Maximum Absorption Research Articles

Chitosan-TPP encapsulated quercetin nanoparticles: amplified protection mechanisms unveiled against Ethion-induced developmental toxicity through comprehensive in-vivo and in-silico elucidation.

The study investigated Ethion-induced developmental toxicity in Wistar albino rats and the potential ameliorative effects of quercetin and nano-quercetin co-administration. Further, In-silico docking of Ethion and quercetin with MCL-1 was conducted. Quercetin nanoparticles were synthesized by ionic-gelation method. The encapsulated quercetin nanoparticles were characterized for Zeta size, UV-Vis spectroscopy, encapsulation efficiency, and TEM studies. Male rats were administered Ethion (high/low dose), quercetin, and nano-quercetin alone or in combination for 60 days. Female rats were introduced for mating on the 61st day, and pregnant females were observed for 20 gestational days. On GD 20, rats were sacrificed and evaluated for body/organ weight, reproductive indices, fetal morphology, skeletal, and visceral deformities.In silico binding energies of ethion and quercetin with MCL-1 were determined. Nanoparticle size was 363.2 ± 1.23 nm on day 0 and 385.63 ± 1.53 nm on day 60, with PDI of 0.247 and charge of 22.9 mV. Absorbance maxima were at 374 nm, with encapsulation efficacy of 85.16 ± 0.33%. EHD male crossed females showed decreased body/organ weights, reduced fertility, hematoma, cleft palate, tail curling, and absence of extremity. Nano-quercetin co-administration normalized parameters comparable to controls. Both Ethion and quercetin interacted with MCL-1, with quercetin exhibiting stronger binding energy. Nano-quercetin demonstrated stronger antioxidant properties than quercetin, counteracting ethion-induced maternal/fetal abnormalities.

Design and optimization of a corrugated tubular shell structure based on triply periodic minimal surface

A novel corrugated tubular shell structure based on triply periodic minimal surface (TPMS) was proposed in this study. The initial diamond tubular thin-walled structure (D-TTS) and corrugated tubular thin-walled structures (C-TTS) model were designed and then fabricated using selective laser melting (SLM). The 3D-printed model deviation distribution was obtained by using computed tomography (CT) scanning. Compressive behaviors and energy absorption capacity of the tubular thin-walled structures were investigated using experimental and numerical methods. To obtain optimal designs of C-TTS, a surrogate model was established and multi-objective optimization was carried out. The maximal specific energy absorption (SEA) and the minimal peak crushing force (PCF) were obtained by non-dominated sorting genetic algorithm II (NSGA-II). Compared with the initial D-TTS, maximal SEA is increased by 9.34%, and the minimal PCF is reduced by 58.96%. This structure enhances the diversity of tubular structure designs while also inspiring innovative approaches for developing energy absorption devices and structures utilizing TPMS.

Xác định acetamiprid bằng phương pháp quang học sử dụng dung dịch nano vàng được ổn định bằng Polydiallyldimethylammoni clorua

On this research, the development of a simple, cost-efective and highly sensitive spectrophotometric method for acetamiprid detection based on the localized surface plasmon resonance of polydiallyldimethylammonium chloridestabilized gold nanoparticles. By naked eyes, one can detect acetamiprid by the visual change of gold solution color from red to purple, corresponding to the shift of maximum absorbance wavelength in the UV-Vis spectrum. Quantification of acetamiprid is possible through a linear relationship between the maximum absorbance wavelength and the acetamiprid concentrations in the range of 8×10-8 -2×10-6 M. Under the optimum conditions including pH 5, NaCl concentration of 0.02 M and incubation time 20 min, the present method has high precision (RSD < 5%), very low limit of detection (LOD) of 2.7×10-8 M, limit of quantification (LOQ) of 8.2×10-8 M. This method has been successfully applied to determine acetamiprid in several pesticide samples and vegetable samples. The measurement results of acetamiprid in the pesticide samples of the research method with the HPLC-UV method showed a difference of < 2%, while for the vegetable sample, the difference between the research method and the LC-MS/method method/ MS < 5% shows that the method has high accuracy and reliability.

Designing efficient materials for high-performance of non-fullerene organic solar cells through side-chain engineering on DBT-4F derivatives by non-fused-ring electron acceptors.

