The effect of plasmon nanoparticles (NPs) on the fluorescence and phosphorescence intensity of organic dye molecules has been studied theoretically and experimentally. To calculate the luminescence intensity of a molecule in the presence of a plasmonic NP, a theoretical model is proposed that takes into account the nonradiative transfer of excitation energy from the molecule to the NP and the change in the rates of spontaneous emission of the molecule and light absorption by the molecule near the NP. Numerical estimations performed for the erythrosine molecule and the silver NP showed that the greatest increase in luminescence is observed at distances of 4-8 nm between the molecule and the NP surface. The changes in the luminescence spectra and the shortening of the lifetime of the erythrosine triplet state in polyvinyl alcohol films doped with silver NPs observed in the experiment are explained on the basis of the proposed model.

Ti_1–xSmxO_2–x/2 (x = 0.025, 0.05, and 0.1) solid solutions with anatase structure were synthesized by the precursor method and characterized by X-ray diffraction and scanning electron microscopy. Titanium glycolate Ti(OCH₂CH2O)₂, in which Ti was partially replaced by Sm, was used as a precursor. At room temperature upon 350 nm excitation, solid solutions Ti_1–xSmxO_2–x/2 exhibit intense reddish-orange luminescence. The luminescence properties of compounds were studied based on the f⁵ -intraconfigurational transitions of samarium. For Ti_1–xSmxO_2–x/2, the highest luminescence intensity is achieved at x = 0.05. The chromaticity coordinates and the correlated color temperature values are close to those that are typical for red phosphors.

A spectral model of luminescence of a two-component exciton-activated quantum dot (QD) - spheroidal plasmon nanoparticle (NP) in a homogeneous external magnetic field is constructed. The model is constructed in the approximation of the tensor of the dipole electric polarizability of the nanoparticle, taking into account the dissipation of the excitation energy in the nanoparticle. A tensor representation of the permittivity of a magnetized electron plasma of a metal responsible for the formation of electric field characteristics in a spheroid is used. It is established that with a change in the eccentricity of the spheroid, the luminescence spectrum of the system changes, reflecting, among other things, the effect of an external magnetic field on both the radiation and dissipative properties of the binary quantum dot -nanoparticle complex.

A formula is obtained for the absorption coefficient of intense terahertz radiation by free electrons in a semiconductor when the main mechanism of electron scattering is the spontaneous emission of polar optical phonons. It is shown that the absorption coefficient increases sharply when the average energy of electron oscillations in the terahertz field exceeds the energy of the optical phonon.

The possibility of measuring the degree of fixing (pinning force) of domain walls in cobalt nanowires by the NMR spin-echo method under the action of an additional magnetic video-pulse on a two-pulse echo is shown. This method can be used for NMR estimation of the pinning force of domain walls and the coercive force of cobalt nanowires in order to optimize their chemical synthesis in an external magnetic field for potential use in rare-earth-free permanent magnets, sensors, and other applications.

The crystallographic structure, elemental composition, and surface morphology of the cadmium sulfide (CdS) thin films chemically deposited at Т = 62 ± 1 о С on glass substrates from aqueous solution consisting of NH₄OH (25 %), 0.0096M CdSO₄, and 0.8M CS(NH₂)₂ have been studied. The characteristics of these films have been obtained by the scanning electron microscopy, studies of the phase and elemental composition, as well as Raman spectra. It is shown that the selected solution’s composition and deposition modes allow to synthesize CdS films with stoichiometric composition, consisting of nanocrystals of hexagonal modification suitable for solar cells applications.

A spectral model of luminescence of a two-component exciton-activated quantum dot (QD)-spheroidal plasmon nanoparticle (NP) in a homogeneous external magnetic field is constructed. The model is constructed in the approximation of the tensor of the dipole electric polarizability of the nanoparticle, taking into account the dissipation of the excitation energy in the NP. A tensor representation of the permittivity of a magnetized electron plasma of a metal responsible for the formation of electric field characteristics in a spheroid is used. It is established that with a change in the eccentricity of the spheroid, the luminescence spectrum of the system changes, reflecting, among other things, the effect of an external magnetic field on both the radiation and dissipative properties of the binary QD-NP complex.

