Spectral Determination Research Articles

Solar radiation spectral composition determination program

The article describes the work of a software product designed to process the results of analytical studies on the effect of solar radiation intensity on its spectrum by bigarmonic interpolation. As a result of the program, the processed analytical data is converted into three-dimensional surfaces showing the dependencies of studies on the effect of solar radiation intensity on its spectrum, the height of the sun and geographical coordinates. The program allows you to determine areas with a certain percentage of the spectrum from the height of the sun and is used in research organizations, educational institutions and design organizations of the electric power industry.

The k-generalized Hermitian adjacency matrices for mixed graphs

This article gives some fundamental introduction to spectra of mixed graphs via its k-generalized Hermitian adjacency matrix. This matrix is indexed by the vertices of the mixed graph, and the entry corresponding to an arc from u to v is equal to the kth root of unity e2πik (and its symmetric entry is e−2πik); the entry corresponding to an undirected edge is equal to 1, and 0 otherwise. For all positive integers k, the non-zero entries of the above matrix are chosen from the gain set {1,e2πik,e−2πik}, which is not closed under multiplication when k⩾4. In this paper, for all positive integers k, we extract all the mixed graphs whose k-generalized Hermitian adjacency rank (Hk-rank for short) is 3, which partially answers a question proposed by Wissing and van Dam [34]. Furthermore, we study the spectral determination of mixed graphs with Hk-rank 2 and 3, respectively.

Quantitative Inversion Model Design of Mine Water Characteristic Ions Based on Hyperspectral Technology

In view of the problems of low measurement accuracy and repeated calibration during the use of coal mine water quality analysis, the hyperspectral reflection noncontact measurement technology was proposed to solve the existing problems. KCl, NaCl, pH, NaHCO3, and CaCl2were used to indicate the characteristic ion information of Na+, K+, Ca2+, Cl−, HCO3−, and pH mine water in the laboratory, and 2220 spectral data were obtained by spectral determination. Savitzky–Golay convolution smoothing was used to smooth and denoise the original spectral data of each ion, and the relationship between the spectrum and the concentration of each reagent was obvious after smoothing and denoising pretreatment. The principal component regression method was used to build the inversion model of each ion content, and through the modeling study, the prediction set of KCl was found: the coefficient R∧2 reaches 0.907, RPD is up to 2.7; the prediction set of NaCl was found: the coefficient R∧2 reaches 0.957, RPD is up to 3.1; the PH prediction set was found: the coefficient R∧2 reaches 0.785, RPD is up to 2.1; the prediction set of NaHCO3 was found: the coefficient R∧2 reaches 0.137, RPD is up to 1.2; the prediction set of CaCl2 was found: the coefficient R∧2 reaches 0.622, and RPD is up to 1.7. The results show that the hyperspectral method can play a better role in the extraction of K+, Cl−, Na+, Ca2+, and pH. It is difficult to extract HCO3− ions.

Variational Mode Decomposition Weighted Multiscale Support Vector Regression for Spectral Determination of Rapeseed Oil and Rhizoma Alpiniae Offcinarum Adulterants.

The accurate prediction of the model is essential for food and herb analysis. In order to exploit the abundance of information embedded in the frequency and time domains, a weighted multiscale support vector regression (SVR) method based on variational mode decomposition (VMD), namely VMD-WMSVR, was proposed for the ultraviolet-visible (UV-Vis) spectral determination of rapeseed oil adulterants and near-infrared (NIR) spectral quantification of rhizoma alpiniae offcinarum adulterants. In this method, each spectrum is decomposed into K discrete mode components by VMD first. The mode matrix Uk is recombined from the decomposed components, and then, the SVR is used to build sub-models between each Uk and target value. The final prediction is obtained by integrating the predictions of the sub-models by weighted average. The performance of the proposed method was tested with two spectral datasets of adulterated vegetable oils and herbs. Compared with the results from partial least squares (PLS) and SVR, VMD-WMSVR shows potential in model accuracy.

