We studied the effect of the sequential formation of protonated and deprotonated forms of the 2,3,7,13,17,18-hexamethyl-8,12-di-n-butyl-corrole in solution on their photophysical characteristics and spectral-luminescent properties. It was found that in the ground electronic state the spectral characteristics of each of the two forms are the same when they directly formed from the free base and from the antipodal form, while the fluorescence spectra of each of two forms differ depending on their formation way. Based on the analysis of spectral shifts of fluorescence spectra and fluorescence quantum yields, it is concluded that the protonated and deprotonated forms of corroles undergo the specific interactions in the lowest excited singlet S₁ state, due to the formation of a complex solvation shell. It was shown that these specific interactions lead to hysteresis of the fluorescent characteristics of the protonated and deprotonated forms of corrole under their mutual transitions caused by (cyclic) changes in acid-base equilibrium. 

A fast and simple method for the synthesis of solid solutions based on erbium-doped yttrium oxide  (Y_1–xEr_x)₂O₃ has been proposed. The crystal structure of samples was determined by X-ray diffraction method. Compounds exhibit greenish-yellow upconversion emission upon IR laser excitation (980 nm). An increase in the erbium concentration in (Y_1–xEr_x)₂O₃ causes a change in the color of the upconversion luminescence and a growth of its intensity. The maximum intensity of the upconversion luminescence is observed for oxide with x = 0.05. Based on the pumping power dependence of intensity of emission lines associated with ²H_11/2/⁴S_3/2→⁴I_15/2 и ⁴F_9/2→⁴I_15/2 transitions, the two-photon excitation mechanism was determined. The absolute and relative sensitivities were calculated from the temperature dependences of the ratio of emission lines corresponding to transitions from thermally coupled excited ²H_11/2 and ⁴S_3/2 levels, these values showed the promise for use of oxides as materials for non-contact temperature sensing.

A comparative study of the luminescent properties of erbium(III)-doped fluorozirconate glass and fluorozirconate phosphate glass and glass ceramics containing NaPO₃ was carried out. The glasses were obtained by melt-quenching technique and characterized by methods of luminescent spectroscopy, differential thermal analysis, X-ray diffraction and transmission electron microscopy. When NaPO₃ is added, the relative luminescence intensity of Er(III) in the near infrared (IR) region doubles at 1530 nm (transition ⁴I_13/2→⁴I_15/2), the luminescence intensity of other bands in the visible and near IR regions decreases. The quantum yields and luminescence lifetimes of the studied samples were measured. The reasons for the change in luminescence intensity during the addition of NaPO₃ and after heat treatment of samples are discussed.

At room temperature, the pulsed cathodoluminescence spectra of zinc selenide were recorded, namely initial material and materials of its processing required for the synthesis of optical ceramics. Study objects were ZnSe samples of cubic phase and stoichiometric composition, as well as with the presence of additional phases – hexagonal ZnSe and ZnO. Three characteristic luminescence bands were detected in single-phase cubic zinc selenide. In cubic ZnSe of stoichiometric composition, one strong interband luminescence line with a width of 12–14 nm is observed in the region of 470 nm. An additional wide band at 647 nm appears with an excess of selenium. With an increased content of impurities and a small excess of zinc, a single band at 588 nm is observed. In two-phase materials containing cubic and hexagonal ZnSe as the main or additional phase, luminescence is not observed at room temperature. In cubic ZnSe with an additional hexagonal ZnO phase, except the interband luminescence line with a wavelength decreasing from 470 to 466 nm with increasing ZnO content, a strong broad doublet band of hexagonal ZnO appears at 525–900 nm. Based on the presence or absence of these pulsed cathodoluminescence bands, it is possible to carry out a rapid analysis of the quality of the ZnSe material.

This work examines the energy and spectral characteristics of the most powerful modern AlInGaN LEDs with peak emission wavelengths of 440, 470, and 510 nm in relation to pumping two laser media: Ti:Sapphire (Ti:Al₂O₃) and alexandrite (Cr:Al₂BeO₄). The absorption coefficients of LED radiation in laser media have been experimentally studied depending on the peak wavelength, operating mode, and excitation level. The corresponding values of spectral matching (efficiency of absorption of pump radiation) are calculated for various combinations of LEDs and active laser media. The energy characteristics (radiation power, energy per pulse) of LED emitters in a wide range of excitation levels have been studied. The maximum energy capabilities have been assessed, both in terms of output optical power and efficiency. The optimal combinations of LED and active laser medium to achieve lasing have been determined.

