The influence of the dielectric surface on Rb atoms of D₂-line at nanometer distances has been experimentally studied. The use of a nanocell filled with atomic rubidium with a wedge-shaped gap, has made it possible to study the influence of the distance of atoms in the range of 45–150 nm from the surface of a window made of commercial sapphire. At distances from the sapphire surface of less than 130 nm, due to the van der Waals interaction, ⁸⁵Rb and ⁸⁷Rb atomic transitions are strongly broadened, and their frequency shifts are carried out to the low-frequency spectrum region. The use of the method of the second derivative of the nanocell absorption spectra has made it possible to measure the van der Waals interaction coefficient C₃ = 1.8±0.3 kHz ∙ μm³ for Rb D₂-line. It is shown that at a nanocell thickness of 65±5 nm, an additional red shift occurs with atoms density increase, due to the dipole-dipole interaction of Rb atoms. The results can be used in the development of miniature submicron devices.

Two variants of magnesium alloys surface modification have been considered to increase the intensity of spectral lines. The use of gold nanoparticles for the alloys’ components leads to 1.5—2-times increase of signal-to-noise ratio. The use of a dye leads to the decrease of this ratio. It has been shown that the efficiency of laser radiation absorption on the surface does not influence substantially the ablation when metals are affected with nanosecond pulses. Moreover, the accumulation of signal from three pulses with surface cleaning is enough to overcome the effect from the use of nanoparticles.

The study of the binding of thiazine dye methylene blue (MB) with single-stranded (ss-) synthetic polyribonucleotides poly(rA) and poly(rU) has been carried out with the methods of absorption spectroscopy and UV-melting. It has been revealed that the binding mechanisms of MB to poly(rA) significantly differs from that one of MB binding to poly(rU). The obtained data indicate that the main binding mode of MB to ss-poly(rA) corresponds to semi-intercalation, while at the binding to poly(rU) — electrostatic binding. MB has been also found out to contribute to the formation of hybrid duplex poly(rA)-poly(rU).

Sample preparation methods have been developed and adapted for using gold nanoparticles in the qualitative analysis of paint layers composition with the surface-enhanced Raman scattering (SERS) method. The use of plasmonic nanoparticles for the SERS analysis of art materials in real objects of painting can significantly reduce the luminescent background caused by the presence of organic binders of the paint layer, and, along with multiple amplification of the chromophore Raman line`s intensities, leads to an increase in the signal-to-noise ratio. The techniques are successfully tested on the paint layers of 12 easel paintings of the XVI—XIX centuries in close cooperation with the museums of the Republic of Belarus, can be systematically used in art history expertise for identification of the composition of paints and attribution of cultural heritage objects.

The role of molecular structure in the formation of bathochromic band shift of S₀→S₁ transition for the family of N-substituted porphine derivatives has been studied. The molecular conformation of the porphine, four its N-substituted derivatives and two model porphine molecules with selected fixed angles and bond lengths in the macrocycle has been optimized, the energies of molecular orbitals have been determined, and electronic absorption spectra have been calculated with quantum chemistry methods. It has been found that N-substitution leads to a significant pyramidalization of the nitrogen atom, and the degree of hybridization λ² of the nitrogen atom depends on the volume of the N-substituent and reaches the value of λ² = 2.729 in the H(N-CCl₃)P porphyrin molecule. It has been established that the factor that determines the energy of the long-wavelength S₀→S₁ transition is the degree of hybridization of λ² nitrogen atom, since upon pyramidalization of the nitrogen atom the conjugation along the inner C_a–N–C_a fragment of the pyrrole ring decreases while simultaneously strengthening of π-conjugation via outer C_a–C_b–C_b–C_a fragment, which leads to increase in the size of the conjugated π-system. The tilt of the N-substituted pyrrole ring relative to the macrocycle mean plane and the electron-donating/electron-withdrawing properties of the N-substituents do not directly affect the bathochromic shift of the S₀→S₁ transition.

