody staining was greatest in the intermediate segment 1 (IS-I) and proximal (PIb) segments of the first sinus zone loop of the nephron, with reasonably strong expression also found at the start and middle of the late distal tubule (LDT; second sinus zone loop). While some expression in the collecting tubule (CT) could not be ruled out, the level of staining seemed to be low or non-existent in convoluted bundle zone nephron segments such as the CT. Hence, this suggests that spiny dogfish have a fundamentally different mode of urea absorption in comparison to that found in other shark species, potentially focused more on the nephron sinus zone loops than the CT.

Morphology-Dependent Interaction between Tetraphenylporphyrins and a Metal Oxide Surface: Electronic Signature, Photo Physics, and Chemical Interaction

Porphyrin-substrate hybrid systems are the building blocks in a series of materials, such as organic light-emitting diodes, chemical sensors, dye-sensitized solar cells and catalysts. Functional layers and 2D nanostructures on surfaces enable sensors, and nanoscale optical and magnetic materials. 3D porphyrin structures are for instance used in controlling and manipulating light at subwavelength dimensions. Understanding and correctly describing the way molecules interact with the substrate and in thin-film structures gives a handle on geometrical and electronic device properties. Indeed, adsorption and film-formation have a relevant effect on the molecular electronic structure even in the absence of strong covalent bonding, namely in terms of level-alignment with substrate states in the former and polarization-induced renormalization of molecular band gaps in the latter.Using the case of Co(II)-tetraphenylporphyrin (CoTPP) on the MgO(100), we shine light on the adsorption at morphology-related low-coordinated surfaces sites and the effect of multilayer film formation from a theoretical perspective in a frame work of hybrid density functional theory and many-body perturbation theory. We simulate the photoemission spectra for relevant adsorption sites as a fingerprint with distinct site-related features in both valence and core-level regions of the electronic structure that are also observed in experiments on MgO(100) films on Ag(100) and thus aid the identification of sites. Effects of the formation of porphyrin films on the electronic and optical properties will be outlined for H2TPP and MgTPP.We also highlight the self-metalation of H2TPP at morphology-related low-coordinated sites. Metalation is an important pathway for functionalization of porphyrin-based organic-inorganic structures. We address the self-metalation mechanism using ab initio molecular dynamics simulation at room temperature. While H2TPP is mobile on the pristine surface as the steric hindrance by phenyl rings prevents the physisorption of the macrocycle at a specific site, step edges or kink sites provide anchor points exposing low-coordinated, reactive oxygen-sites to hydrogens of the macrocycle. We report a spontaneous proton transfer at these sites forming an intermediate complex before the metalation occurs. This highlights the role of low-coordinated surface sites for the chemical interaction with the porphyrin.

Reaction mechanism of metal-free borophene catalyst electrochemical reduction of CO2

The utilization of electricity generated from renewable energy sources for carbon dioxide reduction reaction (CO2RR) to produce high-value chemical resources is of significant importance for reducing CO2 emissions and for energy storage. However, the search for environmentally friendly and efficient metal-free catalysts to facilitate CO2 conversion continues to present numerous challenges. This study employs density functional theory (DFT) calculation to explore the potential of two-dimensional metal-free borophene catalysts in the activation and conversion of CO2. Through molecular dynamics simulations, energy band and density of states analysis, the stability and electronic properties of metal-free borophene were thoroughly examined. The calculations demonstrated that two specific sites on electron-deficient zigzag borophene possess strong adsorption capabilities for CO2, enabling effective activation of CO2. Further investigation revealed that the reduction of CO2 at site 1 on zigzag borophene efficiently produces CO, HCOOH, CH3OH, and CH4, with the potential determining steps (PDS) requiring overpotentials of 0.11 V, 0.20 V, 0.38 V, and 0.52 V, respectively. In summary, this research provides theoretical foundation for the use of metal-free borophene as an efficient catalyst for CO2RR.

Exploring fluorine chemical evolution in the Galactic disk: The open cluster perspective

