Search Results (32,631)

Nucleobases play diverse structural and functional roles in biological systems. Understanding the fundamental properties of nucleobases is important for their applications as chemical probes of nucleic acid function. As the nucleobases are modified to tune their fluorescence or binding properties, their physical properties such as pK_a may also change. Unlike the canonical nucleobases, modified nucleobases are less well understood in terms of their acid-base properties. Previously, theoretical pK_a values of canonical, naturally modified, and aza-/deaza-modified nucleobases were determined. In this study, the theoretical pK_a values for 25 different fluorescent modified nucleobases (55 total pK_a values) were calculated by using an ab initio quantum mechanical method employing the B3LYP density functional with 6-31+G(d,p) basis set along with an implicit–explicit solvation model. The results of these computations are compared to known experimental pK_a values. The ability to estimate theoretical pK_a values will be beneficial for further development and applications of fluorescent nucleobases. Full article

Flexible polyurethane foam (FPUF) is widely used in buffer protection, biomedical, and wearable fields due to its light weight, high resilience, and adjustable mechanical properties. However, the traditional water foaming system is often accompanied by bottleneck problems such as cyclic fatigue attenuation, insufficient thermal stability, and surface hydrophilicity while achieving low density. In this study, a dense Si-O-Si cross-linked layer was in situ constructed on the surface of the foam by systematically regulating the water content of the foaming agent (1.5~2.5 wt%) and coupling with methyltrimethoxysilane (MTMS) chemical vapor deposition. Experiments show that the foam foamed with 2 wt% water content still maintains 0.0466 MPa compressive strength and 0.0532 MPa compressive modulus (modulus loss is only 16.6%) after 500 cycles of compression at 90% strain after MTMS deposition. MTMS modification drives the surface wettability to change from hydrophilic (70.4°) to hydrophobic (128.7°), and significantly improves thermal stability (the carbon residue rate at 800 °C increased to 25.5%, an increase of 59.4%). This study not only improves the resilience, but also endows the FPUF surface with hydrophobicity and thermal protection ability, which provides the feasibility for its wide application. Full article

Silver sulfide quantum dots (Ag₂S QDs) are promising nanomaterials for biomedical applications due to their near-infrared emission and biocompatibility. In this study, Ag₂S QDs were synthesized using bovine serum albumin (BSA) as a stabilizing and reducing agent to assess their potential in targeted photothermal therapy. The QDs showed an average size of 1.06 ± 0.38 nm by DLS and 4.42 nm by TEM. Conjugation to an anti-PSG1 monoclonal antibody was performed via EDC/Sulfo-NHS chemistry and confirmed by FTIR spectroscopy, a decrease in zeta potential, and a redshift in emission. The conjugate exhibited an average size of 22.82 ± 9.7 nm and a zeta potential of +85.7 mV, indicating high colloidal stability. Fluorescence studies showed that the conjugate emits at 590 nm when excited at 560 nm, whereas the BSA-Ag₂S QDs (non-conjugated) emit at 480 nm upon excitation at 400 nm, reflecting changes in optical properties due to conjugation. Thermal imaging under 808 nm laser irradiation revealed efficient photothermal conversion, with temperature increases up to 13.6 °C at 200 μg/mL and a conversion efficiency of 11.41 ± 0.04%. The conjugate was non-cytotoxic to fibroblasts but induced selective cytotoxicity in HeLa cells after laser exposure, with a selectivity index of 3.0. These findings suggest that Ag₂S-BSA QDs conjugated with anti-PSG1 represent promising candidates for further investigation in cancer nanotheranostics. 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

This work proposes using acoustic emission during a static tensile test to determine the stress characteristics of the initial phase of the destruction process of elements printed using the material extrusion (MEX) additive method at various printing parameters. The changed parameters were layer height, print orientation, filling ratio, and nozzle temperature. ABS material was chosen for printing. The experiment was carried out according to the Taguchi plan. The analysis of the results showed that changes in printing parameters significantly impact the mechanical properties of the tested elements. The parameter that had the greatest impact on strength was the filling ratio. Maximum tensile strength was achieved with the following printing parameters: 0.24 mm layer, 30°, 100% infill, 275 °C, concentric pattern. The results can be the basis for optimizing the additive printing process and improving the efficiency and reliability of manufactured components. The results of recorded acoustic emissions during strength tests allow the identification of stresses characteristic of the initial phase of the destruction process of the tested material. This phase is the elastic-visco-plastic transition, and the use of the AE method enables its detection 2–5 s earlier than the static tensile test. This allows us to determine the safe range of stresses when using the mentioned materials, which is particularly helpful in designing structures or spare parts. The test results showed that the critical stress for the investigated components is approximately 6 MPa, and exceeding this value is associated with the risk of unsafe operation. Full article

