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In this work,four ginkgolide molecules (ginkgolides A,B,C and J) were selected as the research objects,and their structures and spectral properties were investigated by density functional theory method.Our results indicated that the molecular skeleton of ginkgolides has a relatively stable structures by changing the substituents on ginkgolides.Based on the optimized structures,we calculated the Infrared (IR),Raman,vibrational circular dichroism (VCD) spectral properties of four ginkgolide molecules.We found that the IR spectra of the four ginkgolide molecules have obvious difference at 1100 cm-1,and this peak is mainly the stretching vibration mode of the C-O-C bond in ginkgolides.For the Raman spectra,the stretching vibration of the hydroxyl group is located at3200 cm-1,where ginkgolides A,B and C split into two peaks,while ginkgolide J displays a somewhat wide vibrational peak.For the VCD spectra,we found that four ginkgolide molecules are distinctly different around 3800 cm-1. [ABSTRACT FROM AUTHOR]

Lu 2 O 3 scintillation ceramics doped with different concentrations of Eu3+ were prepared by SPS in a vacuum environment. The microstructural properties of the prepared ceramics were analyzed using XRD, SEM and EDS in details. Excited by the 395 nm, the Eu3+-doped samples display a prominent emission peak at 612 nm, corresponding to the transition 5D 0 →7F 2. The PL spectra across various concentrations identified 3 at.% as the optimal doping concentration. The temperature-dependent PL spectra reveal the activation energy of approximately 0.266 eV for the 3 % Eu3+-doped Lu 2 O 3 ceramic. Under 395 nm excitation, the lifetimes of xEu:Lu 2 O 3 (x = 0.01, 0.03, 0.05 and 0.07) ceramics were fitted to be 1.07 ms, 1.02 ms, 0.99 ms and 0.92 ms, respectively. The XEL spectra of Eu3+-doped samples are consistent with their PL spectra, aligning well with the sensitivity range of the detector. These results demonstrate that Eu3+:Lu 2 O 3 scintillation ceramics are ideal materials for scintillation detectors. [ABSTRACT FROM AUTHOR]

Marennine is the specific bluish pigment produced by the marine diatom Haslea ostrearia Gaillon (Simonsen), responsible for the greening of oysters in France's Atlantic coast. For decades, H. ostrearia was considered the only blue diatom and described as such. However, new blue Haslea species have been described recently, among which Haslea karadagensis Davidovich, Gastineau, and Mouget (Black Sea, Crimea, Ukraine); Haslea provincialis Gastineau, Hansen, and Mouget (Mediterranean Sea, southern France); Haslea silbo Gastineau, Hansen, and Mouget (West Atlantic Ocean, USA); and one not characterized yet, Haslea sp. nov., isolated in Tenerife (Spain). These species produce marennine-like pigments, for which little information is available yet. The present work aims at studying spectral characteristics of these pigments by UV–visible spectrometry, Raman spectrometry, infrared spectrometry, nuclear magnetic resonance, energy-dispersive X-ray spectroscopy, and cyclic voltammetry, and comparing them to those of marennine produced by H. ostrearia strains originating from the north Atlantic Ocean (western France and Macaronesia), and north Pacific Ocean (southwestern USA). Results show that marennine produced by H. ostrearia strains and marennine-like pigments produced by H. provincialis, H. silbo, and Haslea sp. nov. are quite similar regarding their polysaccharide skeleton, and absorption in the UV–visible, infrared, and Raman regions. The most different marennine-like pigment is produced by H. karadagensis, but all Haslea blue pigments studied so far belong to the same family of organic molecules. [ABSTRACT FROM AUTHOR]

The complex compound bis(2,4-dichlorobenzoato-O)bis(thiourea-S)zinc(II) has been prepared and characterized by elemental analysis, thermal analysis, IR spectroscopy, and single-crystal X-ray analysis. During the thermal decomposition in inert atmosphere, thiourea, dichlorobenzene and carbon dioxide are evolved. The solid intermediate was confirmed by IR spectroscopy, and the final product of the thermal decomposition was proven by powder diffractometry. The coordination environment of the zinc(II) atom is built up by two sulphur atoms from two thiourea ligands and two oxygen atoms from two monodentate 2,4-dichlorobenzoate anions to form a distorted tetrahedral coordination around the zinc(II) atom (chromophore ZnO2S2). The mode of the carboxylate binding was assigned from the IR spectrum using the magnitude of the separation between the carboxylate stretches (Δ), and it is in good agreement with the crystal structure. The structure is also stabilized with hydrogen bonds of N–H···O and N–H···Cl type. [ABSTRACT FROM AUTHOR]

The metal exchange reaction of Mg(II)-octa-(4-fluorophenyl)tetraazaporphyrin with Co(II), Cu(II), and Mn(II) chlorides in dimethylformamide has been studied by the spectrophotometric method. The kinetic parameters were calculated and the stoichiometric mechanism of the metal exchange reaction was established. The influence of the solvate salt nature and the tetrapyrrole macrocycle chemical modification on the kinetic parameters of the studied reaction was revealed. Using the metal exchange reaction of Mg(II)-octa-(4-fluorophenyl)tetraazaporphyrin with CoCl2 in dimethylformamide, Co(II)-octa-(4-fluorophenyl)tetraazaporphyrin was synthesized. Co(III)-octa-(4-fluorophenyl)tetraazaporphyrin was obtained by treating Co(II)-porphyrazine with a dimethylformamide-hydrochloric acid mixture. The processes of cobalt complexes oxidation and reduction in solvents of various natures were studied. [ABSTRACT FROM AUTHOR]