The results of studies of radiation-chemical effects on the structural-group composition of a model mixture of n-hexane–n-hexene in the ratios 95/5, 90/10, 80/20, 60/40% under static conditions are presented. Laboratory studies were performed on a source of gamma radiation Co⁶⁰ at a dose rate of P = 0.076 Gy/s in the range of absorbed doses D = 27–78 kGy. Density, viscosity, and iodine numbers of n-hexane–n-hexene mixtures were determined immediately after irradiation, and 1, 2, and 7 months after irradiation at different absorbed doses to observe post-irradiation effects. It can be seen from the IR spectra that in mixtures with a low content of n-hexene (5–10 %), the initial direction of radiation-chemical processes consists of dehydrogenation and the formation of olefins. In mixtures rich in n-hexene (20–40 %), both processes – olefin formation and polymerization – occur at the same time during gamma radiolysis. Irradiation of n-alkenes is accompanied by polymerization processes proceeding in a chain mechanism. After irradiation of the mixtures, the density and viscosity increase, and the iodine number decreases. The rate of polymerization during radiolysis of n-hexane–n-hexene mixtures depends on the concentration of olefin in the system and the absorbed dose. At doses above 45 kGy, polymerization becomes the dominant process in systems containing more than 20 % olefins.

The ¹³³Cs NMR method was applied to study the structural characteristics and properties of perovskites at the atomic level in this work. CsBi_xPb_1–xBr₃ perovskites doped with bismuth at concentrations of 0.0059, 0.0072, 0.0120 were used as the studied samples. For applications in optics and photonics, the importance of high quality of materials was noted. The ¹³³Cs NMR method showed a significant sensitivity for studying the manifestations of these concentrations of bismuth, which affect the stability of perovskites and their dynamic parameters.

Comparative studies of charge carrier concentration (n) and relative strain (e) in graphene synthesized with chemical vapor deposition and transferred to the surface of SiO₂/Si substrate using two different frames, polymethylmethacrylate (PMMA) and paraffin, followed by complex processing, were carried out. The correlation method for determining the positions of Raman active modes was implemented for the analysis. It was established that in the case of paraffin, the concentration of charge carriers in graphene was initially lower than for PMMA. Further liquid phase and heat treatment used to remove the paraffin frame led to an increase in n up to 1.2×10¹³ cm^–2. For graphene samples transferred using a PMMA frame, no clear trend in the change in n was observed, regardless of the types of processing. At the same time, the spread of e values for graphene transferred with paraffin followed by liquid phase and heat treatment in vacuum was greater than for graphene transferred with PMMA and passed through a similar treatment, –0.01875 — –0.1488% and –0.04375 — –0.0875%, respectively. The results obtained during the study made it possible to establish that, in addition to the transfer frame material itself, a combination of processing methods had a decisive impact on the quality of graphene. Optimization of these parameters made it possible to increase the efficiency of the graphene transfer technique with a simultaneous improvement in the performance characteristics of graphene nanoelectronic devices.

The scattering problem for dimer consisting of a carbon nanotube (CNT) coated with a thick gold layer everywhere except for a narrow central region is solved in the far infrared range by numerical methods. A nanotube in such a dimer is a low-conductive channel that slows down the flow of charges between two parts of the highly conductive gold coating. Charge transfer plasmon resonance arises at a frequency of 21 THz in the spectrum of the absorption cross section of a dimer with a length of 285 nm and a transverse size of 20 nm. The resonance width is determined mostly by the electron relaxation time in CNTs. It has been shown that the resonant frequency decreases and the absorption cross section at the resonant frequency increases with an increase in the transverse and longitudinal dimensions of the dimer. The presence of a contact resistance between the CNT and the gold layer leads to a shift of the resonant frequency to the low-frequency region and a decrease in the intensity of the absorption peak. The possibility of varying the CNT conductivity by means of electrostatic doping makes it possible to use such dimers as building blocks for metamaterials with controlled resonant properties in the far infrared range.