In the current work we employed dynamic light scattering as a method for analysis of hydrolyzed collagen (HC) quality and demonstrated that it could be effectively used as a fast and reliable approach in production and quality control. Also, we used ultrafiltration coupled with spectrophotometry for semiquantitative analysis of less than 10 kDa peptide fraction which determines the most demanded properties of HC.

The spectra of attenuated total reflection of polyimide PI-2610 films deposited on single-crystal silicon wafers by centrifugation are studied. The films were irradiated by electrons with energy of 5 MeV on a linear electron accelerator at doses of 1 · 10¹⁴–2 · 10¹⁵ cm^–2. The most intense in the spectrum of PI-2610 polyimide films are the C-N-C_st vibration bands of the imide ring (1349 cm^–1), aromatic ring vibrations (1517 cm^–1), C=O_str stretching vibrations of the imide ring group (1700 cm^–1), and stretching vibrations of C-C bonds in the CO-C_st group (1074 cm^–1), as well as bands of bending vibrations of C-H bonds with maxima at 734 and 828 cm^–1. At an initial dose of 1 · 10¹⁴ cm^–2, a change in the spectral shape and intensity of the bands with maxima at 1700 and 1349 cm^–1, caused by vibrations of the C=0 and C=N-C_str groups, was observed. It is assumed that this is due to the relaxation of the metastable states of these groups. At a dose of 2 · 10¹⁵ cm^–2,  a decrease in the intensity of bands caused by asymmetric and symmetric stretching vibrations of C-H₂ bonds was detected. The intensity of the ATR bands caused by vibrations of C=O and C-N bonds, aromatic and imide rings remained practically unchanged. 

Absorption spectra of Ti/SiO₂/Si₃N₄/n⁺-Si structures with an island surface layer were calculated. It is shown that with increasing islands size, the absorption peak with maximum intensity shifts to a longer wavelength region and its width increases. This peak is probably associated with the excitation of plasmon oscillations in the surface island layer. It is shown that a structure with an island size of 3 μm and period of 6 μm absorbs 99% of the incident radiation at a wavelength of 6.2 μm. It is found that other absorption bands at 4 μm and 9.0–9.5 μm do not depend on islands sizes and are associated with vibrations of bonds  in the dielectric layer. An additional layer of undoped silicon with thickness up to 200 nm located between the Ti substrate and the SiO₂ layer slightly reduces the intensity and semi-width of the plasmonic absorption peak.

The change of spectral-luminescent properties of fluorescein after its interaction with various reactive oxygen and halogen species (О₂^•–, H₂O₂, HOCl, HOBr, HOSCN, taurine N-chloramine and taurine  N-bromamine), as well as in the myeloperoxidase (MPO)-H₂O₂-Cl^–/Br^–/SCN^– system has been studied. It has been found that after interaction only with HOBr as well as in the MPO-H₂O₂-Br^– system fluorescein turns into a compound having an absorption maximum at 518 nm. The fluorescence maximum of this compound is recorded at wavelength of 540 nm when excited at wavelength of 520 nm, that corresponds to the characteristics of brominated fluorescein — eosin Y. Optimal conditions (phosphate-buffered saline (pH 7.4) containing 137 mM NaCl, 5 μM fluorescein, 15—30 mM NaBr, and 25—50 μM H₂O₂) for registration HOBr in solution have been selected; a qualitative method for determining MPO brominative activity in vitro has been proposed. Using the developed method, the effect of physiological and synthetic inhibitors, as well as reactive oxygen and halogen species scavengers, on the MPO brominating activity has been studied. Based on the data obtained, it can be concluded that, fluorescein is a promising compound for the development on its basis of a fluorescent method for detecting mammalian heme-containing peroxidases brominating activity.

We conducted a spectral analysis of enamel, enamel-dentin junction, and dentin of teeth in women with and without connective tissue dysplasia (CTD) in five age groups: 14–17, 18–21, 22–26, 27–31, and 32–36 years. Using the principal component method, 19 absorption bands in the IR spectra of hard dental tissues were analyzed and the possibility of grouping the samples by age and the presence/absence of CTD was assessed. It was shown that the maximum changes in the functional group composition of dental hard tissues in case of connective tissue dysplasia were observed in the enamel-dentin junction and are mostly pronounced in the younger age group (14–17 years). In this age group, the intensity of collagen absorption bands in dentin was reduced by 30–50% (1202, 1249, and 1342 cm^–1), while the intensity of phosphate absorption bands was reduced by 50–70% in the enamel (1037 and 1050 cm^-1). In this very group the lower third molars erupt with an insufficient level of maturity, in a hypomineralized state, which may be associated with a decrease  in the content of collagen and a change in its structure due to the presence of connective tissue dysplasia. The data obtained make it possible to review preventive measures and prenosological diagnostics of diseases of teeth and maxilla, based on the connective tissue theory of eruption.