Sexual selection is an important evolutionary force and despite extensive research, understanding mate choice on naturally occurring trait variation remains an intriguing area of study. The correlation between mass, a trait associated with courter viability and common target for mate choice, and signals is particularly noteworthy. This study focuses on Schizocosa mccooki, the largest member of a wolf spider genus renowned for its diverse complex male courtship. Our objective was to understand the relationship of male mass and other courtship signals on female choice within this species. We conducted lab experiments involving random pairings of field caught males and females, recording vibratory courtship and its outcomes. Our findings revealed that S. mccooki courtship consisted of vibratory signals with two major components, thumps and raps. Male mass, overall courtship vigor, and thump duration were found to predict mating success. Interestingly, we found no correlation between temporal traits and mass suggesting independent information and an absence of trade‐offs between mass, courtship vigor, and signal component rates/durations. Instead, we found that heavier males tend to produce thumps with lower frequencies. The finding that male mass predicts mating success contrasts with patterns observed in other species in this well‐studied genus. By uncovering the mate choice patterns of S. mccooki, this study underscores the importance of comparative studies to understand the ways in which sexual selection drives diversification, even among closely related taxa. [ABSTRACT FROM AUTHOR]

The authors study the spectral behavior of D–π–A type styryl dye of the quinoline series in solvents of different natures. Pronounced solvatochromism and sensitivity to the medium's viscosity are discovered. Microcrystalline dye powder is studied using chromium-forsterite laser radiation with a wavelength of 1250 nm. The observed differences in second-order nonlinearity correlate with structural differences in analogous compounds, and with factors of organizing the supramolecular system in the crystal. [ABSTRACT FROM AUTHOR]

The reconstruction of global annual mean temperatures made by the PAGES 2k Consortium in 2019 represents one of the most influential sequences of global climate variability over the Common Era. However, it is still not clear how the reconstruction can be influenced by the selection of reconstruction methods and the selection of proxy records with different temporal resolutions over different regions. We adopt a widely used Composite-Plus-Scale method to elucidate the effects of the selection of the proxy records on temperature reconstruction. To ensure the uniformity of data, different types of proxy records spanning the past ∼2000 years from the PAGES 2k proxy network were used to investigate the potential effects of proxy selection in hemispheric and global temperature reconstructions during the past two millennia. The long-term trends, spectral characteristics, and volcanic responses of the annual temperatures were studied based on the reconstructions. Our results reveal a significant cooling trend in the global annual mean temperature using both tree-ring and non-tree-ring records during the 1–1850 CE period, and show that the cooling exhibits a stronger trend in the Southern Hemisphere (SH) than that in the Northern Hemisphere (NH). Yet, the long-term trends vary according to different combinations of proxy records. Different reconstructions based on different types of proxies also exhibit different features in terms of volcanic responses and spectral properties. Tree-ring-based temperature reconstructions show stronger cooling responses to tropical volcanic eruptions, while non-tree-ring-based reconstructions suggest less robust volcanic responses, which may be related to dating uncertainties and low temporal resolution of the proxies. Tree-ring width records tend to preserve a substantial proportion of high-frequency (<200 years) variability, whereas non-tree-ring proxies tend to capture a larger fraction of low-frequency (>200 years) variations. Efforts are needed to reduce uncertainties of the temperature reconstruction over the Common Era associated with the insufficient spatiotemporal coverage of the current proxy network, especially for the first millennium and for the SH and tropics, also to develop statistical methods and to improve the signal strength and constrain uncertainties in existing proxy records. [ABSTRACT FROM AUTHOR]

The properties of natural polyphenol curcumin in water solutions of cationic Gemini surfactants decamethoxin and ethonium, which have similar positively charged nitrogen hydrophilic head groups but different spacer sizes and lengths of hydrophobic tails have been investigated in a wide range of concentrations by using UV–Vis spectroscopy and quantum‐chemical calculations. It was found that curcumin dissolves in the organized micellar media of these surfactants in the enol tautomeric form and its solubility increases 400 times compared to water. The binding constants of curcumin with decamethoxin and ethonium were determined by the solubility method. Significant differences in the influence of premicellar concentrations of cationic Gemini surfactants on the solubility and tautomeric transformations of curcumin were revealed. In contrast to decamethoxin, ethonium at a concentration below the CMC promotes a significant increase in the solubility of curcumin and a shift in the tautomeric equilibrium towards the formation of its keto form. [ABSTRACT FROM AUTHOR]

Piperine (a naturally occurring alkaloid), is a biologically active natural product belonging to the alkaloid series of compounds. In this study, the spectral characterization of piperine isolated from black pepper has been performed using FT-IR, 1H-NMR, and 13C-NMR. To explain spectral features, we have calculated the vibrational frequencies of the optimized structure of piperine using the B3LYP/6-311 + G(d,p) level of theory and NMR spectra using the GIAO method. All vibrational modes of the title molecule have been assigned based on potential energy distribution. The calculated scaled wavenumbers and NMR chemical shifts show good agreement with the experimental FT-IR and NMR data, respectively. To assess the bioactivity of piperine, we have first performed molecular docking using the ITK receptor and subsequently, the molecular dynamics simulation of the resulting complex for 100 ns. The results suggest the potential of piperine for possible anti-inflammatory action. [ABSTRACT FROM AUTHOR]