For the advancement in fields of organic and perovskite solar cells, various techniques of structural alterations are being employed on previously reported chromophores. In this study, the end-capped engineering is carried out on DBT-4F (R) by modifying terminal acceptors to improve optoelectronic and photovoltaic attributes. Seven molecules (AD1-AD7) are modeled using different push-pull acceptors. DFT/B3LYP/6-31G along with its time-dependent approach (TD-DFT) are on a payroll to investigate ground state geometries, absorption maxima (λmax), energy gap (Eg), excitation energy (Ex), internal reorganization energy, light harvesting efficiency (LHE), dielectric constant, open circuit voltage (VOC), fill factor (FF), etc. of OSCs. AD1 displayed the lowest band gap (1.76eV), highest λmax (876nm), lowest Ex (1.41eV), and lowest binding energy (0.21eV). Among various calculated parameters, all of the sketched molecules demonstrated greater dielectric constant when compared to R. The highest dielectric constant was exhibited by AD3 (56.26). AD5 exhibited maximum LHE (0.9980). Lower reorganization energies demonstrated improved charge mobility. AD5 and AD7 (1.63 and 1.68eV) have higher values of VOC than R (1.51eV). All novel molecules having outperforming attributes will be better candidates to enhance the efficacy of OSCs for future use. Precisely, a DFT and TD-DFT analysis on all of the proposed organic molecules were conducted, using the functional MPW1PW91 at 6-31G (d,p) basis set to examine their optoelectronic aspects, additionally the solvent-state computations were studied with a TD-SCF simulation. For all these simulations, Guassian 09 and GuassView 5.0 were employed. Moreover, the Origin 6.0, Multiwfn 3.8, and PyMOlyze 1.1 software were utilized for the visual depiction of the graphs of absorption, TDM, and DOS, respectively of the studied molecules. A number of crucial aspects such as FMOs, bandgaps, light-harvesting efficiency, electrostatic potential, dipole moment, ionization potential, open-circuit voltage, fill factor, binding energy, interaction coefficient, chemical hardness-softness, and electrophilicity index were also investigated for the studied molecules.

Development of absorption spectrophotometry of iron(III) in environmental water and sediments using NEDA and its application to the field.

In this study, we developed a simple method that enables iron(III) in environmental water to be directly determined via spectrophotometry. In water samples, iron(III) formed a yellowish complex with N-1-Naphthylethylenediamine dihydrochloride (NEDA) at pH 2.0-2.8, the maximum absorption wavelength of which was 462nm. Detection sensitivity increased in the presence of chloride ions and remained constant for 2-24h with 0.05-0.57molL-1 chloride. Therefore, NEDA solution containing chloride ions was used as a chromogenic reagent for the determination of iron(III). The determination range for this method was 0.1-20mgFe(III)L-1 in a 5cm glass cell. The developed method is highly selective for iron(III) and has been successfully applied to freshwater, brackish water, seawater, turbid water in rivers, as well as to riverbed and freshwater lake sediments. In addition, a combination of the proposed NEDA method and the 1,10-phenanthroline method enabled simultaneous determination of iron(III) and iron(II).

Green synthesis of silver nanoparticles using Hebeloma excedens mushroom extract as a new source: Anti-lipid peroxidation, bioaccessibility and antidiabetic properties

AbstractA traditional source of natural bioactive compounds, mushrooms are used to synthesize biomaterials, thanks to their potential applications in the medicine, pharmacology and cosmetics industries. In this study, the vitamin C and E contents of the Hebeloma excedens mushroom species were determined as 64.2 mg/g and 38.6 mg/g, respectively. In the mineral substance analysis, the highest amount of magnesium (32.16 mg/g) and trace amounts of iron (0.22 mg/g) were detected. In the nanoparticles (AgNPs/He) synthesized using this mushroom species, the colour of the mixture first changed to dark brown and exhibited maximum absorption at 428 nm, corresponding to the surface plasmon resonance. Fourier transform infrared spectroscopy (FTIR) results revealed the binding properties of the biocomponents responsible for coating and stabilizing the nanoparticles. The resulting nanostructures were much more stable than the mushroom extract and showed strong antioxidant activity (22.93 mg/ml). A significant decrease in phenolic compounds was observed after the gastrointestinal digestion process applied to the mushroom extract and AgNPs/He samples (p < 0.05). However, a significant increase in the bioaccessibility of phenolic compounds was detected in AgNPs/He particles (p < 0.05). It was determined that there was a significant increase in the thermal stability, inhibition against lipid peroxidation (6.64 mg/ml) and antidiabetic activities (29.20 mg/ml) of silver structures synthesized using the green synthesis method. As a result, the existence and current potential of a new biomaterial suitable for cost-effective and large-scale production in the synthesis of AgNPs/He has been demonstrated for the first time.