The gradient component of the light pressure force acting on a spherical dielectric nanoparticle located in an interference field formed by the superposition of oncoming laser beams is studied in detail. A theoretical analysis of the qualitative behavior of solutions to the basic dynamics equation for the motion of a transparent spherical nanoparticle in a spatially modulated laser beam under the action of a gradient force is carried out. It has been experimentally shown that forces capable of driving nanoscale particles in liquid media arise in the interference field of two plane counter-electromagnetic waves. The experimental results agree with the theoretical results.

We have studied the fluorescence of winter and summer furs of the ermine (Mustela erminea) taken from the dorsal and ventral parts of the animal's body. Furs have been irradiated with radiation at wavelengths of λ_exc = 270, 300, 365, 395, and 410 nm. We have found that the ventral part of the ermine fur fluoresces brighter compared to the fur of the dorsal part. It has been shown that the fluorescence spectra upon excitation at wavelengths of λ_exc = 270 and 300 nm are predominantly two-peak. We have detected that the single-peak fluorescence spectra of winter and summer furs obtained upon excitation at wavelengths of λ_exc =365, 395, and 410 nm differ markedly from each other in the position of the peak and the line width. A difference has also been found in the fluorescence spectra of the dorsal and ventral parts of the fur from each other. The results can be used to identify ermine skins in collections and items in the absence of other features.

The spectral-kinetic characteristics of the brown coal glow when exposed to samples by laser pulses (1064 nm, 14 ns, 1 GW/cm²) in the air at atmospheric pressure and in the vacuum at pressure of 10^–2 Torr have been studied. It has been shown that during the action of laser pulses, a vapor plasma torch is observed over the samples in vacuum, and the glow lines of ionized carbon and hydrogen atoms are evolved. At atmospheric pressure CO flame glow dominates in the spectra. After laser exposure, rotational-vibrational glow of H₂O and thermal glow of carbon particles are distinguished in the spectra. In the air at atmospheric pressure in time interval of 0.2–1.0 ms, when exposed to laser pulses of W = 1 GW/cm², a nonvolatile residue of coal particles is inflamed with the departure of incandescent carbon particles with temperature of about 2500 K.

In order to monitor the level of environmental safety, the content of heavy metals in the soil cover of Bishkek was measured. To study test samples containing heavy metals, the method of atomic emission spectral analysis was used. The quantitative analysis of the samples was carried out in the plasma flow of a DGP-50M two-jet plasmatron. Sampling was carried out on the basis of zoning of the urban area, taking into account emissions from thermal power plants, vehicles, and the residential area of the city. In samples taken at three sites in Bishkek in summer and winter, the content of 8 elements of the group of heavy metals was determined. The content of heavy metals in samples did not exceed the environmental standards established by the parameters of the maximum permissible concentration and the maximum permissible excess.

The algorithm for processing lidar sensing data at wavelengths of 299/341 nm for a vertical atmospheric sensing trace with spatial resolution of 1.5—150 m has been developed and implemented. The program includes the main functions: recording the data of lidar sensing of the atmosphere, converting the dat binary file format to the text txt format, retrieval of ozone concentration profiles. The software package developed on the basis of the created algorithm for processing lidar sensing data allows one to obtain ozone concentration profiles from 4 to 20 km. The data recording units for lidar sensing of the atmosphere and retrieval of ozone concentration profiles provide visual monitoring of recorded echo signals and retrieved ozone concentration profiles. An example of retrieving the ozone concentration profile from lidar data is given.

The destruction of 4-cyanophenol is considered using photolysis and activated oxidative processes in aqueous solutions. The effect of UV radiation of two KrCl and XeBr excilamps on its absorption spectra has been studied. It is shown that for obtaining an effective photodegradation, it is necessary to supplement the direct photolysis using KrCl excilamp with adding hydrogen peroxide to an aqueous solution of 4-cyanophenol in order to turn on the mechanism with the participation of hydroxyl radicals.

