Search Results (7,070)

The paper presents comprehensive and complementary studies of the thermophysical properties of functional composite structures. The term functional in this case means the study of the structure while maintaining its post-production imperfections, as opposed to the study of material samples prepared solely for this purpose. The paper presents the results of experimental studies, followed by an analysis of thermophysical properties characterizing heat accumulation and anisotropic heat transfer of two types of utility composites. Composites with an epoxy matrix and two types of reinforcement, glass and carbon fibers, were studied. The research program included micro- and macrostructural analysis and comprehensive thermogravimetric, microcalorimetric and thermal diffusivity measurements. In the studies of heat transfer phenomena, the directional dependence of properties was considered. Attention was focused on maintaining high temperature resolution of measurements, and the effect of repeated temperature exposure was also determined. The results of the research are the determined quantitative and qualitative characteristics, including the temperature dependence of a set of thermophysical properties of the tested materials. Key findings include higher thermal stability and a significant thermal anisotropy ratio in the graphite-reinforced polymer composite compared to the glass-reinforced polymer composite, which exhibited a lower onset decomposition temperature. The results offer crucial data for engineering calculations, structural analyses, and defining operational limits. Analysis of the results provides insight into possible design and operational problems of real structures in relation to model data. Full article

Bioabsorbable scaffolds from synthetic polyesters are widely used in the field of tissue engineering. However, their hydrophobic surface and lack of suitable functional groups are the main limitations related to cell attachment. The aim of this research was to modify the surface of polycaprolactone (PCL) scaffolds using a bioactive coating containing heparin bound via albumin spacer and platelet lysate over heparin. Porous scaffolds were produced by electrospinning from 10% PCL (w/w) solution in methylene chloride (25 kV voltage, 100 mm distance between electrodes and 4 mL/h feedrate), which demonstrated 5.5 ± 1.1 MPa Young’s modulus, 2.5 ± 0.4 MPa tensile strength and 321 ± 29% elongation at break. Bioactive coating does not change the structure and mechanical properties of the scaffolds. Treated scaffolds are biocompatible and have no cytotoxic effect in direct contact with cells. Functionalization also promotes the in vitro adhesion and proliferation of human adipose mesenchymal stromal cells. After 7 days of incubation, the PCL scaffold modified with the heparin–platelet lysate complex had a cell density of 185.6 ± 15.7 cells/mm² compared to 79.5 ± 7.8 cells/mm² for nontreated control. The intramuscular implantation of scaffolds revealed that immobilization of heparin alone prolongs the acute phase of the inflammatory reaction. However, subsequent treatment with platelet lysate minimizes the inflammatory reaction, slows the rate of implant absorption, and accelerates vascularization. The results obtained show that the developed bioactive coating improves the cellular properties of PCL electrospun scaffolds and can be used to form in vivo tissue-engineered constructs. Full article

Moringa oleifera leaves are a protein-rich source containing all essential amino acids and offering high nutritional value. Ultrasound-assisted extraction (UAE) has emerged as an efficient method to improve protein recovery while enhancing the structural and functional properties of plant proteins. This study aimed to improve protein extraction from M. oleifera leaves using UAE and to characterize the nutritional composition and gel-related properties of the resulting protein concentrate. Chosen conditions were a solubilization pH of 11.68, 20 min of ultrasound treatment, and precipitation at pH 4.5, resulting in an extraction yield of 79.90% and protein content of 53.97%. Moringa oleifera leaf flour (MOF) contained 29.38% protein, 37.98% dietary fiber, and high mineral levels (1751.85 mg/100 g of calcium; 512.55 mg/100 g of magnesium). Compared with MOF, the M. oleifera protein concentrate (MOPC) showed a 21.4% increase in essential amino acids, with leucine and lysine being the most abundant. Functionally, MOPC exhibited 24.26% solubility at pH 2, complete gelation at pH 8, 58.66% emulsifying capacity with 79.52% stability at pH 10, and 21.11% foaming capacity with 94.44% stability at pH 2. The gel-forming ability was the most promising characteristic, highlighting the potential of MOPC as a natural structuring agent in gel-based food systems and functional formulations. Full article