The effective utilization of solar energy is an important development direction to realize the exploration of clean energy. Herein, a model of solar radiation–thermoelectric generation (TEG) system is established, which is composed of solar absorbing coating and TEG component. Five different microscopic structures of coating are designed and the spectral absorption properties are numerically analyzed with the finite‐difference time‐domain method. Then, the absorbed solar energy and produced open‐circuit voltage with different coating structures are compared, with the coupling calculation of temperature field and electromagnetic field achieved. Additionally, the effects of structural size parameters on the output voltage performance are discussed. It can be observed that the absorbing coating can effectively improve the performance of TEG component, and the multilayer structure with appropriate gold particle diameter chosen is an optimization research direction for more efficient energy conversion. [ABSTRACT FROM AUTHOR]

The discovery of new peptides and their derivatives is an outcome of ongoing efforts to identify a peptide with significant biological activity for effective usage as a possible therapeutic agent. Spinorphin peptides have been documented to exhibit numerous applications and features. In this study, biologically active peptide derivatives based on novel peptide analogues of spinorphin conjugated with 5,5′-dimethyl (Dm) and 5,5′-diphenyl (Ph) hydantoin derivatives have been successfully synthesized and characterized. Scanning electron microscopy (SEM) and spectral methods such as UV-Vis, FT-IR (Fourier Transform Infrared Spectroscopy), CD (Circular Dichroism), and fluorimetry were used to characterize the microstructure of the resulting compounds. The results revealed changes in peptide morphology as a result of the restructuring of the aminoacidic sequences and aromatic bonds, which is related to the formation of intermolecular hydrogen bonds between tyrosyl groups and the hydantoin moiety. Electrochemical and fluorescence approaches were used to determine some physicochemical parameters related to the biological behavior of the compounds. The biological properties of the spinorphin derivatives were evaluated in vivo for anticonvulsant activity against the psychomotor seizures at different doses of the studied peptides. Both spinorphin analog peptides with Ph and Dm groups showed activity against all three phases of the seizure in the intravenous Pentylenetetrazole Seizure (ivPTZ) test. This suggests that hydantoin residues do not play a crucial role in the structure of spinorphin compounds and in determining the potency to raise the seizure threshold. On the other hand, analogs with a phenytoin residue are active against the drug-resistant epilepsy test (6-Hz test). In addition, bioactivity analyses revealed that the new peptide analogues have the potential to be used as antimicrobial and antioxidant compounds. These findings suggest promising avenues for further research that may lead to the development of alternative medicines or applications in various fields beyond epilepsy treatment. [ABSTRACT FROM AUTHOR]

As a non-invasive tool, ultrasound waves can be applied to probe gaseous content of the drilling fluid in offshore oil-drilling operations. The approach is believed to improve sensitivity and accuracy of a gas-kick detection system. In this research, four types of bubble flow are designed to simulate undeveloped gas kicks, and their effects on changes of ultrasound waves are investigated. The bubbles are found to have changed power distribution of the sound waves that have been reflected by the bubbles and received by side sensors. The pattern of power spectrum changes around the master frequency is found to be closely related to the type of bubble flow. Such changes are grouped on the basis of cluster analysis, and it is found that bubble strings and bubble groups would produce substantially different effects and that bubble mergences would largely alter spectral property of the sound waves. By establishing relationship between power-change pattern of sound waves and the behavior of a bubble flow, the research is intended to seek a more predictive way of recognizing early-stage gas kicks for offshore oil-drilling practices. [ABSTRACT FROM AUTHOR]

The conditioning and spectral properties of the mass and stiffness matrices for acoustic wave problems are here investigated when isogeometric analysis (IGA) collocation methods in space and Newmark methods in time are employed. Theoretical estimates and extensive numerical results are reported for the eigenvalues and condition numbers of the acoustic mass and stiffness matrices in the reference square domain with Dirichlet, Neumann, and absorbing boundary conditions. This study focuses in particular on the spectral dependence on the polynomial degree p, mesh size h, regularity k, of the IGA discretization and on the time step size Δ t and parameter β of the Newmark method. Results on the sparsity of the matrices and the eigenvalue distribution with respect to the number of degrees of freedom d.o.f. and the number of nonzero entries nz are also reported. The results show that the spectral properties of the IGA collocation matrices are comparable with the available spectral estimates for IGA Galerkin matrices associated with the Poisson problem with Dirichlet boundary conditions, and in some cases, the IGA collocation results are better than the corresponding IGA Galerkin estimates, in particular for increasing p and maximal regularity k = p - 1 . [ABSTRACT FROM AUTHOR]

Maintaining the airtightness of building envelopes is critical to the energy efficiency of buildings, yet leak detection remains a significant challenge, particularly during building refurbishment. This study addresses the effectiveness of the acoustic beamforming measurement method in identifying leaks in building envelopes. For this reason, an in-field study employing the acoustic beamforming measurement method was conducted. The study involved testing over 30 rooms across three different multi-story office buildings of varying ages and heterogeneous envelope structures. Numerous leaks were located in the façades, which were subsequently visually confirmed or even verified with smoke sticks. The data, captured using an acoustic camera (a microphone ring array), revealed distinct spectra that indicate the method's potential for further research. The basic functionality and the significant potential of this methodology for localizing leakages in large buildings were proven. [ABSTRACT FROM AUTHOR]