Results of Spectral Determination of Metals in Tissues Adjacent to the Sivash System Hip Endoprosthesis (Experimental Clinical Study)

After total hip replacement with Sivashs implants marked metallosis by chromium, cobalt and to a lesser degree by molybdenum develops in tissues contiguous with the joint. Titanium and tin are also determined in considerable amounts. At experimental (2 months to 5 years) and clinical (3 weeks to 15-19 years) follow up all metals are determined in the connective tissue. In bone tissue only small amounts of metals were present even in long term follow up. In short terms metallosis develops in the zones close to the mobility unit and gradually distributes along the bone marrow canal. As shown by experimental data metallosis is detected only as traces when the implant without friction units is used. In stable and unstable implants the degree of metallosis was the same although its incidence was higher when loosing developed. Our data confirm the possibility of the total hip prosthesis loosing but it develops gradually and manifest clinically in late terms.

Lemon Juice Catalysed Green Synthesis of Triazole Based Schiff Base, Its Physico-Chemical & Spectral Characterisation and Determination of its Binding Stoichiometry with Cu2+ ion

Abstract: In the recent years Environmental Pollution has emerged as a major challenge for human society. Since the start of Industrial Revolution in England, the amount of chemical waste and toxic substances are increasing exponentially in the environment. The traditional synthesis of chemical substances is accompanied by use of large amount of energy, harmful solvents and release of toxic substances in environment. The green synthesis aims to minimise the release and use of harmful toxic material in synthesis. In the present paper we have prepared a triazole derivative, 4-[(E)-Benzylideneamino]-5-methyl-2,4- dihydro-3H-1,2,4-triazole-3-thione through green synthetic route. The reaction was catalysed by lemon juice and it was carried out in solvent-free condition through mechano-chemical stirring method. The physico-chemical properties were studied. The FT-IR spectral analysis confirmed the structure of Schiff base. The stoichiometry of binding with Cu2+ was determined through Method of Continuous Variation. The Schiff base- metal ratio was found to be 1:1. Keywords: Green Synthesis, Mechano-Chemical Stirring Method, Triazole, Schiff Base, Lemon Juice, Physico-Chemical Properties, Job’s Plot, Stoichiometry of Binding.

Spectral determination of graphs with one positive anti-adjacency eigenvalue

The anti-adjacency matrix (or eccentricity matrix) of a graph is obtained from its distance matrix by retaining for each row and each column only the largest distances. This matrix can be viewed as the opposite of the adjacency matrix, which is, on the contrary, obtained from the distance matrix of a graph by keeping for each row and each column only the distances being 1. In this paper, we prove that the graphs with exactly one positive anti-adjacency eigenvalue are determined by the anti-adjacency spectra. As corollaries, the well-known (generalized) friendship graphs and windmill graphs are shown to be determined by their anti-adjacency spectra.

Rapid Assessment of Gasoline Quality by near-Infrared (NIR) Deep Learning Model Combined with Fractional Derivative Pretreatment

High-quality gasoline combustion reduces atmospheric emission. The evaluation of gasoline quality is needed reduce air pollution. The purity of gasoline is commonly quantitatively evaluated by octane number. Near-infrared (NIR) spectral determination of the octane number is practical for the rapid determination of gasoline quality. In NIR, the calibration model must be optimized for the improvement of the accuracy using deep learning methodologies. In this work, an algorithmic architecture was constructed for the deep learning of hybrid optimization by the combination fractional derivative (FD) and partial least squares (PLS). The design of FD-PLS methodology refers to the joint optimization for the data pretreatment and the calibration modeling. The FD order was tunable from 0.1 to 2.0 to search for the optimal pretreatment. Calibration models were established and trained by screening the optimal parameter combination for the model. The experimental results show that the calibration model was most improved by the FD-PLS deep learning with a 1.3 derivative order and 7 informative latent variables. The optimal model performed better than using integer derivative orders. In conclusion, the hybrid parameter optimization for the FD-PLS deep learning architecture improved the NIR assessment to characterize gasoline quality with quantitative prediction of the octane number. These results allow the production of high-quality gasoline to minimize air pollution.