Fine powders of erbium niobate-tantalates ErNb_xTa_1−xO₄ (x = 0; 0.1; 0.3; 0.5; 0.7; 0.9; 1) have been synthesized by the liquid-phase method in this study. Ceramic samples have been prepared using conventional sintering from these powders. Rietveld refinement of XRD patterns of polycrystals determined the phase composition and clarified the parameters of the phase structure of ErNb_xTa_1−xO₄ solid solutions depending on the Nb/Ta ratio. The morphological features of the microstructure of erbium niobate-tantalate ceramics have been studied. Their mechanical properties, strength characteristics (Young’s modulus, microhardness) and critical stress intensity factor of the first kind K_IC have been estimated. The photoluminescent properties of ceramic solid solutions of erbium niobate-tantalates depending on the composition have been studied. Dark and photoinduced toxicity of finely dispersed ErNbO₄ powders have been studied in relation to Gram-positive, Gram-negative and spore-forming microorganisms. The best indicators of antibacterial activity of ErNbO₄ have been demonstrated in relation to Gram-positive cells of Micrococcus sp. The discovered properties open up the possibility of not only traditional use as functional materials, but also the use of these materials for disinfection of surfaces, water and biological tissues. Full article

Topological indices are closely related to the stability and physical properties (such as the boiling point) of chemical molecules. The permanental sum and Hosoya index are two topological indices that are strongly associated with molecular structure. In this paper, we present algorithms for the permanental sum and Hosoya index. As an application, we employ these two algorithms to calculate the permanental sum and Hosoya index of (3,6)-fullerene with $n(4\le n\le 44)$ vertices. These results provide a mathematical reference for the synthesis of small (3,6)-fullerenes. Full article

This paper presents an adaptive fuzzy filter applied to processing a signal from a voltage sensor fed to the input of an object in an automatic temperature control system with a PI controller. (1) The research goal was to develop an algorithm for processing the signal from an RMS voltage sensor, measured at the terminals of a heating element in a temperature control system with a PI controller, in a way that ensures good dynamic properties while maintaining an appropriate level of accuracy. (2) The paper presents a method for designing an adaptive fuzzy filter by synthesizing a first-order low-pass infinite impulse response (IIR) filter and a fuzzy model of the dependence of this filter parameter value on the modulus of the derivative of the measured quantity. The application of a model with a symmetric input and output structure and a modified fuzzy model with asymmetry resulting from the uneven distribution of modal values of singleton fuzzy sets at the output was shown. The innovation in the proposed solution is the use of a signal from a PI controller to determine the derivative module of the measured quantity and, using a fuzzy model, linking its instantaneous value with a digital filter parameter in the measurement chain with a sensor monitoring the signal at the input of the controlled object. It is demonstrated that the signal generated by the PI controller can be used in a control system to continuously determine the modulus of the time derivative of the signal measured at the input of the controlled object, also indicating the limitations of this method. The signal from the PI controller can also be used to select filter parameters. In such a situation, it can be treated as a reference signal representing the useful signal. The mean square error (MSE) was adopted as the criterion for matching the signal at the filter output to the reference signal. (3) Based on a comparative analysis of the results of using an adaptive fuzzy filter with a classic first-order IIR filter with an optimal parameter in the MSE sense, it was found that using a fuzzy filter yields better results, regardless of the structure of the fuzzy model used (symmetric or asymmetric). (4) The paper demonstrates that in the tested temperature control system, introducing a simple fuzzy model with one input characterized by three fuzzy sets, relating the modulus of the derivative of the signal developed by the PI controller to the value of the first-order IIR filter parameter, into the voltage sensor signal-processing algorithm gave significantly better results than using a first-order IIR filter with a constant optimal parameter in terms of MSE. The best results were obtained using a fuzzy model in which an intentional asymmetry in the modal values of the output fuzzy sets was introduced. Full article