The processing method of the Mössbauer spectra of multicomponent single-phase disordered solid solutions by using the extended mathematical model is proposed. The method makes it possible to detect local distortions of the body-centered cell structure and symmetry of the environment of a resonant atom, arising from differences in the properties of atoms of the mixed components. Using the examples of processing the Mössbauer spectra of single-phase disordered solid solutions of the systems Fe₇₅Si₁₅Al₁₀, Fe₇₅Si₁₅Ge₁₀, Fe₇₅Sn₁₅Ge₁₀, the significance of the extended mathematical model for obtaining reliable information and, accordingly, reliable interpretation of the results of a spectroscopic experiment is shown.

Using the method of differential absorption photometry and the technology of sequential saturating light pulses of modulated frequency, the kinetics of P700 oxidation/reduction in the leaves of the upper tier of tomato plants was studied under the influence of elevated temperature (40°C, 3 h) and infection with Fusarium oxysporum and their conjugated action. Thermal exposure reduced the level of P700 oxidation, the quantum yield of photochemical reactions of photosystem I (PSI) and increased the non-photochemical energy dissipation on the acceptor side of PSI. At the same time, in heat-treated plants, the contribution of the electron flow catalyzed by ferredoxin-plastoquinone reductase (FQR) decreased and the proportion of cyclic electron transport dependent on the NADH dehydrogenase-like complex (NDH) increased. When plants were infected with the pathogenic fungus Fusarium oxysporum, a decrease in the quantum yield of photochemical reactions of PSI and a significant increase in non-photochemical energy dissipation on the acceptor side of PSI were observed. The conjugated effect of elevated temperature and Fusarium oxysporum enhanced the suppressive effect of both stress factors on the photoinduced oxidation of P700 and activated non-photochemical energy dissipation on both the acceptor and donor sides of PSI. At the same time, the suppression of linear and FQR-dependent cyclic electron flows induced by Fusarium wilt and elevated temperature was compensated by the activation of NDH-dependent electron transport.

The studies on the interaction of intercalators methylene blue (MB) and ethidium bromide (EtBr) with synthetic single-stranded (ss-) polynucleotides poly(rA) and poly(rU) as well as with the formed doublestranded (ds-) poly(rA)-poly(rU), resulted from their hybridization, have been carried out at the ionic strength at the solution of 0.04 mol, in interval of r = phosphate/ligand ratio 0 £ r £ 10. The absorption spectra of the complexes of these ligands with the mentioned polynucleotides were obtained and on the basis of changes of these absorption spectra the binding isotherms in Scatchard’s coordinates were constructed. It was revealed that MB interacts with both poly(rA) and ds-poly(rA)-poly(rU) cooperatively, while in the case of poly(rU), cooperativity is not found out. Coopeartivity is absent at the interaction of EtBr with ssand ds-polynucleotides as well. From the adsorption isotherms, the binding parameters of these ligands with the mentioned polynucleotides – values of association constant K and number of base pairs per binding site n, as well as cooperativity factor value at the interaction of MB with poly(rA) and ds-poly(rA)-poly(rU) were determined. Both ligands were revealed to bind to polynucleotides at least by two modes, though, MB shows much higher affinity to poly(rA), while EtBr – to ds-poly(rA)-poly(rU).

The main physiological and biochemical characteristics and elemental composition of three lichens species of the genus Hypogymnia (Nyl.) Nyl. in one habitat were studied using the methods of spectroscopy. The model species by decreasing degree of anthropotolerance rate in the following order: Hypogymnia physodes (L.) Nyl.®H. tubulosa (Schaer.) Hav.®H. vittata (Ach.) Parrique. The contents of chlorophylls a and b, phenolic compounds, pheophytinization quotient and antiradical activity were determined by a spectrophotometric method. The antioxidant activity was determined by an amperometric method. The values of physiological and biochemical parameters for each of the three species correspond to the values for the background ecotopes. In species with low degree of anthropotolerance, the values of these parameters and the integrity of the system of correlation relationships between parameters are lower. Using the method of ICP-AES, 23 elements were found in the thalli of model species. Among them are macro- and microelements, heavy metals and metalloids. The maximum concentrations of most elements were found in H. vittata, while the minimum concentrations were found in H. physodes. The analysis of interaction between physiological and biochemical characteristics and the content of elements indicates the presence of a complex system of correlation relationships in each species. Differences in this system of relationships may be due to the specific composition of secondary metabolites, which determine the features of adaptive reactions. The use of various methods of optical spectroscopy allowed to evaluate not only the functional specificity of the studied species, but also its connection with the level of their anthropotolerance. Low resistance to anthropogenic influences is combined with lower coordination of physiological and biochemical characteristics and low integrity of the system of correlational relationships. In the most vulnerable species of H. vittata, minimal values of the main functional parameters, their lesser correlation with the elemental composition and higher concentrations of some toxic elements were found. For bioindication and ecological physiology of lichen, it is crucial to use a complex analysis of physiological and biochemical characteristics and elemental composition by application of various spectral methods.