High-performance liquid chromatography (HPLC) and Raman spectroscopy have been used to study the process of thermal degradation of amoxicillin trihydrate at temperature of 60 ºС. It has been established that when the substance is heated for 6 hours, the content of some impurities increases, the amount of which does not exceed 1%. It is shown that both the HPLC method and the Raman spectroscopy method can be used to evaluate the quality of the amoxicillin substance obtained by thermal degradation at 80 ºС.

Using the method of differential absorption photometry, the kinetics of oxidation/reduction of P700, plastocyanin (PC) and ferredoxin (Fd) in the first leaves of barley seedlings under exposure to high-intensity light (2.000 μmol quanta  m^–2  s^–1, 30 min) and elevated temperature (40 °C, 3 h) were studied. Exposure to high-intensity light increased the accumulation of the primary oxidizer P700⁺, oxidized PC and reduced Fd. Under the same conditions, the absence of reoxidation of reduced Fd under red and far-red light was noted. In barley seedlings exposed to elevated temperatures, there was an increased accumulation of P700⁺, oxidized PC and reduced Fd, as well as accelerated reoxidation of leaf Fd under red light and no accumulation of oxidized Fd under far-red light. It was concluded that the photoindependent electron flow through Fd under light stress and alternative electron flows with the participation of the plastoquinone pool under heat stress were activated.

The paper presents the results of studies of the interaction of indotricarbocyanine dyes with the lipid transfer protein Ns-LTP1 in Dulbecco’s phosphate-buffered saline (PBS). It has been shown that the orthophenylene bridge with chlorine in the meso position of the dye is not effective as a linker for protein macromolecules that do not have a free cysteine residue. To obtain a complex of indotricarbocyanine dye with the Ns-LTP1 protein, the indotricarbocyanine dye has been modified into N-hydroxysuccinimide ester. As a result of mixing in a two-phase system – the protein in PBS and the activated dye ester in 1,2-dichloroethane – a complex of dye molecules with the Ns-LTP1 protein has been obtained. Upon formation of the complex, an increase in the half-width of the absorption spectrum from 56 to 61 nm, an increase in fluorescence decay time from 0.3 to 0.5 ns, and an increase in its degree of polarization from 27 to 31% are observed. It has been established that hydrochloric acid at concentrations being equivalent to its content in gastric juice (0.1–0.5%) leads to irreversible destruction of the dye. When treating erosive and ulcerative lesions with oral administration of the complex, capsules that can withstand stomach acid and dissolve in the intestines can be used.

On the basis of complex studies using modern spectroscopic methods (UV-spectroscopy, IR-spectroscopy, NMR-spectroscopy, and luminescence), the process of photooxidation of aromatic hydrocarbons isolated from crude petroleum from the Zagly field using liquid adsorption chromatography, as well as changes in the chemical composition, spectral parameters and spectral luminescent properties.

Statistical characteristics of data from coordinated lidar and radiometric sounding of the atmosphere carried out by ground-based solar radiometers and satellite lidar CALIOP are used as input data set for retrieving the altitude profiles of aerosol parameters. The signal-to-noise ratio of input satellite lidar signals increases when averaged over a general ensemble of experimental data. An algorithm and software package have been developed for collecting and statistical processing of combined lidar and radiometric sounding data sets and calculating average aerosol optical parameters. Based on the results of radiometric measurements at the Minsk site of the AERONET/PHOTONS network and lidar sounding data from CALIOP collected during the observation period from 2015 to 2019, altitude profiles of average concentrations of aerosol fractions in the region of Belarus have been calculated. A statistical approach to the synergy of satellite lidar and ground-based radiometric sensing data is effective for studying the long-term and large-scale aerosol changes in regions with the low and medium content of aerosol matter in the atmosphere.