The dynamics of dense colloidal systems are not fully understood. In the study of these types of systems, computer simulations based on the so-called hard sphere model play a significant role. In the presented work, we consider a system of hard spheres of the same size but different mobilities (molecules with high mobility correspond to solvent molecules, while molecules with reduced mobility are colloid particles) at varying concentrations. For this purpose, a two-dimensional lattice and an thermal model of such systems was designed. In order to determine the properties of such systems, a Monte Carlo computer simulation was used, employing the Dynamic Lattice Liquid (DLL) algorithm. Our main aim was to determine how the dynamic behavior of the system in the short time affects the long-time behavior. For this purpose, we investigated the cross-ratios of the diffusion coefficients in the short and long time of the considered system elements. It was found that the reduction in the solvent mobility with increasing concentration of colloidal particles in a short time leads to a very similar reduction in the mobility of the colloid particles in a long time, but we do not observe such behavior in the case of the solvent, i.e., there is a decrease in the value of the solvent diffusion coefficient in the long time with the change in the concentration of colloid particles, but it is difficult to connect it in a simple way with the decrease in the diffusion coefficient in the short time. Full article

This study evaluated the effects of surface treatments and thermal aging on the surface properties and bonding performance of three CAD/CAM lithium disilicate ceramics: Amber Mill, Vita Suprinity, and IPS e.max CAD. A total of 150 specimens were divided into five groups: control, hydrofluoric acid etching, airborne-particle abrasion, and Er,Cr:YSGG laser irradiation at 2 W and 3 W. Half of the samples underwent thermocycling (10,000 cycles, 5–55 °C). Surface roughness, water contact angle, and microshear bond strength were measured, and failure modes were analyzed. Ceramic type and surface treatment significantly affected outcomes. Amber Mill generally exhibited higher roughness, while IPS e.max CAD achieved the greatest bond strength. Hydrofluoric acid etching consistently enhanced bonding in Vita Suprinity and IPS e.max CAD, whereas 2 W laser irradiation improved bond strength without notably changing roughness. In contrast, 3 W laser treatment increased contact angle, reducing wettability. Thermocycling raised bond strength in control and sandblasted groups but overall increased contact angle. Adhesive failures predominated, though cohesive and mixed failures became more common after aging. Overall, ceramic type, surface treatment, and thermal aging interactively influenced adhesion. Hydrofluoric acid etching remains the most effective treatment, while low-power laser irradiation offers a promising, less invasive alternative. Full article

Gulf War Illness (GWI) is a neuroinflammation- and immune-dysfunction-related chronic disease. Corticosteroids, a class of steroid hormones with potent anti-inflammatory and immunosuppressive properties, have been studied for their role in GWI pathophysiology. Eight corticosteroid effect studies were evaluated in this systematic review. Preclinical models showed exacerbation of neuroinflammation, oxidative stress, and epigenetic changes with exposure to CORT in addition to Gulf War neurotoxicants, which induced pro-inflammatory cytokine expression (Tumor Necrosis Factor Alpha (TNF-α), Interleukin-6 (IL-6), C-C motif chemokine ligand 2 (CCL2)). Such findings suggest that corticosteroids can exacerbate symptoms of GWI and need further clinical research to clarify their role in neuroinflammatory processes. Full article

Calafate berry, an ancient perennial shrub of South America (Chile and Argentina), produces a high antioxidant capacity berry with a high polyphenol (1344.2–6553 mg GAE/100 g d.w.) and anthocyanin (26.5–80 mg C-3-G/100 g d.w.) content. The beneficial effects of calafate berries on human health are related to the anti-inflammatory, hypoglycemic, anticancer, and antioxidant properties that the berries possess, which have been confirmed through evidence to date, primarily from in vitro, ex vivo, and animal studies. Several investigations have shown a relationship between the consumption of calafate and a reduction in the risk of contracting cardiovascular diseases (CVD). This was evident in changes in plasma level biomarkers related to CVD, such as thrombomodulin (−24%), adiponectin (+68%), sE-selectin (−34%), sICAM-1 (−24%) and proMMP-9 (−31%), and changes in the production of OH radicals in plasma (−17%) after calafate intake. Calafate may have an antithrombotic role that supports cardiovascular health by lowering the Atherogenic and Cardiovascular Risk Indices. Various authors indicate delphinidin-3-glucoside (384–386 mg/100 g) as the primary bioactive compound responsible for the beneficial properties of Calafate. Although some studies report calafate’s health benefits, scientific evidence, especially in humans, remains limited. Meanwhile, Chile is working to domesticate and cultivate calafate, aiming to turn it from a wild native berry into a sustainable crop for use in the antioxidants and nutraceuticals industry. The lack of human clinical trials emphasizes the need for future research to validate calafate’s health benefits berry. Full article