Effects of technogenic hydrocarbons (benzоpyrene, butyl acetate and o-xylene) on the state of stress-sensitive photosystem II in the leaves of drooping birch seedlings, small-leaved linden, maple holly and poplar pyramidal were assessed by pulse-amplitude modulated fluorimetry (РАМ). The degree of response to toxication, though being similar for toxic agents of different nature, depended on the previous stress in plants. Indeed, birch seedlings that had undergone natural stress reacted weaker to chemical one. The leaves of poplar showed the highest response to toxicity combined with rapid adaptability. The most sensitive parameter was the coefficient of non-photochemical fluorescence quenching qN, which increased after treatment with hydrocarbons by 2-5 times in seedlings of different species. The nonradiative dissipation of excitation energy is probably the main mechanism for protecting photosynthetic membranes under chemical stress.

An approach adequate to natural processes for testing the antioxidant properties of biological material based on spectral changes in hemoproteins during the formation of a complex with peroxidized phosphatidylcholine and its derivatives, recorded using difference spectroscopy, has been demonstrated. This method can be used in clinical and biochemical studies, as well as to develop methods for diagnosing the protective ability of the human organism to oxidative stress and predicting its ability to recover from diseases of varying severity.

The development of an operational non-invasive technique for assessing the state of the microcirculatory blood vessels of the cardiovascular system is a promising direction in creating equipment for the differential diagnosis of the causes of vascular dystonia and arterial hypertension. The possibilities of diffuse reflectance spectroscopy in determining the main parameters of the microvasculature are analyzed. A computational model for the formation of the spectral-temporal profile of local diffuse reflection of light radiation by pulsating blood-filled tissue is proposed, based on the diffusion approximation of radiation transfer in scattering media and simplified analytical expressions that describe the relationship between the shape of the photoplethysmogram and blood pressure. The structural features of the microcirculatory bed and the influence of the parameters of the arterial vessels of the pulsating section of this bed on systolic and diastolic blood pressure have been analyzed. It has been shown that taking into account the relative resistance to blood flow of different sections of the bloodstream and using a normalized photoplethysmogram to calculate intraluminal blood pressure in arterioles allows us to obtain an expression for calculating the coefficient of stretching of arteriole walls in the annular direction. A technique for recording spectraltemporal profiles of diffuse reflection and their modeling, as well as forming the corresponding residual function and searching for its minimum, is considered. The results of modeling the process of determining the parameters of the microvasculature taking into account equipment noise are presented. The results obtained confirm the possibility of creating a complex based on a miniature spectrophotometer, pulse oximeter and pulse wave velocity sensors, which is intended for prompt non-invasive assessment of both the stiffness of the main arterial vessels and small arterial vessels of the microvasculature.

Methodological aspects of creating a 3D lidar based on recording and processing of 2D intensity distributions of time-truncated realizations of reflected light fields are considered. The advantages of the proposed method in comparison with ToF technology “Range gated imagers” are shown: an increase in the range tenfold with the same power of probing radiation; the possibility of implementing the method on a publicly available element base without the use of specialized ToF processors.