A comparative study of the biosynthesis of CuNPs by Niallia circulans G9 and Paenibacillus sp. S4c strains: characterization and application as antimicrobial agents

BackgroundBiosynthesis of metallic nanoparticles using microorganisms are a fabulous and emerging eco-friendly science with well-defined sizes, shapes and controlled monodispersity. Copper nanoparticles, among other metal particles, have sparked increased attention due to their applications in electronics, optics, catalysis, and antimicrobial agents.ResultsThis investigation explains the biosynthesis and characterization of copper nanoparticles from soil strains, Niallia circulans G9 and Paenibacillus sp. S4c by an eco-friendly method. The maximum reduction of copper ions and maximum synthesis CuNPs was provided by these strains. Biogenic formation of CuNPs have been characterized by UV–visible absorption spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray analysis and transmission electron microscopy analysis. Using UV-visible spectrum scanning, the synthesised CuNPs’ SPR spectra showed maximum absorption peaks at λ304&308 nm. TEM investigation of the produced CuNPs revealed the development of spherical/hexagonal nanoparticles with a size range of 13–100 nm by the G9 strain and spherical nanoparticles with a size range of 5–40 nm by the S4c strain. Functional groups and chemical composition of CuONPs were also confirmed. The antimicrobial activity of the biosynthesized CuNPs were investigated against some human pathogens. CuNPs produced from the G9 strain had the highest activity against Candida albicans ATCC 10,231 and the lowest against Pseudomonas aeruginosa ATCC 9027. CuNPs from the S4c strain demonstrated the highest activity against Escherichia coli ATCC 10,231 and the lowest activity against Klebsiella pneumonia ATCC 13,883.ConclusionThe present work focused on increasing the CuNPs production by two isolates, Niallia circulans G9 and Paenibacillus sp. S4c, which were then characterized alongside. The used analytics and chemical composition techniques validated the existence of CuONPs in the G9 and S4c biosynthesized nano cupper. CuNPs of S4c are smaller and have a more varied shape than those of G9 strain, according to TEM images. In terms of antibacterial activity, the biosynthesized CuNPs from G9 and S4c were found to be more effective against Candida albicans ATCC 10,231 and E. coli ATCC 10,231, respectively.

Development And Validation of UV Spectrophotometric Method for The Estimation pf Amlodipine Besylate in Bulk and Dosage Form

A rapid, simple, accurate, and specific UV Spectrophotometric method has been developed for the determination of Amlodipine Besylate in bulk and dosage form. The spectrophotometric detection was carried out at an absorption maximum of 239 nm using dil. HCl as a solvent. The detector response for the Amlodipine Besylate was linear over the selected concentration range 4-20 µg/ml with a correlation coefficient of 0.999 and equation for the regression curve was found to be y= 0.109x + 0.006. These methods can be adopted in the routine assay analysis of Amlodipine Besylate API and pharmaceutical dosage form.

Decoding the commutable first hyperpolarisability of keto–enol tautomer using DFT and AI-based soft computing method

ABSTRACT Non-linear optical (NLO) parameter of a series of donor–acceptor substituted N-salicylidene-4-benzenesulfonylaniline (SBSA) derivatives with a contrast of first hyperpolarisability has been investigated using density functional-based theory. The derivative of SBSA with both the donor and acceptor substitution (NMe2-SBSA-NO2) exhibits the highest first hyperpolarisability ( ∼ 3 × 103 a.u in gas phase) value. Frequency and solvent polarity responsive behaviours of first hyperpolarisability are utilised to demonstrate the variation of NLO as switchable electrical parameter. Each of the studied compounds displays very high NLO response at frequency corresponding to the absorption maxima of their electronic state. Likewise, the increase of solvent polarity induces a substantial increase of first hyperpolarisability. The computation of NLO responsive first hyperpolarisability by varying the frequency and solvent dielectric constant within a wide domain is very tedious and time-consuming. To overcome the lacuna, we implemented machine learning tools such as artificial neural networks (ANNs), fuzzy logic (FL) and adaptive neuro-fuzzy inference system (ANFIS) to predict the computation data of the NMe2-SBSA-NO2 and moderately good results were obtained using ANFIS as soft computing tool.