The current-voltage and capacitance-voltage characteristics of InGaAs/InP heterostructure p-i-n photodiodes fabricated by mesa technology have been studied. Photodiodes of circular configuration differ in active region diameter from 0.05 to 2.5 mm. All measurements are performed in the dark at room temperature using the probe method on a wafer with ready-made devices. Data are obtained on dark currents (leakage currents), I_dark, which are interpreted in terms of the surface and bulk currents in p-i-n photodiodes of various sizes. In the absorbing layer of the InGaAs/InP photodiode heterostructures, the concentration profiles N_D(x) are assessed for the first time by the non-destructive CV method and are compared with the electrochemical profiling data. It is shown that for the most part of the heterostructure i-layer both methods are complementary. 

Different concentrations of B₂O₃ in zinc-aluminum-sodium-phosphate (ZANP) glasses were synthesized by the conventional melt-quenching method and analyzed using X-ray diffraction (XRD), optical absorption, excitation, visible luminescence, decay lifetime, and chromaticity. The amorphous nature of the glasses was confirmed by the absence of sharp diffraction peaks in the XRD profile. In the visible emission spectra blue, yellow, and red bands were observed and the intensity of the yellow band was superior. Furthermore, the samples show a luminescence quenching beyond 20 mol.% of B₂O₃ concentration. The decay lifetime of ⁴F_9/2 of Dy³⁺ ions was found to be maximal in ZANPDy0.5:20B₂O₃ glass. 

A new phosphor Sr₅(BO₃)₃Cl:Ce³⁺,Yb³⁺, which enables near-infrared (NIR) quantum cutting, was prepared using traditional solid-state reaction methods. Its properties were examined using X-ray diffraction, photoluminescence emission, excitation spectra, and measurements of fluorescence decay. Upon excitation of Ce³⁺ with an ultraviolent (UV) photon at 350 nm, broadband emission at 415 nm and an intense NIR emission at 982 nm were observed. Emission at 415 nm corresponds to 5d→4f transition of Ce³⁺ ions, whereas the NIR emission at 982 nm is ascribed to the characteristic ²F_5/2→²F_7/2 transition of Yb³⁺ ions. Thorough investigation delved into how the concentration of Ce³⁺ affects visible and NIR emissions, decay lifetime, and energy transfer efficiency (η_ETE). Detailed analysis of photoluminescence excitation, emission spectra, and fluorescence decay measurements revealed a proficient energy transfer from Ce³⁺ to Yb³⁺ ions. This transfer was demonstrated as a cooperative energy transfer (CET) process, showcasing a CET efficiency of 71.2% and a total theoretical quantum efficiency of 171.2%.

The rapid identification and classification of metal garbage has been experimentally investigated. By combining laser-induced breakdown spectroscopy (LIBS) and machine learning, metal garbage can be effectively identified through spectral analysis. In this work, a novel method for metal garbage classification was developed, and a LIBS system was self-developed. As an example of metal recycling, five types of metal were adopted. Several characteristic lines of Al, W, Fe, Cu, Sn, Pb, and C were identified. For a more effective classification, principal component analysis was conducted to reduce the dimension of the spectra. Samples after the dimension reduction were classified by using K-nearest neighbors, and five types were obtained, exhibiting a final classification accuracy of 97.18%. Moreover, a mathematical model of the linear formulas between spectrum and concentration was established to achieve quantitative analysis with Fe taken as an example, laying the foundation for more refined classification.

Empagliflozin, an inhibitor of SGLT-2, a sodium glucose co-transporter is found mainly in the proximal tubules of the nephronic components of the kidney. The assay of empagliflozin in its tablet form has been created using a unique, secure, and sensitive UV-spectrophotometric approach. During the development and validation of the method for the assay of empagliflozin, methanol was employed as the solvent. The maximum absorbance wavelength of the solution was determined by scanning in a UV spectrophotometer. At the specified wavelength; absorbance was measured using a variety of calibration standards. The linearity and range of the calibration curve of concentration vs. absorbance were computed. The accuracy, precision, limit of detection, limit of quantitation, and ruggedness of the analytical approach were among the metrics that were determined. A correlation coefficient of 0.999 indicated linearity within the concentration range  2–10 µg/mL. The maximum absorbance of empagliflozin in methanol was determined to be 238.5 nm. Recovery was estimated as per International Conference on Harmonization guidelines and was found to be as per the acceptance limits: 93.25%. The developed UV method was found to be precise with relative standard deviation less than 2%. The assessment of empagliflozin in its tablet formulation using a UVspectrophotometric technique was determined to be both safe and helpful. The uniqueness of this research is based on a costefficient, time-saving, safe, easy, and successful approach for validating empagliflozin.