Open clusters are ideal tools for tracing the abundances of different elements because their stars are expected to have the same age, distance, and metallicity. Therefore, they serve as powerful tracers for investigating the cosmic origins of elements. This paper expands on a recent study by us, in which the element fluorine was studied in seven open clusters; here we add six open clusters and eight field stars. The primary objective is to determine the abundance of fluorine (F) to gain insight into its production and evolution. The magnesium (Mg) abundances were derived to categorize the field stars into high and low alpha disk populations. Additionally, cerium (Ce) abundances were determined to better understand the interplay between F and s-process elements. Our goal is to analyze the trend of F abundances across the Galactic disk based on metallicity and age. By comparing observational data with Galactic chemical evolution models, the origin of F can be better understood. The spectra were obtained from the high-resolution near-infrared GIANO-B instrument at the Telescopio Nazionale Galileo (TNG). For the derivation of the stellar parameters and abundances, the Python version of Spectroscopy Made Easy ( PySME ) was used. OH, CN, and CO molecular lines and band heads along with Fe I lines were used to determine the stellar parameters in the H-band region. Two HF lines in the K band ($ 2.28, and 2.33 mu m), three K-band Mg I lines ($ 2.10, 2.11, and 2.15 mu m), and two Ce II lines in the H band ($ 1.66, and 1.71 mu m) were used to derive the abundances of F, Mg, and Ce, respectively. F, Mg, and Ce abundances were derived for 14 stars from 6 OCs, as well as for 8 field stars. The F and Ce abundances were investigated as a function of metallicity, age, and galactocentric distance. We also compared our findings with different Galactic chemical evolution models. Our results indicate that asymptotic giant branch stars and massive stars, including a subset of fast rotators (whose rotation speed likely increases as metallicity decreases), are necessary to explain the cosmic origin of F. This finding is consistent with and, with the large sample size, reinforces the conclusion of our previous study.

Synthesis and structural, morphological, and chimico-optical properties of Sr2FeO4 Ruddlesden-Popper oxide

The citrate sol-gel process was used to produce Sr2FeO4 strontium ferrite powder. The method involves metallic nitrates, citric acid and distilled water as a solvent, followed by calcination. The Ruddlesden-Popper structure of the resulting compound was identified by XRD analysis. The different molecular structures and vibration bands were studied by FTIR. The morphology of the powder was analysed using SEM. Samples appear of good crystalline quality and with interesting nanostructure. We studied optical properties and determined the band gap energy to lie about 2.8 eV, Sr2FeO4 can thus absorb photons having a wavelength less than 444 nm, approximately, making this compound potentially interesting for applications.

Adsorption of SF6 decomposition gases (SO2 and SOF2) onto pristine and transition metal modified WSe2 monolayers: A systematic DFT study

The properties of SF6 characteristic decomposition products (SO2 and SOF2) adsorbed on intrinsic and transition metal atom modified WSe2 monolayers were studied based on the first principles. The adsorption structure, adsorption energy, electron transfer, density of states, electron differential density, work function, and desorption properties are comprehensively discussed. In addition, the charge transfer in the adsorption system was qualitatively analyzed by using the frontier molecular orbital theory and energy band. The results show that the pristine WSe2 monolayer has poor sensing performance for SO2 and SOF2. Effective modification methods can significantly increase the adsorption activity of the monolayer surface. The modification methods of transition metal atom adsorption and doping are discussed respectively. The modified monolayer all exhibit good sensing properties compared to the pristine monolayer due to the significant electronic hybridization between the impurity atoms and the gas molecules. Finally, the recovery response time of gas molecules from transition metal atom modified WSe2 monolayer is evaluated to evaluate its potential application in the detection and removal of fault gases in SF6 insulation equipment. Our work is not only important for predicting novel transition metal sulfide sensing materials, but also provides theoretical guidance for further developing WSe2-based sensors and scavengers for environmental monitoring applications.

Real-time determination of combustion degree by laser-induced breakdown spectroscopy

The combustion of fuels in industries is one of the sources of greenhouse gases, posing a considerable threat to human health and the natural environment. The monitoring of the combustion process and the measurement of combustion degrees, therefore, are crucial and significant. In this work, an experimental system was developed based on Laser-induced breakdown spectroscopy (LIBS). Charcoals with different combustion degrees were taken as samples, and in the LIBS spectra of charcoals, the characteristic line of C and the molecular bands of CN and CaO were observed. Moreover, a univariate calibration model based on the exponential fitting curve was constructed to predict the combustion degree according to the variation of the C I line intensity under different combustion degrees. Furthermore, different algorithms including support vector machine (SVM), partial least squares (PLS), random forest (RF), and convolutional neural network (CNN) were applied to establish the multivariate calibration model, and the prediction performance was compared according to the 10-fold cross-validation. Particle swarm optimization (PSO) was used to optimize hyperparameters of the selected SVM-based multivariate calibration model. Principal component analysis (PCA) and linear discriminant analysis (LDA) were employed to extract spectral features and reduce dimensions for the improvement of the model's performance, with the final root mean square error of prediction (RMSEP) and mean relative error (MRE) of the LDA-PSO-SVM calibration model of 0.035 and 3.877%, respectively. Finally, c. The results prove feasible to realize the real-time determination of combustion degree to control carbon emissions and monitor carbon concentration through the LIBS-based method with machine learning, which also provides new ideas for the application of LIBS in the atmospheric field.

New analysis of the Ã[formula omitted] X̃[formula omitted] electronic transition of the 12C16O[formula omitted] molecule: Improved molecular constants and Renner–Teller parameters

In this work, a new analysis of the transition Ã2Πu→X̃2Πg of the CO2+ molecule was carried out by Fourier Transform spectroscopy. More accurate wavenumbers allowed the improvement of molecular constants and band origins, leading to more reliable values for molecular parameters. Particularly in the first three vibrational levels v1′00 of symmetric stretching, as well as in the vibrational levels 010 and 110, in the excited electronic state Ã2Πu. Combining with previously reported data, it was possible to calculate, for the first time, a complete set of Renner–Teller parameters for the ground electronic state X̃2Πg.