Exploring the potential of Nauclea latifolia for sustainable synthesis of ZnO nanoparticles: characterization and antibacterial assessment

The work presents a report on Zinc oxide nanoparticles (ZnO NPs) synthesized through a green approach using Nauclea latifolia fruit extracts, with a view to investigating the prepared nanoparticles for their antimicrobial activities. The ZnO NPs synthesized were characterized using various analytical instruments, including X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Ultraviolet-Visible (UV-Vis) spectroscopy, Dynamic Light Scattering (DLS), and Transmission Electron Microscopy (TEM). The instruments provided valuable information on the characteristics of the Zn ONPs. The antibacterial activities of the synthesized ZnO NPs were evaluated with Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The maximum absorption was observed at 379 nm. The average hydrodynamic size and the polydispersity index (PDI) were measured as 81.77 nm and 0.401, respectively. The nanomaterial has a hexagonal wurtzite structure, and the Zn–O bond was detected at 537 cm–1. The nanoparticles were in the nano range with sizes ranging from 10.02 nm to 28.50 nm. The N. latifolia fruit extract-mediated ZnO NPs showed excellent performance against the two bacteria at all concentrations of ZnO NPs. The highest inhibition zones for E. coli and S. aureus at 8 mg/L of ZnO NPs are 21 and 16 mm, respectively. This study provides valuable insights into an efficient, simple, and environmentally friendly route for synthesizing ZnO NPs with a potential application in the biomedical field.

Exploring the Subcellular Localization of Monascus Pigments Biosynthases: Preliminary Unraveling of the Compartmentalization Mechanism

Monascus pigments (MPs), a class of secondary metabolites produced by Monascus spp., can be classified into yellow, orange, and red MPs according to their differences in the wavelength of the maximum absorption. However, the biosynthetic sequence and cellular biosynthesis mechanism of different MPs components are still not yet completely clear in Monascus spp. In this study, the subcellular localization of five MPs synthases was investigated using fluorescent protein fusion expression. The results revealed that the proteins encoded by the MPs biosynthetic gene cluster were compartmentalized in various subcellular locations, including the mitochondrial polyketide synthase MrPigA, cytosolic enzymes consisting of the ketoreductase MrPigC, the oxidoreductase MrPigE, and the monooxygenase MrPigN, and the cell-wall-bound oxidoreductase MrPigF. Moreover, the correct localization of MrPigF to the cell wall was crucial for the synthesis of orange MPs. Lastly, we discussed the compartmentalized biosynthetic pathway of MPs. This study will not only be helpful in clarifying the biosynthetic sequence and biosynthesis mechanism of different MPs but also provides new insights into the cellular biosynthesis of secondary metabolites in filamentous fungi.

Photophysical and antitubercular studies on newly synthesised structurally architectured sulphonamide

This study presents the synthesis and characterisation of four mono-azo sulphonamide derivatives through diazo-coupling electrophilic substitution reactions. The structural analysis of the synthesised molecules was conducted utilising FT-IR, 1H-NMR and HR-MS techniques. Absorption and fluorescence maxima of the synthesised molecules were determined across solvents of varying polarity to explore Solvatochromic behaviour. Density functional theory was employed to elucidate electronic and optical properties, including the computation of HOMO–LUMO energies using Gaussian 09W software, with comparisons to experimental data. Molecular electrostatic potential 3D plots identified electrophilic and nucleophilic sites. Solvent interactions were evaluated using Kamlet–Abboud Taft and Catalan parameters. Further, global chemical reactivity descriptors were estimated to ascertain chemical reactivity of the molecules. Additionally, the effectiveness of the colourant anti-tubercular activity was evaluated using in vitro and molecular docking techniques. The biological activity results reveal that methyl-pyridone and barbituric acid coupled with sulphamethizole (SMP and SMB) displayed excellent anti-tubercular activity compared with the standard Gentamycin.