Influence of electron-withdrawing groups in two-photon absorption of imidazopyridines derivatives

This work investigates the influence of different electron-withdrawing groups (Cl, Br, fluorobenzonitrile), on the two-photon absorption cross-section of six imidazo[4,5-b]pyridine derivatives. The two-photon absorption cross-section spectra were obtained by ultra-fast Z-scan technique from 470 nm up to 700 nm. The Sum-Over-States approach was applied to model the two-photon absorption spectra, using a three-level energy system. Photophysical properties, such as transition dipole moment, the difference of permanent dipole moments, and anisotropy coefficient were determined through the analysis of one-photon absorption spectra, solvatochromism, and fluorescence anisotropy, respectively. Besides, the excited state absorption spectra were measured through ultra-fast transient absorption, allowing the excited state lifetime and spectral position determination. Two-photon absorption cross-sections of about 160 GM were observed when two electron-withdrawing groups are linked to the imidazo[4,5-b]pyridine core, elucidating a path to achieve high optical nonlinearities in imidazopyridine derivatives. Furthermore, a increase in the two-photon cross-section was observed when chloride is linked at the C-6 position (90 GM) instead of the C-5 position (50 GM), which is related to the proximity of a higher excited state.

Re-mineralization potential, shear bond strength and hydration characteristics of experimentally prepared tri-calcium aluminate phase-modified glass ionomer cement on sound and caries-affected dentin (An in vitro/in vivo study)

BackgroundThis study aimed to in vivo and in vitro evaluate the remineralization potential and shear bond strength (SBS) of experimentally prepared tri-calcium aluminate (C3A)-modified glass ionomer cements on sound and artificial caries-affected dentin (CAD). A pure tricalcium aluminate (C3A) phase prepared via solid state reaction at elevated temperature from chemically pure calcium carbonate and alumina, to formulate ceramic composite of composition: 75% C3A, 15% CaSO4·2H2O and 10% Bi2O3. The influence of artificial saliva solution on the hydration characteristics and microstructure of the synthesized composite was investigated by X-ray diffraction (XRD) analysis, FTIR spectral analysis, pH determination and scanning electron microscope (SEM) in comparison with distilled water curing medium. Modified cements of C3A glass ionomers (C3A-CGIC) were prepared by addition of the experimentally prepared C3A to the powder component of the conventical glass ionomer cement (CGIC). Five and 10 wt% of C3A- CGICs powder were prepared and compared to CGIC. Cements were applied in prepared class V cavities in rabbits’ teeth either to sound or artificial CAD. All rabbits were killed after 15 days, and then, Ca and P wt% were evaluated at the cement–dentin interface using Energy-Dispersive X-ray Analysis. Specimens for SBS evaluation were prepared for the tested cements bonded either to sound or artificial CAD, then tested using universal testing machine.ResultsThe XRD results indicate that there is an acceleration effect on the hydration reactions and decrease in the rate of conversion process of C3A phase composite due to the presence of free ions in saliva solution which was emphasized by the results of the IR spectral bands of the hydrated paste samples. The SEM micrographs showed a more-dense microstructure with large accumulations of aluminate hydrate crystals of samples cured under saliva solution. Results of the prepared C3A-CGICs showed that 10wt% C3A-GIC group had the highest statistically significant mean Ca, P wt% and SBS values on CAD compared to 5wt% C3A-GIC and CGIC.Conclusions10 wt% C3A-GIC has a remineralizing effect on artificial CAD under in vivo conditions, plus its improved bonding to dentin compared to CGIC. Thus, it might be promising restorative/base with advanced remineralization potential and adequate bond strength to both sound dentin and CAD.