The issues related to the possibility of recognizing opaque materials of remote objects using the pulsed laser photothermal radiometry with long-term pulsed exposure are considered. Theoretical calculations of the range of recognition of materials with laser activation of their surface are given. The calculation results indicate a significant influence of thermal parameters on the recognition range. It has been experimentally shown that there is a decrease in the range by about an order of magnitude if the material of the search object has a large thermal inertia (metals), compared with a material with a small thermal inertia (polycarbonate, rubber), which provides a sufficient probability for their difference. At the same time, the condition of strong surface absorption must be fulfilled at the wavelength of the laser radiation. For synthetic polymer products, CO₂ laser satisfies these considerations to the greatest extent. The influence of wind load on the temperature of the laser spot on the object is one of the key ones in the proposed method. The paper suggests a way to minimize this influence and even eliminate it almost completely. Issues related to the possibility of increasing the recognition range are discussed.

The application of sonoluminescent spectroscopy for determining the content of Na, K, Mg, and Ca in mineral waters is considered. A technique for preparing mineral water samples for spectral analysis and recording analytical luminescence spectra of these samples is described. For the first time, with a spectral resolution of Δλ = 1 nm, the spectra of a moving single-bubble sonoluminescence (m-SBSL) were obtained for colloidal suspensions in dodecane of SiO₂ nanoparticles (<50 nm) saturated with metal ions by adsorption from “Essentuki № 4”, “Essentuki № 17”, “Ash-tau”, “Rychal-su”, “Borjomi”, “Mtabi”. In these spectra, atomic and ionic lines of metals that are part of mineral water salts are identified: Na, K, Mg, Mg⁺, Ca, Ca⁺. Using artificial mineral water samples containing a known amount of metals in the form of Na, K, Mg, and Ca chlorides, the m-SBSL spectra of modeling samples of nanoparticle suspensions were obtained. The concentration dependences of these metal analytical lines intensities in these spectra are plotted at the wavelengths of their maximum emission: Na 589 nm, K 766 nm, Mg 518 nm, Ca⁺ 393 nm. The possible effect of the anions common in mineral waters Cl^–, CO₃^2–, SO₄^2– on the intensity of Na and K lines was considered separately, which confirmed the insignificance of this effect when varying anions in the composition of the salts used for modeling. Based on the obtained data, the content of metals in the sample of mineral water “Mtabi” was estimated: [Na]=7.3 × 10^–3 M, [K]=5.1 × 10^–3 M, [Ca]=1.9 × 10^–3 M, [Mg]=1.7 × 10^–3 M.

The features of degenerate four-wave mixing (DFWM) in a nematic liquid-crystal cell with photoconductive orienting layers are studied. To establish the vector diagram of the interaction of waves, a method was used according to which three plane waves at angles to each other are incident on the nonlinear medium. The probe wave interferes with two forward-pump waves, which, after passing through the cell, are reflected backward by two mirrors. A vector model is proposed that is in good agreement with the experimental results obtained. Its main difference from the standard DFWM diagram is that the vector of the refractive index grating, on which the wavefront is effectively conjugated in the dynamic photorefractivity mode, is at an angle to the vector of the optical interference grating. The experiment in the dynamic photorefractive mode demonstrated good correction of spherical and astigmatic aberrations, equivalent to the action of a lens with a focal length of less than 10 cm.

In this paper, we received equations determining the position of maximum I_max of the Fourier transformation of the Bessel–Gaussian beam (BGB), and its dependence on the topological charge is substantiated. It is found that Imax depends on the angle of the cone and the parameters of the Gaussian beam. Meanwhile, with a decrease in the cone angle (hence, an increase in the diffraction-free region), the distance between the maxima of the intensity distributions in the focal plane of the lens, corresponding to different values of the topological charge, increases. An expression for the position of the gravity center of the BGB Fourier image is found and it is shown that it also depends on the cone angle γ and the size of the Gaussian beam waist w₀. As the product γ w₀ increases, the displacement of the BGB gravity center with respect to the radius R of the annular Fourier spectrum decreases. The results obtained show the impossibility of forming perfect vortexes with the help of BGB. In this case, the degree of their “imperfection”, determined by the deviation of the maximum intensity distribution in the focal plane of the lens from the parameter R, which specifies the radius of the ring of the Fourier image of the Bessel beam, turns out to be greater for beams with a larger diffraction-free region.