Caesium-lead-triiodide (CsPbI₃) – based inorganic perovskites are the most perspective material for production of perovskite solar cells (PSC) due to the optimal width of energy gap in them, about 1.72 eV and high light absorption coefficient. The latter is the characteristic of the cubic structure of CsPbI₃, called the black phase. To form such a structure at relatively low temperatures, it is required to add hydroiodic acid (HI) to the perovskite solution from which the structure is prepared. Structural, morphological, optical and photoelectrical parameters of CsPbI₃ solar cells at various concentrations (added quantity) of HI acid have been studied. The most important characteristics of CsPbI₃ – based PSC with maximum efficiency of 8.85% obtained at HI acid concentration of 66 µl/ml are described.

A monocrystal rutile (TiO₂) plate implanted with cobalt ions at a fluence of 1.25×10¹⁷ ion/cm² with an energy of 40 keV at a constant current density in the ion beam of 2 μA/cm² at a temperature of an irradiated substrate 620 °C was studied with the method of light reflection and transmission spectroscopy in the visible region of the spectrum. The spectral dependences of the optical parameters of the modified layer were obtained. The calculated optical Tauc gap of the layer was 0.2–0.3 eV.

The main focus of this study is the spectroscopic properties of highly charged hafnium ions. Highly charged ions of high-Z elements (Z ~ 70–83) are of great importance in atomic physics, astronomical physics and especially plasma diagnostics. Therefore, we perform level energies, transition probabilities, wavelengths, and line strengths for electric dipole, electric quadrupole, and magnetic dipole transitions in Hf LXII (Hf⁶¹⁺, Z = 72). All values are calculated using the AUTOSTRUCTURE atomic structure code whose relativistic corrections are introduced according to the Breit–Pauli distorted wave approach. Valence–valence, core–valence and core–core electron correlation effects are included. The results are compared with other studies from the National Institute of Standards and Technology database. The present results are in good agreement with other studies in the literature. We hope to fill a lack of atomic data for highly charged hafnium ions, which may be useful in plasma diagnostics.

Nowadays zinc nanoparticles (NPs) have attracted many applications in display technology. Due to the dispersion of nanoparticles in liquid crystals (LCs), the display properties are enhanced. The present work focuses on the significant changes in the properties of LC displays with the dispersion of ZnO NPs. Schiffbased LC compounds like p-n-decyloxybenzaldehyde and corresponding p-n-alkoxyanilines (10O.Om, with m = 3, 6) are prepared with the dispersion of ZnO NPs (1 wt%). The tools used to characterize the nanoparticles in LCs are X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and modified spectrometer. With XRD studies, the size of ZnO NPs is determined. By using SEM and EDS, the homogeneous dispersion and elemental analysis is estimated. With the data of POM, the textural analysis is examined. With DSC, the phase transition temperature of different phases is noted. With the modified spectrometer, the values of refractive indices and birefringence are determined. Furthermore, with these values, the molecular orientational order parameter S is measured by the Kuczynski and Haller Extrapolation methods. It is observed that the birefringence and order parameter values are decreased with the dispersion of 1 wt% ZnO NPs in Schiff based LC compounds.

ZnCdO is a perfect material for ZnO-based gadgets. ZnCdO nanocomposites are mainly used in most optoelectronic and display device applications. In the present investigation, a simple solution method was used to synthesize pure ZnCdO and Ti-doped ZnCdO nanocomposites with different wt% ratios (0.1, 0.3, and 0.5%). Characterization techniques such as the structural, morphological, and elemental composition of the prepared samples were undertaken by X-ray diffraction, scanning electron microscopy (SEM), energydispersive X-ray analysis, and photoluminescence (PL). The diffraction peaks of the prepared samples revealed the cubic phase structure. SEM showed the presence of spherical chunks with irregular grains due to agglomeration. For the prepared sample of pure ZnCdO, the particle size was found to be 62.08 nm, whereas Ti-doped ZnCdO nanocomposites (0.1, 0.3, and 0.5%) were at 55.08, 50.03, and 45.08 nm. The peak observed in PL spectra at 520 nm could be ascribed to the near-band-edge emission. The photo-generated electrons have been trapped in to Ti4+ levels in the forbidden gap, which enhanced the deep-level emission.