Lead in any food is harmful even at low concentrations. In this study, a direct and highly sensitive lead analysis technique was developed for wheat flour using laser-induced fluorescence combined with laserinduced breakdown spectroscopy. Wheat flour was pressed into small pellets and ablated by a low-energy ultraviolet 266-nm laser. A tunable dye laser constructed in our laboratory was used to resonantly excite the lead. The optimized interpulse time delay was 400 ns. A calibration curve was constructed and the detection limit for lead was 73.8 ppb. This method could be used to directly and sensitively analyze wheat flour for trace concentrations of lead. 

The removal of Cd(II) ions was investigated from various samples of water employing magnetic acrylamide nanocomposite. The effects of magnetic acrylamide nanocomposite dosage, pH extraction, and contact time on Cd(II) removal from sample water were monitored using spectrometry. In addition, adsorption isotherm models for the sorption of Cd(II) were studied in this research. The adsorption capacity of magnetic acrylamide nanocomposite for Cd(II) was achieved at 18.64 mg/g. The removal of Cd(II) using magnetic acrylamide nanocomposite was fitted with the model of the Freundlich isotherm. This removal process provides a value coefficient (R² = 0.98) for Cd²⁺ ions and a very excellent linear range of  0.4–22 mg/L. By using a signal-to-noise ratio of 3 (limit of detection, LOD = 2.04 µg/L), the LODs for Cd²⁺ ions adsorption by magnetic acrylamide nanocomposite were attained. According to these results, magnetic acrylamide nanocomposite is a suitable adsorbent for removing Cd(II) from various water samples.

Rapid detection of trace heavy metal ions in water is of great relevance to the environment and human health in the future. With pyrimidine as the parent structure, the water-soluble thiourea group is skillfully introduced to form a symmetric framework, thus firmly capturing the heavy metal ions in the water. The responsiveness of heavy metal ions in water was observed by UV-fluorescence spectroscopy. Especially with Co(NO₃)₂, Cu(NO₃)₂, Ni(NO₃)₂, and Zn(NO₃)₂, the response changes are most significant. The rapid response changes between them and trace heavy metal ions in water were intuitively observed under sunlight and fluorescence irradiation environment.

Iron, as the most prevalent critical trace element in the human body, is crucial for many basic physiological functions and has many environmental applications. Therefore, excellent chemosensors with high sensitivity and good selectivity toward iron are highly desired. Three new fluorescent colorimetric chemosensors (CS1, CS2, and CS3) were synthesized and prepared through a one-step reaction to selectively detect Fe³⁺ in aqueous media. To effectively coordinate metal ions, the sensors contain rhodamine derivatives with different “N, O” donor atoms. Of these sensors, CS2 and CS3 demonstrated sensing behavior and colorimetric “off-on” sensing for Fe³⁺ over various biologically important metal ions, rendering good selectivity. Fluorescent imaging was performed to confirm the possibility of applying the sensors in living cells.

The main theme of the paper was focussed on  the preparation, structural, optical and photoluminescence studuies of p(-n-decyloxy) benzoic acid (10OBA) liquid crystalline (LC) compounds with 1 wt% dispersed ZnO nanoparticles (NPs). The prepared samples were subsequently characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical polarizing microscopy (POM), differential scanning calorimetry (DSC), UV-Visible spectroscopy, and photoluminescence (PL) studies. From the XRD, the diffraction peaks observed at 36.2, 42.5, 61.3, and 73.2^o were well resolved, indicating the presence ZnO NPs and the particle size was found to be 65 nm. SEM studies revealed the uniform dispersion and the presence of ZnO NPs in the samples. The textural images of different phases (nematic, smectic) of liquid crystalline compounds of 10OBA pure and 10OBA with 1 wt% dispersed ZnO NPs were observed through the POM with reduced temperature. From the DSC thermograms, the phase transition temperatures and the correponding enthalpy values were estimated. The bandgap reduces for 10OBA LC compound with the dispersion of 1 wt% ZnO NPS and it is estimated as 3.25 eV compared with 4.25 eV for the undoped 10OBA LC compound. PL studies showed the presence of the peak at 616 nm owing to the presence of point defects within the bandgap-like vacancies and interstitials known as deep-level emission.