Jadeite is a sought-after jade mineral that is often imitated using natural and artificial materials. A jadeite imitation that is convincing to the naked eye is investigated. The imitation is yellowish green and white, subtranslucent, and exhibits a vitreous luster. Standard gemological testing and spectral characterization revealed the composition to be wollastonite and soda–lime–alumina–silica glass. The wollastonite was added during the sintering process, making it different to wollastonite glasses prepared by devitrification in earlier reports. The findings demonstrated that shifted excitation Raman difference spectroscopy is a cost-effective, efficient, and nondestructive technique for identifying gemstones and their imitations, particularly those showing strong fluorescence.

The synthesis and luminescence analysis of Tb3+-activated phosphors were reported. Y₂SiO₅ phosphors were synthesized by a modified solid-state reaction method with a variable doping concentration of Tb³⁺ ion (0.5–2.5 mol.%). As synthesized, the phosphors were characterized by X-ray diffraction (XRD) analysis. The XRD pattern confirmed the monoclinic structure of the prepared phosphor. Scanning electron microscopy and High-Resolution Transmission Electron Microscopy (HRTEM) studies revealed nearly uniform particle size distribution in the prepared phosphors. The photoluminescence excitation spectra of the Y₂SiO₅:Tb3+ (0.5–2.5 mol.%) phosphor displayed one broad, intense peak at 258–277 nm. When excited at the 258 nm wavelength, the phosphors showed emission peaks at 553 nm (⁵D4®⁷F5), 544 nm (⁵D4®⁷F5) and 489 nm (⁵D4®⁷F6). The 1931 CIE (x,y) chromaticity coordinates showed the distribution of the spectral region calculated from the photoluminescence emission spectra. The values of x = 0.25 and y = 0.46 were very close to light green emission. Therefore, the prepared phosphor is very useful for light-emitting diode (green component) applications. 

Today, magnetic field inhomogeneity in high-field NMR machines is minimized by proper shimming of the machine and extensive dilution of the sample with deuteron solvents. Hence, the line width (LW) measurements of the NMR peaks are reliable for NMR studies. This study is aimed at examining the relationship between the crude oil properties and the LW values of the CH₂ and CH₃ peaks and the relationship between the LW of water in crude oil and the percentage of water. A set of 22 mixtures was prepared by adding 0.02 mL of each crude oil to each 0.98 mL of CDCl₃. A suitable NMR spectrum, including the water peaks of the mixtures, was obtained with a spectrometer operating at 400 MHz. Paraffinic CH₂ and CH₃ peak LWs vary from well to well. Paraffinic CH₃ LW decreases nearly linearly with American Petroleum Institute gravity. In addition, the LW of the water peak at 4.75 ppm is strongly related to the percentage of water in crude oil. The mixtures used in this study provide the appropriate NMR peaks for CH₂, CH₃, and water in crude oil. NMR peaks of water in crude oil were displayed for the first time in the high field. Some of the previous results obtained in the low-NMR field were found. Therefore, this study suggests an additional approach for high-field NMR studies in petroleum chemistry.

The extended cavity diode lasers were stabilized using the first and third derivatives obtained by the frequency modulation method from the hyperfine resonances of the ⁸⁷Rb D2 transition line. The frequency stability values were measured as 3.1´10^–12, 5.6´10^–13, and 1.9´10^–12 for integration times of 1, 10², and 10⁴ s, respectively, using the first derivatives of F=1→F¢=1 and F=1→F¢=2 resonances. By use of the third derivatives of F=2→F¢=1,3 and F=2→F¢=2,3 cross-over resonances, 4.0´10^–12 − 1 s, 5.7´10^–13 − 10² s, 9.3´10^–13 − 10⁴ s frequency stability values were obtained. These values compared with the results of the previous study obtained by the Zeeman modulation method.

Focusing on the problem of unclear ray-traced spots and their distribution rules in the design process of the Herriott cell, first, the characteristics of long-optical-path gas absorption cells were analyzed, and the calculation method of basic cavity length and the effective optical path of Herriott gas absorber cells were studied. Second, according to the transmission characteristics of geometric optics, a physical model of light transmission in Herriott cells was established via the LightTools software. Finally, simulation analysis was performed on Herriott cells with 5- and 14.4-m optical paths separately, determining the quantitative relationship between d/f and the number of spots reflected on the concave mirror, and optimizing the effective optical path and output laser energy of the Herriott cells. Through research analysis, the sizes and distribution positions of concave mirror spots in the Herriott cells were identified, as well as the factors affecting the number of reflections. It was also found that the number of reflected spots gradually decreases as d/f increases, revealing the light-tracing results and its spot distribution rule on the mirror surface, as well as verifying the accuracy of the theory. The findings of this study provide a basis for the optical path system design and optimization for Herriott cells with different optical path lengths.