To solve the problem of multiple noise interference when tunable diode laser absorption spectroscopy (TDLAS) technology is used for gas concentration detection, the principles of Kalman, moving average, wavelet transform, and singular value decomposition four filtering algorithm principles and system noise sources are analyzed. MATLAB simulation software is used to simulate the relationship curve of thermal noise, shot noise, relative intensity noise of lasers, and the characteristic value of harmonic signals. Four filtering algorithms are used to process the noise, and the best filtering algorithm is selected. Moreover, a TDLAS experimental system with ethylene gas as the detection object is designed in this paper. The experimental results show that the singular value decomposition method among the four filtering algorithms has the best effect in removing thermal noise, shot noise and laser noise. After filtering is performed, the accuracy of the continuous detection of the system is improved, and the purpose of reducing or even eliminating system noise can be achieved. After processing occurs, the signal-to-noise ratio of the detected signal of the system is improved by 57 dB, and the noise removal rate of the system reaches 66.7%.

Idelalisib is a phosphatidylinositol 3-kinase delta inhibitor approved by the USFDA and EMA for the treatment of lympholytic lymphoma, B-cell non-Hodgkin lymphoma and lymphocytic lymphoma. The present report describes the validation of simple, rapid, sensitive, and cost-effective spectrofluorimetric methods based on the native fluorescence of the drug in an acidic medium. Fluorescence characteristics of the drug were found to significantly differ in absolute ethanol (λ_ex = 330 and λ_em = 595 nm) and HCl (λ_ex = 270 and λ_em = 350 nm) and both methods were validated as per ICH guidelines. The two methods were extremely sensitive, precise and accurate demonstrating excellent linearity in concentration ranges from 0.1–2.0 μg/mL (absolute ethanol) and 0.1–20 μg/mL (HCl). The LOD and LOQ values were found to be 0.015 and 0.045 µg/mL (ethanol) and 0.1615 and 0.4894 µg/mL (HCl). The proposed methods were used to quantify the drug in its marketed tablet formulation with good recoveries, suggesting their applicability to routine analysis of the drug in bulk as well as in formulation.

The antioxidant activities of flavonoid mixtures can be used to investigate the synergistic antioxidant mechanism of flavonoids. The antioxidant capacities of three flavonoids (quercetin, baicalein, and daidzein) and β -carotene in binary and ternary mixtures with kaempferol were analyzed using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition assay by means of absorption spectroscopy. The results showed that the number of hydroxyl groups and o-hydroxyl groups had a significant effect on the antioxidant activity of the flavonoids, and the mixture of kaempferol, quercetin, and baicalein showed optimal synergistic antioxidant activity. Compared with quercetin and baicalein, kaempferol had the fastest inhibition rate, and multiple prolonged kinetic processes associated with the scavenging of DPPH radicals occurred in mixtures of kaempferol with the other flavonoids and β -carotene. Kaempferol has a potential synergistic antioxidant effect when mixed with daidzein and β -carotene, and the results suggested that this may be due to the regeneration of kaempferol after antioxidation. By means of classic UV-Vis spectroscopy, reaction details of the synergistic antioxidant process of DPPH radical scavenging by flavonoids can be obtained.