Multijunction solar cell spectral response determination at radiation damage study

This paper discusses multijunction solar cells with optically coupled p-n junctions under radiation exposure photosensitivity spectral response study. It is shown that if the measurement technique does not consider the luminescent coupling and does not track the optical coupling degradation, then instead of a decrease (which is a natural response of a photoconverter to radiation damage), an abnormal increase in the narrow-bandgap photoresponse (receiving luminescent radiation) subcell due to radiation damage can be observed. Accordingly, with an increase in the irradiation dose, an increase in the subcell photocurrent forming a “negative” degradation dependence of MJ SC being used in space applications is recorded.

Spectral determination method and its application to γ-ray determination

ABSTRACT We propose a simple algorithmic method of spectral determination method (SDM) for γ-ray determination, which is based on the first principle that a γ-ray spectrum obtained for a sample is a linear superposition of individual spectra of the radioactive nuclides included in the sample. The SDM treats the whole spectrum including peaks and a continuum background due to Compton scattering and does not need the peak analysis, which has been most conventionally used so far. The SDM was demonstrated by using two separate detector setups with a NaI detector or a Ge detector. The first experiment utilized six mixed standard sources. The determination accuracy of the SDM has turned out to be reasonable as compared with that of the peak analysis. In the next experiment for standard samples of JSAC0731 and JSAC0785, both Ge and NaI results show that the deviation of the SDM results from the certified values is within reasonable uncertainties for 137C and 134Cs. The present study demonstrates that the SDM is a reliable γ-ray determination method with a simple procedure.

Absolute choline tissue concentration mapping for prostate cancer localization and characterization using 3D 1 H MRSI without water-signal suppression.

PurposeUntil now, 1H MRSI of the prostate has been performed with suppression of the large water signal to avoid distortions of metabolite signals. However, this signal can be used for absolute quantification and spectral corrections. We investigated the feasibility of water‐unsuppressed MRSI in patients with prostate cancer for water signal–mediated spectral quality improvement and determination of absolute tissue levels of choline.MethodsEight prostate cancer patients scheduled for radical prostatectomy underwent multi‐parametric MRI at 3 T, including 3D water‐unsuppressed semi‐LASER MRSI. A postprocessing algorithm was developed to remove the water signal and its artifacts and use the extracted water signal as intravoxel reference for phase and frequency correction of metabolite signals and for absolute metabolite quantification.ResultsWater‐unsuppressed MRSI with dedicated postprocessing produced water signal and artifact‐free MR spectra throughout the prostate. In all patients, the absolute choline tissue concentration was significantly higher in tumorous than in benign tissue areas (mean ± SD: 7.2 ± 1.4 vs 3.8 ± 0.7 mM), facilitating tumor localization by choline mapping. Tumor tissue levels of choline correlated better with the commonly used (choline + spermine + creatine)/citrate ratio (r = 0.78 ± 0.1) than that of citrate (r = 0.21 ± 0.06). The highest maximum choline concentrations occurred in high‐risk cancer foci.ConclusionThis report presents the first successful water‐unsuppressed MRSI of the whole prostate. The water signal enabled amelioration of spectral quality and absolute metabolite quantification. In this way, choline tissue levels were identified as tumor biomarker. Choline mapping may serve as a tool in prostate cancer localization and risk scoring in multi‐parametric MRI for diagnosis and biopsy procedures.