Biosurfactants are amphipathic compounds produced by various microorganisms, including fungi and yeasts, with those produced by the latter being of particular interest as they are considered microorganisms of low or no sanitary risk. This article presents an analysis of the available information regarding the role these compounds play within the ecological habitat where yeasts inhabit, as well as their potential biotechnological applications in commercial areas. Some of the biological roles that biosurfactants play for their producing microorganisms are unknown and can be highly diverse, depending on the adaptive needs microorganisms have to survive the environmental conditions prevalent in their habitat. However, some of these roles that have been reported are related to nutrient availability, cellular communication, and competition, as well as surface colonization. The structures of biosurfactant molecules produced by yeasts are highly diverse, and so far, have been reported as sophorolipids, carbohydrate–protein–lipid complexes, carbohydrate–protein polymers, mixtures of lactones, and mannosylerythritol lipids. In addition to their properties as surfactants and/or emulsifiers, many of these molecules have also been reported to possess biological activities, including antimicrobial, antifungal, antitumoral, antioxidant, antiadhesive, antiviral, ultraviolet (UV)-protectant, anti-aging agent, moisturizing, and enzyme-activator/inhibitor properties. By understanding the functions that biosurfactants perform in nature, novel and efficient methods for their production can be proposed, as well as new applications in areas such as pharmaceuticals, food, and cosmetics. The latter is of particular interest due to the growing biosurfactant market and the processes that demand greater knowledge about their production, biological, and environmental interactions for their management and disposal. Full article

This study presents an innovative modification to the chemical bath deposition method for synthesizing zinc oxide thin films by incorporating a high-voltage electric field, with and without electrical polarity inversion, to influence film growth dynamics. Two configurations were developed to assess the effects of electric field strength, periodic inversion, air agitation, and solution pH on the morphological, structural, and optical properties of ZnO coatings. Morphology studies revealed that particle size, shape, and distribution were strongly dependent on synthesis parameters, with electric field and air injection enabling higher surface coverage and finer nanostructures. Crystalline structural analysis confirmed the formation of the wurtzite ZnO phase, with reduced interplanar spacing and crystallite size under electric fields, especially when polarity was inverted. Optical measurements showed a consistent increase in the band gap (blue shift) and reduced defect-related absorption when electric field is applied. These findings are evidence that controlled electric field application during chemical bath deposition enables precise tuning of ZnO film properties. Full article

The Ionian Sea plays a crucial role as a crossroads for various Mediterranean water masses, making it a significant factor in the seawater budgets, biogeochemistry, and biodiversity of the subbasins of the Mediterranean Sea. In recent years, numerous theories have been proposed in an effort to better understand the complex hydrography and dynamics of the Ionian. These theories primarily focus on the variability of the basin’s near-surface circulation, which is characterized by a recurring reversal that occurs over a period of 10–13 years. This variability is often attributed to internal processes and/or boundary forcing, as waters of Atlantic origin enter the basin from its western boundary. In this study, we utilize temperature–salinity profiles and absolute dynamic topography data provided by the Copernicus database to examine long-term changes in the vertical structure of the basin and their relationships with changes in the horizontal near-surface circulation. Our findings show that the vertical dependency of the density field of the basin undergoes significant fluctuations over interannual and decadal time scales, which induce important buoyancy changes throughout the water column and determine changes in the structure of the first baroclinic mode. However, no changes in the basin-averaged hydrographic structure can be related to the near-surface current reversals. These reversals are mainly associated with deformations of the main isopycnal surface, intended as the region of maximum buoyancy over the water column, suggesting that they do not impact the hydrographic properties of the various Ionian water masses. Instead, they alter their routes and relative volumes within different parts of the basin. Full article