Vildagliptin (VLG), a drug for the treatment of type 2 diabetes, is nonfluorescent in aqueous solution. This property makes it difficult to determine by direct fluorometric methods. We proposed a new competitive method for fluorometric detection of VLG using CB[7]–BER (cucurbit[7]uril = CB[7], BER = berberine) as a fluorescent probe. The method showed a good calibration curve within the concentration range 0.00213– 1.820 mg/mL with an excellent correlation coefficient (r² >0.999). The detection limit is 0.64 ng/mL for CB[7]–BER fluorescent probe. Moreover, the method was successfully applied for the determination of VLG in pharmaceutical tablets and artificial urine. To our knowledge, this is the first example of determining VLG using a fluorescent probe method.

Valbenazine tosylate, a benzoquinolizidine derivative, is a highly selective vesicular monoamine transporter 2 (VMAT2) inhibitor. It is the first and the only drug approved by the FDA for the treatment of tardive dyskinesia. Rapid, sensitive, and cost-effective first-order derivative UV spectrophotometric methods have been developed for the estimation of valbenazine in bulk and in its marketed formulation. Preliminary spectrophotometric determination of the drug was carried out in acetonitrile and in 0.1 N HCl with a total of 19 parametric variations for the two methods. The selected three-method variants employing peak–zero (P–0) and peak–peak (P–P) techniques were assessed for their stability, indicating potential in force degraded solutions of the drug. The developed methods were validated with respect to linearity, accuracy, precision, and robustness. Linearity was observed within the concentration range 5.0–70.0 μg/mL with an excellent correlation coefficient (r²) of 0.9998. The limits of assay detection values for the proposed method variants were found to range from 0.89 to 2.75 μg/mL, and quantitation limits ranged from 1.19 to 4.32 μg/mL. The proposed methods were applied for the determination of the drug in its marketed capsule formulation, and percentage recovery was found to range from 94 to 95%. 

Four simple, reproducible and rapid stability-indicating spectrophotometric methods were developed and efficiently applied for the estimation of zonisamide (anticonvulsant drug) in the presence of its oxidative degradation product. The degradation pathway was clearly illustrated and the structure of the degradation product was elucidated by infrared and mass spectroscopy. The proposed methods were the direct spectrophotometric method (D⁰), the first derivative method (D¹), the ratio difference method (RD) and, finally, the first derivative of the ratio spectra method ¹DD. Good sensitivity and high reproducibility were obtained via the developed methods. Linearity ranges were 5–40 µg/mL for the first method and 2–40 µg/mL for the other three methods. Mean recovery percentages of the methods were 100.12±0.590 for D⁰, 99.97±0.606 for D¹, 99.88±0.546 for RD, and 99.94±0.619 for ¹DD. The specificity of the methods was investigated by analyzing synthetic mixtures of different percentages of zonisamide and its oxidative degradation product. The proposed methods were validated in accordance with ICH guidelines. Statistical analysis showed no significant differences in comparison with the official method.

Seed variety purity is the main indicator of seed quality, which affects crop yield and product quality. In the present study, a new method for the identification of pine nut varieties based on hyperspectral imaging and convolutional neural networks LeNet-5 was established so as to avoid the hybridization of different varieties of pine nuts, improve the identification efficiency and reduce the cost of identification. Images of 128 wavelengths in the 370–1042 nm range were acquired by hyperspectral imaging. The spectrum and image of each seed were obtained by means of black-and-white correction and region segmentation of the original image. Twenty characteristic wavelengths were extracted from the first three principal components (PCs) of principal component analysis (PCA). A support vector machine (SVM) spectral recognition model based on full wavelengths and characteristic wavelengths was established. For different species of pine seeds, the classification accuracies of the prediction set in the aforementioned datasets were 97.7 and 93.1%, respectively. The seed images of 20 characteristic wavelengths were input into LeNet-5 to improve the network structure and the number of convolution channels. The improved LeNet-5 performed better with over 99% accuracy. Such results show that the convolutional neural network is of considerable significance for fast and nondestructive identification of pine seed varieties.