Herein, an accurate and simple spectrophotometric method for investigating cefixime in different formulations is reported. The proposed method elaborates on the complexation of cefixime with vanadyl sulfate in acidic media. The yellow color complexation product manifested its maximum absorbance peak at around 321 nm, and obeyed Beer’s law in 210⁻⁶–110⁻⁴ M cefixime concentration. Obtained spectroscopic data were used to calculate standard deviation (S), limit of detection (LOD), limit of quantification (LOQ), and relative standard deviation (RSD) as 6.5×10⁻⁵, 1.96×10⁻⁴, 6.5×10⁻⁴ M, and 0.057%, respectively. In addition, the formation constant associated with the complex obtained, calculated as 5.7×10¹⁶, indicates that the final complex was remarkably stable.

Y₂Sr₃B₄O₁₂ phosphors doped with europium ions were synthesized by a modified conventional solidstate reaction method. Characterizations of the prepared samples viz. X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and Commission Internationale de I'Eclairage were studied. The XRD analysis confirmed the formation of mixed phase due to polyborate and has a hexagonal crystalline yttrium orthoborate phosphor. SEM images showed the irregular morphology of the sample. The grain size distribution was broad and the average size was found to range from 2 μm to 100 nm. PL measurements showed excitation and emission characteristics of the prepared phosphor with different concentrations of the doping ion. From the emission spectra, it was clearly observed that the emission intensity of the magnetic dipole was higher than that of electric dipole transition owing to the Eu³⁺ ions occupying a higher symmetry site in the Y₂Sr₃B₄O₁₂ host. The intensity of PL increased with increasing concentration of the dop ing ion up to 2.0 mol.%; after that, the PL intensity decreased owing to the concentration-quenching phenomenon. The results indicated that Y₂Sr₃B₄O₁₂:Eu³⁺ phosphors can be selected as a potential candidate for solar cell/photovoltaic application.  

This paper is aimed at investigating the structure and luminescence properties of Sr₃Y₂Ge₃O₁₂ activated by Eu³⁺ (SYGO:Eu³⁺), which were synthesized by using the sol-gel method. The synthesis was conducted at 1200°C for 8 h, with an optimal doping concentration of 5 mol% Eu³⁺. Under near-ultraviolet excitations at 395 nm, SYGO:x mol.% Eu³⁺ phosphors showed the red emission of Eu³⁺ (⁵D₀–⁷F₁) at 612 nm, and the photoluminescence intensity was highest at 5 mol.% Eu³⁺ doping. X-ray diffraction analysis of SYGO materials displays a single-phase structure that belongs to the Ia3d (230) space group. The result showed that the Eu³⁺ ion substitutes the asymmetrical location in the SYGO host, particularly the Sr²⁺ position, by calculating the ionic radius. In addition, the investigated red phosphors show high luminescence intensity and deep red emission. Thus, they show application potential as red-emitting phosphor materials in white LEDs under near-ultraviolet excitations.

Owing to variation of moisture content, the larch wood basic density near-infrared (NIR) prediction model shows reduced accuracy and robustness, or even model failure. To solve this technical problem, a multi-verse-algorithm-optimized BP neural network (MVO-BPNN) prediction model is proposed to improve the accuracy of the model. The preprocessing effects of the Savitzky–Golay smoothing, detrending, and 15point moving average smoothing method were compared. The synergy interval partial least squares was used to extract the feature bands of the NIR spectra. Results showed that the prediction model based on MVO-BPNN was better than those based on BPNN and the genetic algorithm-optimized BPNN. It indicated that the NIR model based on the MVO-BPNN could effectively predict the basic density of wood with different moisture contents.

Detection of nonstructural protein 1 (NS1) in saliva is a potential solution to non-invasive, early dengue detection. However, NS1 in saliva detected using enzyme-linked immunosorbent assay reports only 64.7% sensitivity and is undetectable using rapid test kits even in acute cases. Exploiting surface-enhanced Raman spectroscopy (SERS) and silicon (Si) as a low-cost, abundant material, a nano silver-coated porous silicon SERS substrate was developed for the novel detection of low-concentration NS1. The conventional wet lab electrochemical method was used to fabricate the PSi template, whereas the drop deposition method was used to deposit the AgNP on the PSi. Using rhodamine as the Raman marker, an enhancement factor of 53 was obtained, with a 0.01-mg/mL limit of detection (LOD), which is not spectacularly impressive. However, surprisingly, the SERS substrate surface functionalized with the dengue antibody resulted in the visibility of several peaks related to NS1 up to 0.001 mg/mL. Advanced lithography methods can further lower the LOD and enhance the performance of the PSi-based SERS substrate. Moreover, PSi-based SERS substrate fabrication allows for mass production and low costs. The study successfully developed the SERS substrate for its intended novel application: to detect low-concentration NS1.