Facile Recycling of Waste Biomass for Preparation of Hierarchical Porous Carbon with High-Performance Electromagnetic Wave Absorption

Hierarchical-porous-structured materials have been widely used in the field of electromagnetic wave (EMW) absorption, playing a critical role in minimizing EMW interference and pollution. High-quality EMW absorbers, characterized by a lower thickness, lighter weight, wider absorption band, and stronger absorption capacity, have been instrumental in reducing damage and preventing malfunctions in the automotive and aviation industries. The utilization of discarded nut shells through recycling can not only alleviate environmental problems but relieve resource constraints. Herein, a facile method for the preparation of hierarchical porous biomass carbon derived from abandoned Xanthoceras Sorbifolium Bunge Shell (XSS) biomass was developed for high-performance EMW absorption. The porous structures of XSS biochar were studied by using different levels of the K2CO3 activator and simple carbonization. The effect of K2CO3 on the EMW parameters, including the complex permittivity, complex permeability, polarization relaxation, and impedance matching, was analyzed. The best EMW absorption performance of the XSS biochar was observed at a mass ratio of activator-to-biomass of 2:1. A minimum reflection loss (RLmin) of −38.9 dB was achieved at 9.12 GHz, and a maximum effective absorption bandwidth (EABmax) of up to 3.28 GHz (14.72~18.0 GHz) could be obtained at a 1.8 mm thickness. These results demonstrated that hierarchical porous XSS carbon was prepared successfully. Simultaneously, the prepared XSS biochar was confirmed as a potential and powerfully attractive EMW-absorbing material. The proposal also provided a simple strategy for the development of a green, low-cost, and sustainable biochar as a lightweight high-performance absorbing material.

Extraction and characterization of anthocyanin pigments from Iris flowers and metal complex formation

Exploring the chemical processes and factors influencing the stability of the blue color derived from anthocyanins is a crucial objective in agricultural and food chemistry research. The ability of these compounds to bind with metals could potentially stabilize anthocyanins extracted from plant-based foods or enable modifying their hues for application as natural food colorants. This study had two core objectives - first, to extract and identify the major anthocyanin pigments responsible for iris flower coloration. Second, to selectively complex purified iris anthocyanins with aluminum (Al3+) and copper (Cu2+) ions, probing the coordination chemistry underlying synthetic metalloanthocyanin formation. Fresh iris flowers were collected and anthocyanins extracted using an optimized acidic solution. After separation, anthocyanins were complexed with metals Al3+ and Cu2+ at pH 5–6 to understand better the evolution of blue and green colors in anthocyanin-metal chelates. Characterization of anthocyanins and their metal complexes utilized UV–visible spectrometry, colorimetry (L\\* a\\*b\\* values), FTIR spectroscopy, and LC-MS. Metal complexation of anthocyanins exhibited bathochromic shifts of visible absorption maxima from 538 to 584 nm for Al-complex and 538–700 nm for Cu-complex. Color changes were accompanied by decreased lightness (L\\*, from 87 to 81) and color coefficients a\\* (+5.4 to −6.8) and b\\* (−12.2 to −4.8). LC-MS analysis identified five major anthocyanin aglycones: cyanidin (Cyd, m/z 289), delphinidin (Dpd, m/z 305), petunidin (Ptd, m/z 229), malvidin (Mv, m/z 329) and pelargonidin (m/z 273), along with various glycosylated derivatives. This work successfully isolated key iris anthocyanin pigments and elucidated their metal chelation interactions underlying expanded floral color production, bridging knowledge gaps about this underexplored genus.

Enhancing instrumental sustainability: a spectrophotometric approach for quantifying iodate in nutritionally significant salts through the adaptation of the classical iodometry method