Oil content plays an important role in oilfield wastewater treatment. To investigate the forecast of oil content by UV spectrophotometry, samples of oilfield wastewater are collected, and their UV transmittance and turbidity are measured. Partial least squares (PLS) and convolutional neural networks (CNN) based on a dataset of UV transmittance spectra are used for quantitative analysis in this work. The correlation coefficient between the oil content and turbidity of oilfield wastewater is 0.924, which shows a high positive linear correlation between the oil content and turbidity. Turbidity is added to the dataset to investigate its influence on the accuracy of prediction. The results show that the accuracy of models built by transmittance and turbidity is higher than that of models built by transmittance only, which is confirmed for both PLS and CNN. With the same dataset composition, the PLS and CNN models are nearly accurate, but the CNN performs slightly better overall. This work laid the foundation for the prediction of oil content in oilfield wastewater based on UV spectrophotometry and the further implementation of online detection.

With methyl orange, Congo red, rhodamine B, methyl violet and methylene blue as the research objects, the accuracy of spectrophotometry in determining the dye concentration of two-component and threecomponent solutions with different ratios was evaluated. The experimental results showed that when the interference among dyes was small, the measurement errors of two-component and three-component solutions were less than 5 and 10%, respectively. Meanwhile, multicomponent spectrophotometry was applied to a degradation experiment of β-FeOOH to test its catalytic degradation performance in the mixed solution of methyl orange and Congo red. The results showed that in the case of single components, the degradation rate of methyl orange and Congo red with β-FeOOH was 44.64 and 71.95% (4 h), respectively, while in the mixed solution, it was 29.54 and 80.17% (4 h), respectively. The significance of this work is to evaluate the accuracy of multicomponent spectrophotometry and provide a low-cost as well as a rapid method for evaluating the multicomponent catalytic ability of photocatalysts.

Taking the fat content of six different brands of milk as the research object, hyperspectral reflectance data were obtained using hyperspectral imaging and image processing techniques. The raw data are preprocessed in seven different ways. Combine the three mature bionic algorithms – genetic algorithm (GA), ant colony optimization, and particle swarm optimization – with partial least squares (PLS) and support vector machine regression (SVR) models to filter characteristic bands, and to explore the linear and nonlinear relationship between milk spectral data and fat content. The correlation coefficient method, the uninformative elimination algorithm, the successive projection algorithm, the competitive adaptive reweighting sampling algorithm, four mature feature band selection methods, are compared with the bionic algorithm, and, according to the characteristics of each, are combined. The best combination of characteristic bands is selected to establish a regression model to detect milk fat content accurately. The band combination screened by GA and PLS achieved the best prediction results. A total of 72 bands were selected; the correlation coefficient of prediction was 0.9995, and the root mean square error of prediction was 0.0283. The experimental results show that higher accuracy can be obtained by establishing the PLS model using the characteristic bands screened by the linear relationship between spectral data and milk fat content. The SVR model was established based on the nonlinear relationship between spectral data and milk fat content. The accuracy of the SVR model was slightly lower than that of the PLS model. The selection of characteristic bands can improve the model’s prediction accuracy, and the use of hyperspectral technology can realize the accurate detection of milk fat content.

Photoionization of neutral potassium K I is investigated in the framework of the screening constant per unit nuclear charge (SCUNC) method. Transition energies and wavelengths belonging to 4p(²P_1/2)→nd ²D_3/2 and 4p(²P_3/2)→nd ²D_3/2,5/2 Rydberg transitions are reported. Accurate transition energies and wavelengths originating from 4p(²P_1/2,3/2) levels of K I are tabulated for 20 ≤ n ≤ 100. The SCUNC wavelengths are believed to be the first calculations that agree excellently with the existing experimental measurements up to n = 70 using linearly polarized laser light. The maximum shift in wavelengths relative to the experimental data is at 0.03 nm up to n = 70. New wavelengths are tabulated for n = 71–100 along with new transition energies for n = 20–100.