This scientific research examines the intricate dynamics of Maxwell nanofluid flow across a stretching surface with Stefan blowing impacts, with a particular focus on maritime thermal management applications. The analysis integrates multiple physical phenomena including magnetohydrodynamic forces, the energy dissipation phenomenon, and thermal density variations within Darcy porous media. Special attention is given to Stefan blowing’s role in modifying thermal and mass transfer boundary layers. We derive an enhanced mathematical formulation that couples Maxwell fluid properties with nanoparticle transport under combined magnetic and density-gradient conditions. Computational results demonstrate the crucial influence of viscous heating and blowing intensity on thermal performance, with direct implications for naval cooling applications. The reduced governing equations form a nonlinear system that requires robust numerical treatment. We implemented the shooting technique to solve this system, verifying its precision through systematic comparison with established benchmark solutions. The close correspondence between results confirms both the method’s reliability and our implementation’s accuracy. The primary results of this study indicate that raising the Stefan blowing and density parameters causes notable changes in the temperature and concentration fields. The Stefan blowing parameter enhances both temperature and concentration near the wall by affecting thermal diffusion and nanoparticle distribution. In contrast, the density parameter reduces these values because of increased fluid resistance. Full article

Pomegranate (Punica granatum L.) is a strategic crop for Mediterranean agriculture due to its adaptability to arid environments—an increasingly important trait in the context of climate change—and its rising market demand driven by nutritional and medicinal properties. To support breeding and conservation efforts, this study evaluated the genetic diversity and phenotypic traits of two Mediterranean germplasm collections from Elche (Spain) and Bari (Italy). A total of 184 accessions were analyzed using SSR markers and evaluated for key pomological and phenological traits, including fruit weight, skin and aril color, seed hardness, aril weight, titratable acidity, soluble solids content, and harvest time. Genetic analyses revealed high levels of diversity within and between collections, with clear population structure influenced by geographic origin. Phenotypic evaluation revealed considerable variation in agronomic and quality traits, and several accessions with notably desirable characteristics were identified. For example, Ovadan and Molla Nepes displayed very high soluble solids content (>19 °Bx), Sanrà Nero, Sanrà Rosso, and Tajikistan Dark Red exhibited titratable acidity exceeding 40 g/L citric acid, and De Marco reached aril weights of up to 0.60 g. The integration of molecular and morphological data provided valuable insights into the distinctiveness and breeding potential of the studied genotypes. Misclassifications were identified, as well as phenotypic differences attributable to environmental influences. These findings highlight the importance of characterizing regional germplasm to preserve local adaptations and support development of new cultivars adapted to changing environmental conditions. This work reinforces the role of European pomegranate collections as reservoirs of genetic resources for sustainable cultivation and future breeding programs. Full article

This study is based on an experiment and a molecular dynamics simulation to investigate the distribution states and property variation laws of crude oil in nanopores, aiming to provide theoretical support for efficient unconventional oil and gas development. Focus is placed on the distribution mechanisms of multicomponent crude oil in oil-wet siltstone (SiO₂) and dolomitic rock (dolomite, CaMg₃(CO₃)₄) nanopores, with comprehensive consideration of key factors including pore size, rock type, and CO₂ flooding on crude oil distribution at 353 K and 40 MPa. It is revealed that aromatic hydrocarbons (toluene) in multicomponent crude oil are preferentially adsorbed on pore walls due to π-π interactions, while n-hexane diffuses toward the pore center driven by hydrophobic effects. Pore size significantly affects the distribution states of crude oil: ordered adsorption structures form for n-hexane in 2 nm pores, whereas distributions become dispersed in 9 nm pores, with adsorption energy changing as pore size increases. Dolomite exhibits a significantly higher adsorption energy than SiO₂ due to surface roughness and calcium–magnesium ion crystal fields. CO₂ weakens the interaction between crude oil and pore walls through competitive adsorption and reduces viscosity via dissolution, promoting crude oil mobility. Nuclear magnetic resonance (NMR) experiments further verified the effect of CO₂ on crude oil stripping in pores. This study not only clarifies the collaborative adsorption mechanisms and displacement regulation laws of multi-component crude oil in nanopores but also provides a solid theoretical basis for CO₂ injection strategies in unconventional reservoir development. Full article