Complex Formation of Cefazolin with Ca2+ and Mg2+: Synthesis, DFT, Spectral and Antibacterial Determination

AbstractMg(II) and Ca(II) complexes with cefazolin were synthesized and investigated using elemental and atomic‐emission analysis, TGA, X‐ray diffraction, FT‐IR spectroscopy, 1H and 13CNMR, DFT calculations, and QTAIM analysis. The thermal behavior of these complexes was also studied. In the magnesium complex, two cefazolin ions are coordinated to the metal ion through the oxygen atoms of the lactam and carboxylate groups as a bidentate ligand. However, cefazolin chelated to the calcium ion through both oxygen atoms of the carboxylate groups and the lactam groups′ oxygen atoms as tridentate ligand. Sodium cefazolin and metal complexes were also screened for antibacterial activity against Staphylococcus aureus and Escherichia coli. The calcium complex exhibited higher antibacterial effects than the magnesium complex (5.2–7.7 % higher against S. aureus– and 15.4–27.3 % against E. coli), which is related to weaker binding of Ca, compared to Mg, with the oxygen atom of lactam group and, as a result, more free releasing of the lactam group in the solving process.

ProFit-1D-A 1D fitting software and open-source validation data sets.

Accurate and precise MRS fitting is crucial for metabolite concentration quantification of 1 H-MRS spectra. LCModel, a spectral fitting software, has shown to have certain limitations to perform advanced spectral fitting by previous literature. Herein, we propose an open-source spectral fitting algorithm with adaptive spectral baseline determination and more complex cost functions. The MRS spectra are characterized by several parameters, which reflect the environment of the contributing metabolites, properties of the acquisition sequence, or additional disturbances. Fitting parameters should accurately describe these parameters. Baselines are also a major contributor to MRS spectra, in which smoothness of the spline baselines used for fitting can be adjusted based on the properties of the spectra. Three different cost functions used for the minimization problem were also investigated. The newly developed ProFit-1D fitting algorithm is systematically evaluated for simulations of several types of possible in vivo parameter variations. Although accuracy and precision are tested with simulated spectra, spectra measured in vivo at 9.4T are used for testing precision using subsets of averages. ProFit-1D fitting results are also compared with LCModel. Both ProFit-1D and LCModel fitted the spectra well with induced parameter and baseline variations. ProFit-1D proved to be more accurate than LCModel for simulated spectra. However, LCModel showed a somewhat increased precision for some spectral simulations and for in vivo data. The open-source ProFit-1D fitting algorithm demonstrated high accuracy while maintaining precise metabolite concentration quantification. Finally, through the newly proposed cost functions, new ways to improve fitting were shown.

Estimation of Wear Resistance for Multilayer Coatings Obtained by Nitrogenchroming

This article deals with improving the wear resistance of multilayer coatings as a fundamental problem in metal surface treatment, strengthening elements of cutting tools, and ensuring the reliability of machine parts. It aims to evaluate the wear depth for multilayer coatings by the mass loss distribution in layers. The article’s primary purpose is to develop a mathematical method for assessing the value of wear for multilayer steel-based coatings. The study material is a multilayer coating applied to steel DIN C80W1. The research was performed using up-to-date laboratory equipment. Nitrogenchroming has been realized under overpressure in two successive stages: nitriding for 36 h at temperature 540 °C and chromizing during 4 h at temperature 1050 °C. The complex analysis included several options: X-ray phase analysis, local micro-X-ray spectral analysis, durometric analysis, and determination of wear resistance. These analyses showed that after nitrogenchroming, the three-layer protective coating from Cr23C6, Cr7C3, and Cr2N was formed on the steel surface. Spectral analysis indicated that the maximum amount of chromium 92.2% is in the first layer from Cr23C6. The maximum amount of carbon 8.9% characterizes the layer from Cr7C3. Nitrogen is concentrated mainly in the Cr2N layer, and its maximum amount is 9.4%. Additionally, it was determined that the minimum wear is typical for steel DIN C80W1 after nitrogenchroming. The weight loss of steel samples by 25 mg was obtained. This value differs by 3.6% from the results evaluated analytically using the developed mathematical model of wear of multilayer coatings after complex metallization of steel DIN C80W1. As a result, the impact of the loading mode on the wear intensity of steel was established. As the loading time increases, the friction coefficient of the coated samples decreases. Among the studied samples, plates from steel DIN C80W1 have the lowest friction coefficient after nitrogenchroming. Additionally, a linear dependence of the mass losses on the wearing time was obtained for carbide and nitride coatings. Finally, an increase in loading time leads to an increase in the wear intensity of steels after nitrogenchroming. The achieved scientific results are applicable in developing methods of chemical-thermal treatment, improving the wear resistance of multilayer coatings, and strengthening highly loaded machine parts and cutting tools.