Background: G-quadruplexes (G4s) are non-canonical higher-order nucleic acid structures that form at guanine-rich motifs, with features spanning both secondary and tertiary structural levels. These dynamic structures play pivotal roles in diverse cellular processes. Endogenous G4s (eG4s) function through their dynamically formed structures, prompting the hypothesis that their thermostability, as a key structural property, may critically influence their functionality. This study investigates the relationship between G4 stability and other functional genomic signals within eG4 regions and examines its broader impact on chromatin organization and transcriptional regulation. Methods: We developed a mapping strategy to associate in vitro-derived thermostability metrics and multi-omics functional signals with eG4 regions. A stability-centric analytical framework combining correlation analysis and causal inference using the Bayesian networks was applied to decipher causal relationships between G4 stability and the other related signals. We further analyzed the association between the stability of transcription start site (TSS)-proximal eG4s and the biological functions of their downstream genes. Results: Our analyses demonstrate that G4 thermostability exerts causal effects on epigenetic states and transcription factor binding, thereby influencing chromatin and transcription regulation. We further show distinct network architectures for G4-binding versus non-binding transcription factors. Additionally, we find that TSS-proximal eG4s are enriched in genes involved in core proliferation and stress-response pathways, suggesting that eG4s may serve as regulatory elements facilitating rapid stress responses through genome-wide coordination. Conclusions: These findings establish thermostability—though measured in vitro—as an intrinsic property that shapes eG4 functionality. Our study not only provides novel insights into the functional relevance of G4 thermostability but also introduces a generalizable framework for high-throughput G4 data interpretation, significantly advancing the functional decoding of eG4s across biological contexts. Full article

Traditional diets based on diverse edible plants are increasingly threatened by climate change, which exposes crops to abiotic and biotic stressors such as drought, soil salinity, UV radiation, microorganisms, and insect herbivory. Understanding how these conditions influence both the nutritional and nutraceutical profiles, as well as the availability of key compounds, is essential to preserve their functional value. Piper auritum Kunth, used in Mexican gastronomy, was selected to assess two abiotic stress scenarios: drought stress (DS) and salicylic acid (SA) to simulate plant defense against pathogens and/or predators. We evaluated proximate composition, dietary fiber, total phenolics, total flavonoids, antioxidant capacity, low molecular weight carbohydrates (LMWCs), monomeric composition, and essential oil volatiles. Additionally, the simulated gastrointestinal digestion (INFOGEST) with an additional rat small-intestine extract (RSIE) revealed that both SA and DS shifted sugar distribution, especially for soluble and structural pools. SA treatment correlated with synthesis of secondary metabolites, particularly oxygenated and hydrocarbon terpenes. Both abiotic stressors modulated LMWC release during digestion, altering the distribution of sugars such as raffinose and galacturonic acid, with potential prebiotic implications. Essential oil analysis revealed stress-specific shifts in volatile composition, particularly in safrole, β-caryophyllene, and related terpenes. Beyond individual compound changes, the combined evaluation of composition, antioxidant properties, and volatile profile provides a comprehensive view of how abiotic stress can reshape the functional potential of P. auritum. To our knowledge, this is the first report on LMWC relative abundance across INFOGEST stages for a quelite species and on the integrated effect of DS and SA on its chemical profile. These findings highlight the importance of including compound release and functional traits, alongside chemical characterization, in future assessments of traditional plants under climate-related stress to safeguard their contribution to sustainable diets. Full article