Background: Land use change fundamentally alters soil microbial communities and biochemical processes, yet the integrated effects on rhizosphere microbiome–metabolome networks remained poorly understood. Objective: This study investigated land uses as forest, grassland and intermediary edge shape the rhizosphere biochemical networks of naturally grown Barbarea vulgaris. Methods: Rhizosphere soils of Barbarea vulgaris were analysed for microbial community structure abundance, and metabolomic profile applying phospholipid fatty acid (PLFA) profiling and mass spectrometric untargeted metabolomics (GC–MS/MS and MALDI–TOF/TOF MS). These were coupled with co–inertia analysis to assess microbiome–metabolome interactions. Results: Microbial community analysis revealed significant effects of land use on bacterial community structure (G+/G−, p < 0.001). Untargeted metabolomics identified 248 metabolites, of which 161 were mapped to KEGG pathways. Amino acids and derivatives (21.1%) followed by organic acids (16.8%) were the most representative among identified metabolites. Pathway enrichment analysis revealed coordinated reprogramming of central carbon and nitrogen metabolism across land use gradients, particularly in the amino acid metabolism, TCA cycle, and glycolysis/gluconeogenesis pathways. Microbiome–metabolome coupling analysis revealed distinct correlation patterns between microbial phenotypes and metabolite classes, with forest environments showing the strongest biochemical network integration (RV = 0.91). Edge habitats presented intermediate signatures, supporting their role as transitional zones with unique biochemical properties. Conclusions: The environmental context fundamentally shapes rhizosphere biochemical network organization through coordinated shifts in bacterial community structure and metabolic pathway activity. These habitat-specific metabolic signatures suggest that land use change triggers adaptive biochemical responses that may influence plant performance and ecosystem functioning across environmental gradients. Full article

The purpose of this paper is to study the weldability of two specific steels, UNS S31803 (duplex) and UNS S 32760 (super duplex), by making heterogeneous butt joints using gas tungsten arc welding technology. These materials are widely used in applications that take advantage of their superior corrosion resistance, strength, or both, such as chemical plants, oil and gas equipment, offshore sector, marine and other high-chloride environments. Although the joining technique of DSS and SDSS steels is a well-established industrial method, there are several process parameters that can play a key role in the correct execution of welds and in their final achievable properties. Starting from this assumption, this paper investigates some specific aspects such as the influence of heat input and shielding gas composition on the joint’s microstructure and the consequent changes in the ferrite/austenite ratio, also after post-welding heat treatments. Effects on both mechanical and corrosion resistance properties of the alloys are addressed. Full article

The aim of this research was to examine the antibacterial activity of commercially available silver nanoparticles against foodborne bacteria and to evaluate the properties of pullulan films incorporating these nanoparticles, including their antibacterial activity and selected physical properties. First, the antibacterial activity of silver nanoparticles against foodborne bacteria was investigated. The following parameters were assessed to evaluate the antibacterial activity of silver nanoparticles: minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), percentage antibacterial activity, bacterial survival based on time–kill curves, leakage of DNA and intracellular proteins using spectrophotometric measurements, and changes in bacterial cell morphology using scanning and transmission electron microscopy (SEM and TEM). Pullulan films with silver nanoparticle content ranging from 2 to 32 µg/cm² were obtained. The films were evaluated for antibacterial activity and physical properties, including macroscopic and microstructural (SEM) observations, thickness, light barrier, and color. Silver nanoparticles at a concentration of 25 µg/mL achieved 100% inhibition of the test bacteria, with destruction of bacterial cells after 3 or 6 h of incubation, depending on the silver nanoparticle concentration. Incorporation of silver nanoparticles into pullulan films, even in lower amounts, resulted in an antibacterial effect. All films had a compact and uniform microstructure and were shiny and flexible. Analysis of variance showed a significant (p < 0.05) effect of the addition of silver nanoparticles on the thickness, transparency, and color of the films. The obtained pullulan films containing silver nanoparticles were characterized by strong inhibitory activity against foodborne bacteria, had a brown color of varying intensity, a uniform microstructure, a smooth surface, and were barriers to UV radiation and visible light. Full article