With the primary objective of transitioning from the classical iodometric method to an instrumental approach, preserving precision in the analytical process, this study presents the development of a spectrophotometric method for quantifying iodate (iodine equivalent) in nutritionally significant salts. Therefore, the wavelengths of maximum absorption of the I3- (350.8 nm) and I3-starch (574.1 nm) complexes were determined. The complexes demonstrated stability, as indicated by the respective molar extinction coefficient values (ε) obtained over the course of the reaction time (measured up to 1h, at 5-minute intervals, and at 28°C), for concentrations ranging from 7.81×10-6 to 1.25×10-4 mols/L of KIO3. A linear correlation between concentration and absorbance was established within the specified concentration range, with detection and quantification limits defined as 0.09 and 0.29 mg/L (350.8 nm) and 0.13 and 0.39 mg/L (574.1 nm), respectively, and calculated recovery of 102.9%. The reproducibility of the method was assessed by varying the analyst, the equipment, and the analysis day. Using the developed method, it became feasible to quantify the elemental iodine equivalent in three commercially available salts commonly employed for food purposes. When compared to the classical/traditional iodometric method, the spectrophotometric method for quantifying iodate in salts showcases sustainability with minimized solvent and reagent usage, reduced waste generation, shorter analysis time, and lower sample requirements, aligning with environmentally conscious analytical practices.

Reversible Photochromism of 4,4'-Disubstituted 2,2'-Bipyridine in the Presence of SO3.

We report an unusual photochromic behavior of 4,4'-disubstituted-2,2'-bipyridine. It was found that in the presence of a SO3 source and HCl, 2,2'-bipyridine-4,4'-dibutyl ester undergoes a color change from yellow to magenta in solution with maximum absorbance at 545 nm upon irradiation with 395 nm light. The photochromism is thermally reversible in solution. Different from the known bipyridine-based photoswitching pathways, the photo response does not involve any metal which form colored complexes or the formation of colored free radical cations like the photo-reduction of viologens. A combination of experimental and computational analysis was used to probe the mechanism. The results suggest the colored species to be a complex formed between N-oxide of the 2,2'-bipyridine-4,4'-dibutyl ester and SO2; the N-oxide and SO2 are formed from photoactivated oxidation of the bipyridine with SO3 serving as the oxygen source. This complex represents a new addition to the library of photoswitches that is easy to synthesize, reversible in solution, and of high fatigue resistance, making it a promising candidate for applications in photo-switchable materials and SO3 detection. We also demonstrated experimentally similar photochromic behaviors with 2,2'-bipyridine-containing polymers.

THE METHOD OF QUANTITATIVE DETERMINATION OF THE AMOUNT OF FLAVONOIDS IN THE FLOWERS OF GIANT CEPHALARIA

Giant cephalaria (Cephalaria gigantea (LEDEB.) BOBROV) is a powerful perennial whose height reaches two meters. This plant is found in Southern Europe, Western and Central Asia, as well as in North and South Africa. It is cultivated in the Botanical garden of Samara University. The extracts of giant cephalaria have been used in traditional medicine for many years due to their antimicrobial, antifungal, cytotoxic, antioxidant, antidiabetic and antipyretic activities, which may be due to various biologically active compounds. It is known that the leaves contain triterpenoids, phenolic carboxylic acids and their derivatives, flavonoids, and the flowers contain flavonoid compounds: luteolin, quercetin, cynaroside, quercimeritrin and gigantoside A. The article describes the development of a technique for quantifying of the amount of flavonoids in the flowers of giant cephalaria. Spectrophotometric analysis of water-alcohol extracts from giant cephalaria flowers allowed us to establish that the main contribution to the absorption curve of their UV-spectra in the presence of AlCl3 is made by flavonols having a free OH group at the C-3 position, and in the differential version, the maximum absorption of the tested solution is close to that of the standard sample of quercetin (428±2 nm). Optimal conditions for the extraction of flavonoids in giant cephalaria flowers were determined: extractant 70% ethyl alcohol; the ratio "raw material-extractant" – 1 : 50; extraction time – extraction in a boiling water bath for 60 minutes, the degree of grinding of raw materials – 2 mm, analytical wavelength – 426 nm. It was determined that the content of the total flavonoids calculated on quercetin in the flowers of giant cephalaria varies from 1.58±0.05% to 2.63±0.05%. The error of a single determination with a 95% confidence probability is ±1.75%. The obtained results were used in the development of the FS project for a new type of medicinal plant raw materials "Cephalaria giant flowers" for introduction into the State Pharmacopoeia of the Russian Federation.