Determination of the temperature of an object irradiated by microwaves using spectral pyrometry

Recently, due to increasing environmental requirements, microwave carbonization method has been widely investigated for the production of activated carbon from biomass waste. Microwave carbonization is a more energy efficient and environmentally friendly method compared to traditional carbonization in thermal furnaces, but to date there are still a number of questions about the reproducibility and temperature stability of this process. During microwave irradiation, the temperature of biomass samples changes continuously and complex physical and chemical processes occur in them. For deeper study of these processes and determination of optimal modes of microwave treatment it is necessary to know the temperature dynamics of biomass samples. For this purpose, the method of spectral pyrometry based on the allocation of sections of the spectra of thermal radiation of samples coinciding with the Planck spectrum was used. In the specified spectral sections these samples are gray emitters. The method is effective for an unknown emission coefficient, continuously varying with changes in the microstructure, chemical composition and phase state of the sample. The sample irradiated by microwaves was a sample of orthophosphoric acid-treated cotton down weighing 1 g. The microwave source was a magnetron-type generator with a maximum output power of 600 W and an operating frequency of 2450 MHz. Thermal spectra of the irradiated sample were recorded by small-size spectrometers of visible (350–760 nm) and near-infrared (650–1050 nm) ranges. The time of irradiation of samples by microwaves was varied in the range of 60–180 s. To process the obtained spectra, the program “Spectral Pyrometry” was used, which reads the recorded spectrum, processes it, plots it in the necessary coordinates and calculates the temperature. Analysis of the obtained results revealed different types of thermal radiation spectra of the irradiated sample - spectra similar to spectra of a completely black body, spectra with different temperature zones of the sample, spectra with atomic lines and molecular bands. The results obtained are useful for the study of microwave influence on various objects, research of processes occurring during carbonization of biomass, as well as for the development of more effective modes of production of activated carbons by microwave method.

Early screening and staging of melanoma using blood based on laser-induced breakdown spectroscopy

For melanoma, early screening could increase the cure rate, while staging helps to make treatment strategies. Blood sampling has advantages of little damage, convenient operation and low cost, which combined with laser-induced breakdown spectroscopy (LIBS) has been utilized for tumor diagnoses. Here, we proposed to accurately attain early screening and staging of melanoma blood using LIBS. The serum was collected from 25 melanoma mice and 10 healthy controls on the 7th, 14th, 21st and 28th days. Compared with k nearest neighbor (kNN), support vector machine (SVM) and back propagation neural network (BPNN) models, the adaptive boosting of BPNN (BP_AdaBoost) models had the best accuracies of 83.37 % for early screening and 96.18 % for staging, respectively. Using mutual information (MI) method to select features, the accuracies of BP_AdaBoost models were improved to 86.11 % for early screening and 96.91 % for staging, respectively. Besides, the difference significance of elements and molecular bands in the serum was examined by the Kruskal-Wallis (K-W) test. The test results showed that obvious differences of Ca and Na existed in both early screening and staging, while K and Mg made significant differences in staging, consistent with roles of Ca and Na in the whole process of tumor development and roles of K and Mg in tumor proliferation and metastasis. Overall, all results demonstrated that early screening and staging of melanoma could be accurately realized using blood based on LIBS.

Synthesis, crystal and molecular structure, DFT and antifungal activity studies of (E)-2-(3-methoxy-4-((6-(trifluoromethyl)pyrimidin-4-yl)oxy)styryl)-5-((2-(trifluoromethyl)benzyl)thio)-1,3,4-oxadiazole

Ferulic acid derivatives containing the 1,3,4-oxadiazole thioether and trifluoromethyl pyrimidine have displayed a wide array of pharmacological properties of interest to both medicinal and agricultural chemistry. This study focused on the synthesis of a new compound, (E)-2-(3‑methoxy-4-((6-(trifluoromethyl)pyrimidin-4-yl)oxy)styryl)-5-((2-(trifluoromethyl)benzyl)thio)-1,3,4-oxadiazole, with a ferulic acid skeleton, was synthesized via acetylation, condensation, cyclization, etherification, and thioetherification reactions. The title compound underwent comprehensive characterization using a variety of analytical techniques to gain a thorough insight into its molecular structure and properties. The structural arrangement of the compound was validated through X-ray diffraction and density functional theory calculations, while further analysis uncovered important physical and chemical attributes like molecular electrostatic potential and vibrational absorption bands. Moreover, the antifungal efficacy of the synthesized compounds was assessed, indicating their possible application in agriculture. This research lays the groundwork for the creation of novel compounds with antifungal properties.