Solvent and substitution effects on the UV/Vis spectroscopic and fluorescence behaviour of seven synthesized 3-substituted 4-hydroxycoumarin derivatives were tested. The tested compounds were dissolved in ethyl acetate, acetonitrile, and dimethyl sulfoxide. Absorption and emission spectra were recorded in the range of 200–800 nm. All tested 4-hydroxycoumarin derivatives showed good absorption in a wide range of 200–550 nm, depending on the properties of the substituents on the benzene ring of the cinnamoyl moiety and the type of solvent. In comparison to the unsubstituted analogue, compounds with an electron-donating group exhibited bathochromically shifted UV/Vis absorption and emission spectra. The highest fluorescence quantum yield was observed for compounds with dimethylamino and acetamido groups as substituents at the benzene ring. Considering that both substitution and solvent affect the absorption and emission spectra of the tested compounds, it can be concluded that judiciously selecting these parameters can improve their absorption and fluorescence properties, making them suitable for various analytical uses.

Marennine is the specific bluish pigment produced by the marine diatom Haslea ostrearia Gaillon (Simonsen), responsible for the greening of oysters in France’s Atlantic coast. For decades, H. ostrearia was considered the only blue diatom and described as such. However, new blue Haslea species have been described recently, among which Haslea karadagensis Davidovich, Gastineau, and Mouget (Black Sea, Crimea, Ukraine); Haslea provincialis Gastineau, Hansen, and Mouget (Mediterranean Sea, southern France); Haslea silbo Gastineau, Hansen, and Mouget (West Atlantic Ocean, USA); and one not characterized yet, Haslea sp. nov., isolated in Tenerife (Spain). These species produce marennine-like pigments, for which little information is available yet. The present work aims at studying spectral characteristics of these pigments by UV–visible spectrometry, Raman spectrometry, infrared spectrometry, nuclear magnetic resonance, energy-dispersive X-ray spectroscopy, and cyclic voltammetry, and comparing them to those of marennine produced by H. ostrearia strains originating from the north Atlantic Ocean (western France and Macaronesia), and north Pacific Ocean (southwestern USA). Results show that marennine produced by H. ostrearia strains and marennine-like pigments produced by H. provincialis, H. silbo, and Haslea sp. nov. are quite similar regarding their polysaccharide skeleton, and absorption in the UV–visible, infrared, and Raman regions. The most different marennine-like pigment is produced by H. karadagensis, but all Haslea blue pigments studied so far belong to the same family of organic molecules.

In this study, Nd x :(La 0.05 Lu 0.05 Gd 0.05 Y 0.05)Ca 0.8-x F 2.2+x (x = 0.0–0.012) high-entropy transparent ceramics were prepared by the vacuum hot pressing method. The crystal structure, microstructure, elemental distribution and spectral properties of Nd x :(La 0.05 Lu 0.05 Gd 0.05 Y 0.05)Ca 0.8-x F 2.2+x , as well as the impact of Nd3+ content on these properties was systematically examined. The material demonstrates high optical transparency, achieving a maximum on-line transmittance of nearly 90 % at 1200 nm, which is very close to the theoretical CaF 2 transmittance (92%–94 %). Porosity and grain size are identified as the primary scattering factors. The EDX analysis revealed that the prepared transparent ceramics exhibited a high level of density and uniform distribution of elements. The highest luminescence intensity is observed at a Nd3+ concentration of 1 at.%, the fluorescence lifetime decays relatively slowly with increasing concentration of doped Nd3+ ions. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, compact micro‐/nanofiber sensors with fast response and high resolution have become a hot field in sensing and nanotechnology. In addition to the unique properties of microfibers such as strong evanescent field, low optical loss, and easy integration, microfiber knot resonators further improve the sensing capability due to their resonance properties. The potential high‐quality factor allows higher sensing sensitivity and resolution, which is very attractive for optical sensing at the micro‐/nano scale. More application potential can be effectively stimulated by improving the structure shape or principle or combining with functional sensitive materials. This paper first introduces the preparation process and spectral characteristics of conventional microfiber knots and then focuses on three new types of devices for enhancing the sensing performance, namely material‐coated, shape‐improved, and principle‐extended, and briefly analyzes their spectral properties. In addition, the research progress and applications of these sensors are summarized. Finally, the existing problems in this field are analyzed, and the directions for further development are discussed and prospected. [ABSTRACT FROM AUTHOR]

In this paper, a new matrix splitting (NS) is given based on the coefficient matrix of the double saddle point problems, and a modified new matrix splitting (MNS) preconditioner is also proposed. Theoretical analysis proves that the iteration method produced by the MNS preconditioner is convergent with any positive parameters under assumed conditions and the eigenvalues of the MNS preconditioned matrix are located in a positive interval. Numerical examples verify the efficiency of the proposed preconditioner. [ABSTRACT FROM AUTHOR]

In this paper, we study oscillatory properties of a fourth-order differential equation and spectral properties of a corresponding differential operator. These properties are established by first proving a new second-order Hardy-type inequality, where the weights are the coefficients of the equation and the operator. This new inequality, in its turn, is established for functions satisfying certain boundary conditions that depend on the boundary behavior of one of its weights at infinity and at zero. [ABSTRACT FROM AUTHOR]