This paper presents a theoretical investigation of the formation of quadruple Gaussian breather solitons in diffraction-managed optical media. The optical nonlinearity of the medium has been modeled by cubicquintic nonlinearity. Physical insight into the propagation dynamics of the laser beam semi-analytical solution of the wave equation for the laser beam has been obtained by using the moment theory approach in W.K.B. approximation. Emphasis is put on investigating evolutions of transverse dimensions and axial phase of the optical beam. The existence of stable spatial optical solitons resulting as a consequence of dynamic balance of diffraction broadening by Kerr effect induced self-focusing also has been investigated.

Employment of an external magnetic field on a frequency-chirped cos² laser pulse envelope for effective electron acceleration is studied. After the electron interacts with the laser pulse, the frequency chirp influences the electron dynamics, betatron resonance, and energy gain of the electron, ensuring effective acceleration of the electron with significant energy gain in the order of GeV. If a suitable external magnetic field is applied, an electron can gain energy and retain the same energy significantly. In this research, we employed the cos2 laser pulse envelope to examine the impact of the laser pulse envelope on the investigation of electron acceleration in a vacuum. The front of the tested envelopes had received an axial injection of electrons. In all calculations, it is assumed that the front end of each pulse met the electron at time t = 0 at the position of origin. The relativistic Newton–Lorentz equations of electron motion in the field of the laser pulse have been solved analytically and numerically.

We investigated the feasibility of using surface-enhanced Raman scattering (SERS) technology combined with the AdaBoost algorithm to rapidly discriminate cervical cancer patients from hysteromyoma patients. Using Au colloids as the SERS active substrate, we recorded Raman signal measurements on serum RNA samples obtained from 35 patients diagnosed with cervical cancer and 30 patients diagnosed with hysteromyoma. Analysis of RNA SERS spectra using principal component analysis, then three principal components (PC2, PC11, and PC24) with significant differences were chosen using the independent samples t-test (p < 0.05). The distinctive peak intensities of the relevant substance, measured at 448, 519, 698, 1003, and 1076 cm–1 , were found to be correlated with the substance's alterations during the carcinogenesis process. The ideal AdaBoost classification model was developed by fine-tuning its parameters. The model showcased an impressive accuracy of 96.92%, exhibiting a high sensitivity of 94.28% and an exceptional specificity of 100%, as reported in the results. Compared to the linear discriminant analysis, support vector machine models, the effectiveness of classification greatly improved. The current findings indicate that serum SERS technology, combined with the AdaBoost algorithm, is anticipated to be developed into a potent screening tool for cervical cancer.

Different manufacturers do not produce the same quality of children’s Ca-Fe-Zn oral liquid due to different production materials and processes. To improve the phenomenon of counterfeit and imitation oral liquid on the market and effectively monitor its quality, laser-induced breakdown spectroscopy (LIBS) fingerprinting with sample preparation methods can provide a tool for real-time and rapid detection of oral liquids. The sample preparation methods include filter paper adsorption (FPA), filter paper adsorption with elemental Cu (FPA with Cu), adding dropwise to glass slides (ADS), adding dropwise to glass slides with elemental Cu (ADS with Cu), and gel preparation (GP). This work collected LIBS spectrum of oral liquids from eight manufacturers. The model for eXtreme Gradient Boosting (XGBoost) was constructed for classifying oral liquids based on five sample preparation methods. The accuracy was 91.25, 94.17, 55.42, 91.25, and 91.29%, respectively. The results show that the FPA method is more straightforward, efficient, and less affected by the specificity of the color of the sample. Both ADS and GP are susceptible to the color characteristics of the sample and are not well suited to the direct detection of transparent liquids. This work demonstrated that oral liquids could be discriminated by analyzing LIBS spectrum combined with the XGBoost model. Additionally, sample preparation, like the simple FPA method, can improve the accuracy of LIBS classification.