Морфометрические показатели сетчатки у пациентов с эпиретинальным фиброзомcтракционным компонентом в ранний период оперативного лечения

The analysis of the morphometric of the retina in patients with epiretinalmembrane was carried out using spectral coherent optical tomography and determination of retinal photosensitivity in the early postoperative period. A decrease in retinal edema was revealed due to a decrease in the thickness of the inner layers of the neuroepithelium in patients with vitreoretinal pathology after surgical treatment. Keywords: epiretinal membrane, morphometric parameters of the retina, vitrectomy, membranopilling.

Studying Interfacial Dark Reactions of Glyoxal and Hydrogen Peroxide Using Vacuum Ultraviolet Single Photon Ionization Mass Spectrometry

Aqueous secondary organic aerosol (aqSOA) formation from volatile and semivolatile organic compounds at the air–liquid interface is considered as an important source of fine particles in the atmosphere. However, due to the lack of in situ detecting techniques, the detailed interfacial reaction mechanism and dynamics still remain uncertain. In this study, synchrotron-based vacuum ultraviolet single-photon ionization mass spectrometry (VUV SPI-MS) was coupled with the System for Analysis at the Liquid Vacuum Interface (SALVI) to investigate glyoxal dark oxidation products at the aqueous surface. Mass spectral analysis and determination of appearance energies (AEs) suggest that the main products of glyoxal dark interfacial aging are carboxylic acid related oligomers. Furthermore, the VUV SPI-MS results were compared and validated against those of in situ liquid time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reaction mechanisms of the dark glyoxal interfacial oxidation, obtained using two different approaches, indicate that differences in ionization and instrument operation principles could contribute to their abilities to detect different oligomers. Therefore, the mechanistic differences revealed between the VUV SPI-MS and ToF-SIMS indicate that more in situ and real-time techniques are needed to investigate the contribution of the air–liquid interfacial reactions leading to aqSOA formation.

Laplacian spectral determination of path-friendship graphs

A graph G is said to be determined by the spectrum of its Laplacian matrix (DLS) if every graph with the same spectrum is isomorphic to G. In some recent papers it is proved that the friendship graphs and starlike trees are DLS. If a friendship graph and a starlike tree are joined by merging their vertices of degree greater than two, then the resulting graph is called a path-friendship graph. In this paper, it is proved that the path-friendship graphs, a natural generalization of friendship graphs and starlike trees, are also DLS. Consequently, using these results we provide a solution for an open problem.

Rapid determination of trace Cu2+ by an in-syringe membrane SPE and membrane solid-phase spectral technique.

A new in-syringe membrane SPE and solid-phase visible spectral method was proposed for the rapid extraction and visible spectral determination of trace Cu2+. The chelation and membrane SPE can be accomplished in a syringe. The yellow Cu(DDTC)2 complex was separated using a polyethersulfone membrane from the sample solution. Then, the complex can be detected directly on the polyethersulfone membrane utilizing solid-phase visible absorbance spectra without elution. The proposed method simplified the experimental procedure and improved the sensitivity to the μg L-1 level. Furthermore, this method is environmentally friendly since it avoids the use of organic solvents. After the investigation of the influence of different variables on the membrane SPE procedure, water and blood plasma were analyzed to validate the proposed method. A LOD of 0.04 μg L-1 and recoveries of 96.0-103.7% confirmed that the present work can be applied for the determination of trace Cu2+ in water and blood plasma samples.