Mo13 is a magic number cluster of Mon and can effectively activate N2 in ammonia synthesis, but its ground-state structure is not determined. The possible stable isomers of Mo13 are obtained by using global searching method (genetic algorithm) and further optimized at the level of BP86/def2-TZVP. The results indicate that Mo13 prefers to adopt open or layer-type structures due to the stronger 4d-5 s orbital hybridization. The most stable structure of Mo13 is a seriously deformed icosahedron and it is nearly degenerated in energies with the isomer of cage-like one. Both these two isomers are with high stabilities, and thus the electronic structures, bonding characters, spectral properties, reactive activities and the external filed response for these two isomers are systematically explored. This work provides many important information for distinguishing these two isomers. [ABSTRACT FROM AUTHOR]

Mo13 is a magic number cluster of Mon and can effectively activate N2 in ammonia synthesis, but its ground-state structure is not determined. The possible stable isomers of Mo13 are obtained by using global searching method (genetic algorithm) and further optimized at the level of BP86/def2-TZVP. The results indicate that Mo13 prefers to adopt open or layer-type structures due to the stronger 4d-5 s orbital hybridization. The most stable structure of Mo13 is a seriously deformed icosahedron and it is nearly degenerated in energies with the isomer of cage-like one. Both these two isomers are with high stabilities, and thus the electronic structures, bonding characters, spectral properties, reactive activities and the external filed response for these two isomers are systematically explored. This work provides many important information for distinguishing these two isomers. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Xinyang Normal University Natural Science Edition is the property of Journal of Xinyang Normal University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We study the structure of thin films of benzotrifuroxan, 1,3,5-triamino-2,4,6-trinitrobenzene, and 1,1-diamino-2,2-dinitroethylene, obtained by gas-phase deposition on various substrates: aluminum, polyethylene terephthalate, imitation parchment, quartz glass, polymer resin, silicon, and sapphire. The gaseous products obtained by thermal vacuum sublimation are subjected to preliminary preparation. The molecular structure of the obtained thin films corresponds to the studied substances. The texture of the films is determined. Their morphology is determined by particles that have a columnar shape, nonequilibrium faceting, and a developed surface. X-ray diffractometry, Raman spectroscopy, IR spectroscopy, spectrophotometry in the visible, ultraviolet, and near-infrared regions, and optical and electron microscopy are used in the measurements. The surface topology and electronic properties of the obtained textured films are studied. [ABSTRACT FROM AUTHOR]

The discovery of new peptides and their derivatives is an outcome of ongoing efforts to identify a peptide with significant biological activity for effective usage as a possible therapeutic agent. Spinorphin peptides have been documented to exhibit numerous applications and features. In this study, biologically active peptide derivatives based on novel peptide analogues of spinorphin conjugated with 5,5′-dimethyl (Dm) and 5,5′-diphenyl (Ph) hydantoin derivatives have been successfully synthesized and characterized. Scanning electron microscopy (SEM) and spectral methods such as UV-Vis, FT-IR (Fourier Transform Infrared Spectroscopy), CD (Circular Dichroism), and fluorimetry were used to characterize the microstructure of the resulting compounds. The results revealed changes in peptide morphology as a result of the restructuring of the aminoacidic sequences and aromatic bonds, which is related to the formation of intermolecular hydrogen bonds between tyrosyl groups and the hydantoin moiety. Electrochemical and fluorescence approaches were used to determine some physicochemical parameters related to the biological behavior of the compounds. The biological properties of the spinorphin derivatives were evaluated in vivo for anticonvulsant activity against the psychomotor seizures at different doses of the studied peptides. Both spinorphin analog peptides with Ph and Dm groups showed activity against all three phases of the seizure in the intravenous Pentylenetetrazole Seizure (ivPTZ) test. This suggests that hydantoin residues do not play a crucial role in the structure of spinorphin compounds and in determining the potency to raise the seizure threshold. On the other hand, analogs with a phenytoin residue are active against the drug-resistant epilepsy test (6-Hz test). In addition, bioactivity analyses revealed that the new peptide analogues have the potential to be used as antimicrobial and antioxidant compounds. These findings suggest promising avenues for further research that may lead to the development of alternative medicines or applications in various fields beyond epilepsy treatment.