Hydrocortisone is a glucocorticoid-type hormone produced naturally by the organism, such that it maintains the body functional during physical or mental stress episodes. The present work focuses on the UV-Vis spectrophotometric assessment of the chemical stability of hydrocortisone in an aqueous medium during the time of analysis, determination of its acidity constants through a robust methodology that involves the usage of SQUAD software and validation of an analytical method to determine hydrocortisone by means of UV-Vis spectrophotometry, in pharmaceuticals. The acidity constant was determined as pK_a 11.45 ± 0.02 (298 K), and the molar absorptivity coefficients and the molar absorptivity coefficients of the species involved in this acidity equilibrium were also determined as a function of the wavelength. The analytical method developed attained detection and quantification limits of 386 ± 3 and 1280 ± 10 nM, respectively, whereas the validation allows reliable quantification of hydrocortisone in pharmaceuticals.

The primary, bioactive component of Cordyceps militaris, known as cordycepin (3'-deoxyadenosine), has been utilized extensively as a traditional medicinal ingredient and a nutritious diet in Asian nations. To determine the amount of cordycepin in the C. militaris, high-performance liquid chromatography (HPLC) is shown to be an effective, sensitive, and straightforward analytical technique. Other methods for estimating cordycepin include near infrared spectroscopy and capillary electrophoresis–mass spectrometry. The UV-Vis spectroscopy approach was used to quantify cordycepin, and the results were statistically confirmed and compared with an HPLC method. For linearity, repeatability, precision, reproducibility, limit of detection and limit of quantification, the method was verified. The established approach can be utilized for routine, quality control analysis of cordycepin, as it is easy to use, sensitive, accurate, precise, repeatable, and most importantly, cost-effective.

The Cu(II) was found using a quick and uncomplicated procedure that involved reacting it with a freshly synthesized ligand to create an orange complex that had an absorbance peak of 481.5 nm in an acidic solution. The best conditions for the formation of the complex were studied from the concentration of the ligand, medium, the effect of the addition sequence, the effect of temperature, and the time of complex formation. The results obtained are scatter plot extending from 0.1–9 ppm and a linear range from 0.1–7 ppm. Relative standard deviation (RSD%) for n = 8 is less than 0.5, recovery % (R%) within acceptable values, correlation coefficient (r) equal 0.9986, coefficient of determination (r²) equal to 0.9973, and percentage capital R-squared explained variation as a percentage/total variation (R²%) equal to 99.73. The method has been successfully applied for the estimation of Cu(II) ions without the influence of other interfering ions, and it can be applied to estimate Cu(II) in any sample.

Semiconducting nanostructured materials are preferred for optoelectronic devices due to their variable optical and electrical properties. Cadmium sulfide (CdS) thin films, due to its direct band gap, are widely used in solar cells, photodetectors, photosensors, etc. This work analyzes the effect of thermal annealing on the optical and structural properties of CdS thin films. CdS thin films are synthesized by a sol-gel spin coating technique while maintaining a constant pH level of the precursor solution. CdS thin films were annealed at 400, 450, and 500o C for 30, 60, and 90 min, respectively. The transmittance of the films varied from 60–89% in the visible region as evident from the UV analysis. The optical band gap lay in the range of 2.43–2.47 eV. The XRD and Raman analysis results reveal that the crystallinity of the CdS thin film increased with the increasing annealing temperature and time of annealing.

The quality of pork is largely influenced by moisture, fat, and protein. In the meat industry, the establishment of a fast and accurate prediction system is always welcomed. Near infrared spectroscopy (NIRS) can satisfy the requirements of the evaluation. An automatic routine based on support vector regression (SVR), a backpropagation neural network (BPNN), and principal component analysis-backpropagation neural network (PCA-BPNN) was developed to predict three components of pork using 16 combinations of pretreatment (convolution function-based moving average, detrending based on the standard normal variate, and multiplicative scatter correction). Model comparisons were implemented to evaluate the influence of pretreatment and calibration models on the prediction ability of models. The correction method and smoothing methods can significantly reduce the model prediction error. Most of the SVR models have high prediction accuracy and are suitable for predicting moisture and protein. The BPNN and PCA-BPNN are more suitable for dealing with nonlinearity between fat and NIR observations.