Skin diseases, affecting one-third of the population, are a growing global health problem. The complexity of skin architecture, along with diverse symptomatology and intricate pathogenesis of dermatological disorders, highlights the urgent need for novel therapeutic strategies. Effective treatment of impaired wound healing and chronic skin diseases, including atopic dermatitis and psoriasis, remains challenging. Phytoterapeutics are increasingly investigated for their dermatologic potential, with numerous natural products of established use. Proanthocyanidins (PACs), a subclass of polyphenolic compounds, renowned for their anti-inflammatory and antioxidant properties, are promising candidates for novel solutions. This review article synthesizes the recent 25 years of research on biomolecular mechanisms, pharmacological effects, and phytochemical aspects of PACs, in the context of treating inflammatory-related skin problems. The available data highlight pro-regenerative, pro-angiogenic, antioxidative, and anti-inflammatory effects of PACs in accelerating wound closure. Preclinical data suggest their potent ability to mitigate chronic skin inflammatory disorders, including psoriasis and atopic dermatitis. Moreover, their photoprotective properties translate to the prevention of UV-induced skin inflammation. However, critical knowledge gaps remain regarding clinical verification and structure-activity relationships of PACs as dermatologic agents. Further optimization of topical formulation systems for PACs is also pressingly needed. Bridging traditional phytotherapy with novel discoveries in molecular pharmacology and pharmaceutical technology could help to design innovative PAC-based approaches for treating inflammatory skin diseases and impaired wound healing. Full article

Human immunodeficiency virus type 2 (HIV-2) is a lentivirus closely related to HIV-1 but exhibits distinct molecular and clinical features that influence viral infectivity and efficacy of antiretroviral therapy. The HIV capsid is a critical structural component with multifaceted roles during infection and mediates some of the observed divergence between HIV-1 and HIV-2. Unlike HIV-1, study of the HIV-2 capsid is limited and standard protocols for the in vitro assembly of HIV-1 capsid protein (CA) lattice structures have not been successfully translated to the HIV-2 context. This work identifies effective approaches for the assembly of the HIV-2 CA lattice and leverages this to biochemically characterize HIV-2 CA assemblies and mutant phenotypes. Our findings elaborate on the sensitivity of HIV-2 CA to chemical conditions and reveal that it assembles into a more varied spectrum of particle morphologies compared to HIV-1. Utilizing these assemblies, we tested the hypothesis that HIV-1 and HIV-2 employ divergent mechanisms to stabilize CA oligomer forms and investigate the effects of non-conserved substitutions at the CA inter-protomer interfaces. This work advances our understanding of the key biochemical determinants of HIV-2 CA assembly that are distinct from HIV-1 and may contribute to their divergent virological properties. Full article

Many experienced isolation and restricted behaviors due to the rapid onset of the COVID-19 pandemic in 2020. Investigations related to the psychological factors such as stress along with the danger of spread and contamination are scarce. The COVID-19 stress scale (CSS) was developed in order to evaluate such stress and anxiety related to the COVID-19 pandemic. The current study investigated the psychometric properties of the CSS, using a survey to provide evidence towards its continued use as a scientifically sound measuring instrument for future acute health crises in a sample of 615 college students (78.80% female, 18.60% male, 1.30% trans male, 1.00% non-binary), with a mean age of 19.10 years. The study partially supported the original measure’s factor structure. The main modification suggests a five-factor structure and removal of items related to less frequently used methods of banking and postal mail. The authors provide suggestions for future validation directions, use of the CSS and development of stress response strategies for students. Full article

The recent discovery of two-dimensional Mg (2D-Mg) intercalation in GaN has attracted increasing attention, prompting fundamental questions regarding its structural stability and electronic properties. In this work, we employ first-principles calculations to investigate the structural and electronic effects of 2D-Mg intercalation in GaN. We identify the most energetically favorable intercalation ratio of Mg, reveal the critical role of Ga vacancies in restoring semiconducting behavior, and demonstrate that compressive strain further modulates the electronic structure. In particular, the configuration with 75% Mg intercalation and nearest-neighbor Ga vacancy under compressive strain exhibits significant band gap narrowing and enhanced Mg-related acceptor activity. These findings challenge long-standing assumptions about Mg clustering and establish a mechanistic framework based on intercalation, vacancy engineering, and strain control for the design of next-generation p-type GaN devices. Full article