Let Ω⊂ℝm$$ \Omega \subset {\mathrm{\mathbb{R}}}^m $$ be a bounded regular domain, let ∂x_$$ {\partial}_{\underset{\_}{x}} $$ be the standard Dirac operator in ℝm$$ {\mathrm{\mathbb{R}}}^m $$, and let ℝ0,m$$ {\mathrm{\mathbb{R}}}_{0,m} $$ be the Clifford algebra constructed over the quadratic space ℝ0,m$$ {\mathrm{\mathbb{R}}}^{0,m} $$. For k∈{1,...,m}$$ k\in \left\{1,\dots, m\right\} $$ fixed, ℝ0,m(k)$$ {\mathrm{\mathbb{R}}}_{0,m}^{(k)} $$ denotes the space of k$$ k $$‐vectors in ℝ0,m$$ {\mathrm{\mathbb{R}}}_{0,m} $$. In the framework of Clifford analysis, we consider two boundary value problems for a second‐order elliptic system of partial differential equations of the form ∂x_Fk∂x_=fk$$ {\partial}_{\underset{\_}{x}}{F}_k{\partial}_{\underset{\_}{x}}={f}_k $$ in Ω$$ \Omega $$, where fk$$ {f}_k $$ is a smooth k$$ k $$‐vector valued function. The boundary conditions of the problems contain the inner and outer products of the k$$ k $$‐vector solution Fk$$ {F}_k $$ with both the Dirac operator and the normal vector to ∂Ω$$ \mathrm{\partial \Omega } $$, ensuring the well‐posedness for the problems. Investigation of the spectral properties of the sandwich operator ∂x_(.)∂x_$$ {\partial}_{\underset{\_}{x}}(.){\partial}_{\underset{\_}{x}} $$ is considered by using the Fredholm theory. Finally, it is shown that satisfactory problem‐solving properties, in general, fail when we replace the standard Dirac operator by those, obtained via unusual orthogonal bases of ℝm$$ {\mathrm{\mathbb{R}}}^m $$. [ABSTRACT FROM AUTHOR]

We study the Schrödinger operators H λ μ (K) , with K ∈ T 2 the fixed quasimomentum of the particles pair, associated with a system of two identical fermions on the two-dimensional lattice Z 2 with first and second nearest-neighboring-site interactions of magnitudes λ ∈ R and μ ∈ R , respectively. We establish a partition of the (λ , μ) − plane so that in each its connected component, the Schrödinger operator H λ μ (0) has a definite (fixed) number of eigenvalues, which are situated below the bottom of the essential spectrum and above its top. Moreover, we establish a sharp lower bound for the number of isolated eigenvalues of H λ μ (K) in each connected component. [ABSTRACT FROM AUTHOR]

This work focuses on the effect of external electric fields on NH3 . In order to get more credible results, the density functional theory (DIT) B3 PW91 method is chosen to achieve the following computational work. The ground states of NH 3 in different external electric fields ranging from 0 a. u. to 0. 04 a. u. are optimized by B3PW91 method with CC - PVQZ basis sets. The molecule conformation parameters and infrared spectra (IR) of NH3 under different external electric fields are calculate d, respectively. Furthermore, the effects of different external electric fields on the excited states of NH3 are investigated by TD - DFT. The molecule conformation parameters and charge distribution of NH3 strongly depend on the external electric field. The total energy (Er) decreases with the external electric field. In contrary, the dipole moment (μ) keeps increasing over investigative external electric field. The energy level of the lowest unoccupied molecular orbital (LUMO ) increases through the variation of the external electric field, but the energy level of the highest occupied molecular orbital (HOMO) is proved to decrease as the change of external electric field. The energy gap (Ee) is found to increase with the external electric field. Through investigating the E c of NH3, it has been found that the external electric fields have a big impact on the chemical reactivity of NH3 . Both location and intensity of IR characteristic peaks of NH3 also can be affected by the external electric field. The external electric field can be used to regulate the IR of molecule, and then it is convenient to capture the spectral information. In addition, both excitation energy and oscillator strength of NH3 can be easily influenced by the external electric fleld. Therefore, the excitation properties of NH3 can be regulated by the external electric field. [ABSTRACT FROM AUTHOR]

In this paper, we characterize a new second-order Hardy-type inequality and find a two-sided estimate for its least constant. As applications of this new inequality, we study oscillatory properties of a fourth-order differential equation and spectral properties of a corresponding differential operator. [ABSTRACT FROM AUTHOR]

3-(Pyridin-2-ylmethylene)isoindolin-1-one was synthesized by the reaction of phthalimide with 2-picoline in the presence of zinc oxide. Heating its mixture with an excess of phthalimide and zinc acetate leads to the formation of zinc 5-(2-pyridyl)tetrabenzoporphyrinate, which, upon treatment with acid, is converted to 5-(2-pyridyl)tetrabenzoporphyrin. The latter, when reacting with cobalt(II), copper(II), and iron(III) chlorides in DMF, forms the corresponding metal complexes. The composition and structure of the obtained compounds were confirmed by mass spectrometry, vibrational, 1H NMR, and electron spectroscopy. The results of quantum-chemical calculations of complexes by the DFT method are presented. It is found that the energy gap between the frontier orbitals correlates with the positions of the first bands in the electronic absorption spectra. All the synthesized tetrabenzoporphyrins exhibit catalytic activity in the electroreduction of oxygen, cobalt and copper complexes being the most active. [ABSTRACT FROM AUTHOR]

l,7-bis-(4-hydroxy-3-methoxyphenyl)-l,6-heptadiene-3,5- dione (curcumin, Cur) and mono- and mixed Zn(II) complexes based on it were synthesized using the improved method. It was established that curcumin forms metal chelates of the composition ZnCur2-2H2O and Zn(Cur)2-Phen with the zinc ion. Coordination of the curcumin ligand with the central atom is bidentate cyclic through the p-diketone group, and the ortho-methoxyphenol fragment of Cur does not participate in chelation. The fluorescent properties of all synthesized compounds were studied. It was shown that the complex formation of zinc with curcumin causes an increase in the relative intensity of fluorescence and a shift of the emission band to the long-wave region. This indicates both the complexation process and the sensitizing effect of the zinc ion. When phenatroline is added to the zinc(II) complex, the fluorescence emission maximum undergoes a bathochromic shift compared to the ZnCur2 monoligand complex, and the relative fluorescence intensity decreases by 2.5 times. The shift of the radiation maximum to the region of low energies is due to the coordination of the phenathroline molecule to metal ions; and the decrease in emission is due to the shielding ability of the phenathroline donor molecule in relation to the weaker curcumin donor, which increases the number of non-radiative energy losses caused by its inefficient transfer due to the large energy gap between the triplet levels of the ligands. [ABSTRACT FROM AUTHOR]