Glucose derived carbon encapsulated boron nitride core-shell composites for efficient electromagnetic microwave absorption

Hexagonal boron nitride (h-BN) has the advantages of outstanding insulation, high thermal conductivity and excellent chemical stability, which promote the wide application of h-BN in thermal interface electronic packaging and other related fields. However, due to the poor dielectric loss ability of h-BN, which leads to its weak absorption capacity of electromagnetic waves (EMW), so it limits its practical application in related advantageous fields. In this paper, glucose-derived carbon-encapsulated BN core-shell composites (C@BN) were prepared by a simple hydrothermal reaction followed by high-temperature pyrolysis. The dielectric loss capacity of the C@BN was investigated by manipulating the concentration of glucose solution and pyrolysis temperature. Specifically, by adjusting the glucose derived carbon defect to induce polarization loss and impedance matching performance, so that more EMW entering the interior of the composite is absorbed and dissipated. The results show that C@BN obtained at 800 °C shows the best EMW absorption performance when the concentration of glucose solution is 3.6 wt%. The minimum reflection loss value (RLmin) is −43.5 dB and the maximum width effective absorption bandwidth (EABmax) of 6.72 GHz. Therefore, this study provides a reliable reference for the preparation of h-BN based EMW absorbing materials.

The development of methods for determination the total flavonoids in buds of Populus alba L.

White poplar (Populus alba L., family Saliaceae ) has a similar chemical composition with other species of the genus Populus L. and it can consider as a promising source of raw materials containing phenolic compounds, in particular flavonoids. The pharmacological activity of the buds of pharmacopeial species of genus Populus L., and also of the white poplar is caused by biologically active compounds, mainly of a phenolic nature, including flavonoids (pinostrobin, piriocembrin, quercetin, etc.), phenylpropanoids (caffeic acid, etc.) and simple phenols (salicin).. One of the most well-known biologically active compounds of white poplar is quercetin, for which an antihistamine, anti-inflammatory action has been demonstrated. Differential spectrophotometry carried out in accordance with the OFS was used as a research method.1.2.1.1.0003.15 "Spectrophotometry in the ultraviolet and visible regions". Spectral characteristics of water-alcohol extracts were evaluated on a Specord 40 spectrophotometer (Analytik Jena AG, Germany) in cuvettes with a layer thickness of 10 mm. It was determined that in all electronic spectra of the water-ethanolic extractions from the buds of the white poplar there are two absorption maxima in the area of 290 nm and 370 nm, due to flavanones and flavonols, respectively. It was established that in the electronic spectra of the water-ethanolic extractions from the buds of the white poplar, a significant bathochromic shift of the long-wavelength band in the presence of aluminum chloride is observed, which confirms the presence of flavonoids. Under the conditions of differential spectrophotometry UV spectrum of the water-ethanolic extractions from the buds of the white poplar, an absorption maximum is observed at wavelength of 430 nm, which indicates the expediency of using quercetin in the analysis technique, which has an absorption maximum at a wavelength of 430±2 nm. As a result of the study, the method has been developed for the quantitative determination of the amount of flavonoids in the buds of white poplar using differential spectrophotometry calculated on quercetin at an analytical wavelength of 430 nm. The optimal parameters of extraction of raw materials were determined: extractant – 90% ethyl alcohol, the ratio of "raw material-extractant" – 1:30, extraction time – 60 minutes. The content of the total flavonoids calculated on quercetin in the buds of the white poplar is varied from 0,45±0,02 % to 0.69 ± 0.03%

Absorption by a Layered Microbolometer Pixel’s Active Element

Microbolometer arrays, i.e., arrays of micro-scale pixels sensing temperature via resistance changes, have proven to be an effective basis for real-time imaging instrumentation in infrared as well as terahertz frequencies. In previous work, a design of THz and IR absorbing nano-laminates of dielectric and metal layers was studied. It was shown via numerical modeling that absorption may be maximized by appropriate choices of thickness, permittivity and conductivity. In this work, an analytical approach to the problem is formulated based on the standard recursive multiple reflection formulas for multi-layered planar structures. The results fully confirm and extend previous numerical work. A previous relationship between wavelength and silicon thickness for maximum absorption, derived numerically for specific parameter combinations, is now generalized in a parametric closed form. The method can be extended to include multiple lossy dielectric layers and may serve as a tool for optimizing the absorption characteristics of more complex layered absorbing structures. This could enhance the sensitivity of the detection scheme of interest, providing benefits in terms of cost, efficiency, precision, and adjustability.