Background and Objectives: Knowledge of the optical and thermal human tissues properties is essential for optimizing laser therapy and optical diagnostics. Most studies are carried out at room temperature of the sample. At the same time, it is known that the optical properties of biological tissues depend on temperature even in the physiological temperature range, that is, in the range of normal functioning of the body. Accordingly, there is a possibility that the use of literature data will lead to an incorrect assessment of the conditions for the propagation of light through biological tissue in a living object. Incorrect data on the optical properties of biological tissues at physiological temperature can lead to unreliable results in medical optical diagnostics or therapy. Therefore, studies of the temperature dependences of the optical properties of biological objects are undoubtedly topical. This work shows the differences in the optical properties of rat muscle tissue before and after heating the samples to physiological temperature. Materials and Methods: The spectra of collimated transmission, total transmission and diffuse reflection of rat muscle tissue were recorded. The spectra were recorded at 25°C (room temperature) and 38–39°C (physiological temperature). For each measured point of the sample, the spectral dependences of the absorption coefficients, transport scattering coefficient, and anisotropy factor of the studied samples were calculated. Results and conclusion: It has been shown that the optical properties of muscle tissue differ for room and physiological temperatures. In this case, the absorption and scattering coefficients practically do not change. The main parameter that changes with temperature is the anisotropy factor. This change also leads to a change in the transport scattering coefficient.

This work investigates a dynamic solution of human–machine systems with human error and common-cause failure. By means of functional analysis, it is proved that the semigroup generated by the underlying operator converges exponentially to a projection operator by analyzing the spectral property of the underlying operator, and the asymptotic expressions of the system's time-dependent solutions are presented. We also provide numerical examples to illustrate the effects of different parameters on the system and the theoretical analysis's validity. [ABSTRACT FROM AUTHOR]

The synthesis of new fluorescent probes, based on biocompatible luminophors and exhibiting various specificities, is intensively developed worldwide. Many luminophors contain a hydrophobic group that limits their application for cell staining under vital conditions. Herein, we report the synthesis of two BODIPY molecules—BF2-meso-(4-butan/pentanamido-N-(((1S,5R)-6,6-dimethylbicyclo [3.1.1]hept-2-en-2-yl)methyl)-N,N-dimethylpropan-1-aminium)-3,3′,5,5′-tetramethyl-2,2′-dipyrromethene bromides—designed as 10, 11 with a spacer of either four or three CH2 groups in length, respectively. These molecules present conjugates of BODIPY luminophors with (+)-myrtenol via a quaternary ammonium group. Both terpene-BODIPY conjugates demonstrated high fluorescence efficiency in various solvents such as OctOH, DMSO and water, and were characterized by their stability at pH 1.65–9.18. The fusion of the myrtenol, a monocyclic terpene, to the BODIPY fluorophore in the meso-substituent facilitated their penetration into the filamentous fungi Fusarium solani, while impairing the binding of the latter with S. aureus, K. pneumoniae and P. aeruginosa. The additional quaternary ammonium group between the myrtenol and fluorophore moieties restored the bacterial cell-staining while it did not affect the staining of fungi. Finally, the BODIPY conjugate 11 was able to stain both Gram-positive and Gram-negative bacteria by its interaction with their cell wall (or the membrane), as well as penetrating into filamentous fungi F. solani and staining their mitochondria. [ABSTRACT FROM AUTHOR]

For solving the saddle point linear systems with three-by-three block structure, in this paper, based on the alternating positive semi-definite splitting (APSS) preconditioner developed by Aslani et al. (Filomat, 15:5181–5194, 2021), we presented a new preconditioner called simplified relaxed APSS (SRAPSS) preconditioner. Spectral properties of the SRAPSS preconditioned matrix are analyzed. Numerical experiments verify that the proposed preconditioner is effective compared with some existing preconditioners. [ABSTRACT FROM AUTHOR]

Two series of tristriazolotriazine (TTT) derivatives with different length of aliphatic substituents have been synthesised in order to study the influence of peripheral substitution on mesomorphism and fluorescent properties of these star-shaped compounds. Homologues with methoxy and alkyloxy substituents (series 1) are non-mesogenic, in contrast to homologues with two alkyloxy substituents (series 2) exhibiting columnar mesophase. The results obtained by quantum-chemical calculations for the monomers and dimers of non-mesogenic TTT series and their comparison with truxenone derivatives having identical substituents made it possible to establish the reasons that deprive series 1 of mesogenity. Compounds of both TTT series possess good solubility in organic solvents and capable of specific interactions with solvents in the ground and excited states. They form fluorescenting floating layers and thin films. An analysis of the fluorescence spectra showed a high potential for their application, in particular, in the field of molecular sensing and precise non-invasive control. [ABSTRACT FROM AUTHOR]

In this work, we mainly propose a generalized simplified Hermitian and skew-Hermitian splitting (GSHSS) preconditioner for solving double saddle point problems and the eigenvalue distribution of the GSHSS preconditioner is analyzed in detail. In addition, we also study the eigenvector distribution and the degree of the minimal polynomial of the preconditioned matrix. Finally, numerical experiments show the effectiveness of the proposed preconditioner. [ABSTRACT FROM AUTHOR]

Modern applications of polymer-dispersed liquid crystals (PDLC) made of liquid crystal droplets dispersed in polymer matrices continue to grow in popularity. They include privacy and smart windows, flexible diffusers, advanced displays, energy storage, and energy harvesting devices, to name a few. An electrically controlled switching between opaque and transparent states of PDLC films enables their numerous applications. An applied electric field reorients an average director of a liquid crystal droplet resulting in a gradual transition from an opaque to a transparent state. A fully transparent state is observed if the refractive index matching is achieved. As a rule, electro-optical characterization of polymer dispersed liquid crystals is performed using a laser. As a result, basic physical parameters such as switching times, contrast ratio, and transmittance are obtained for a single wavelength of light. Even though the spectral dependence of electro-optical properties of PDLC films was mentioned in several papers, systematic studies reporting the dependence of contrast ratio, transmittance, and switching curves of PDLC films on the wavelength of light are still missing. In this paper, electrically controlled spectral properties of PDLC films are reported. The obtained dependence of the contrast ratio and transmittance on the wavelength of light can be used for the optimization of electro-optical performance of polymer-dispersed liquid crystals. [ABSTRACT FROM AUTHOR]

Adsorption of curcumin on the fumed silica from water/ethanol solutions has been studied using UV–Vis spectroscopy and advanced quantum-chemical calculations. The adsorption value of curcumin increases with increasing the water content in ethanol solutions and linearly correlates with their dielectric constant. According to quantum chemical calculations, an increase in the polarity of the solvent leads to an increase in its polarizing effect on the curcumin molecule and, consequently, to a redistribution of the electron density. As a result, the electron-donating ability of the oxygen atom of the carbonyl group increases, which leads to a proportional increase in curcumin adsorption on the surface of fumed silica. The adsorption isotherm of curcumin belongs to the L4-type, which characterizes the transition from monomolecular to polymolecular adsorption, in this case, to the adsorption of curcumin aggregates formed in solutions at a concentration of ССur > 1.5 × 10−4 М. The value of the conditional molar extinction coefficient of adsorbed curcumin was determined (εS434 nm = 3.44 × 105 g mol−1 cm−1). The found spectral characteristics of adsorbed (λmax = 432–434 nm) and precipitated (λmax = 500 nm) curcumin were used as a criterion for distinguishing two types of curcumin in the solid phase of the sorbent. The revealed patterns of adsorption are important in the preparation of nanocomposites based on silica and curcumin. [ABSTRACT FROM AUTHOR]

Natural colloids (NCs) are heterogeneous mixtures of particles in the aquatic environments that are strongly influenced by land use and water quality between terrestrial and aquatic environments. However, the relevant study paid little attention to the difference among the waters with different sizes of particles (e.g., suspended particulate matter (SPM), NCs, and the truly soluble substances). In this study, the spectral properties of these different waters were investigated from different land-use types in the Yuan River basin, China. Results of the UV–visible absorption spectral showed that with the particle size increased, the aromaticity, chromophoric dissolved organic matter, and humification degree of organic matter increased, while the condensation degree decreased. Data analysis from the fluorescence indices indicated that the source and the autochthonous feature of the truly soluble substances differed from that of NCs and SPM, whereas the protein-like component was mainly combined with the relatively larger size of particles (i.e., SPM and NCs), especially the downstream. Although the spectral characteristics of the water samples were strongly influenced by the water quality (> 45%), the land-use type might be the real potential impactor. Furthermore, the influence of land-use type on the spectral properties differed between the large and small scale of the buffer strips and between the mainstream and the tributaries. And this effect was more significant on the fluorescence properties in the mainstream and the spectral properties for NCs than for SPM. The study helps to understand the biogeochemical effects of the waters with different particle sizes. [ABSTRACT FROM AUTHOR]

Graph coarsening is a widely used dimensionality reduction technique for approaching large-scale graph machine-learning problems. Given a large graph, graph coarsening aims to learn a smaller-tractable graph while preserving the properties of the originally given graph. Graph data consist of node features and graph matrix (e.g., adjacency and Laplacian). The existing graph coarsening methods ignore the node features and rely solely on a graph matrix to simplify graphs. In this paper, we introduce a novel optimization-based framework for graph dimensionality reduction. The proposed framework lies in the unification of graph learning and dimensionality reduction. It takes both the graph matrix and the node features as the input and learns the coarsen graph matrix and the coarsen feature matrix jointly while ensuring desired properties. The proposed optimization formulation is a multi-block non-convex optimization problem, which is solved efficiently by leveraging block majorization-minimization, log determinant, Dirichlet energy, and regularization frameworks. The proposed algorithms are provably convergent and practically amenable to numerous tasks. It is also established that the learned coarsened graph is ϵ 2 (0, 1) similar to the original graph. Extensive experiments elucidate the efficacy of the proposed framework for real-world applications. The code for all the experimental results is available at CODE. [ABSTRACT FROM AUTHOR]