Search Results (9,042)

Natural saline–alkaline soils are widespread in Central Asia, yet microbial responses to salinity gradients and ionic composition remain poorly resolved. We profiled bacterial communities (16S rRNA V3–V4, Illumina MiSeq) in 20 topsoil (0–20 cm) samples from four regions of Kazakhstan spanning non-saline to highly saline conditions. Soil chemistry included pH, total mineralization (dry residue), and major ions (Na⁺, Cl⁻, SO₄²⁻, HCO₃⁻, Ca²⁺, Mg²⁺, K⁺). Alpha (Chao1, Shannon, observed ASVs) and beta diversity (Bray–Curtis; ANOSIM; PCoA) were evaluated across salinity classes. Soils were alkaline (pH 7.91–10.47) and covered a broad salinity range (256–26,312 mg/L), driven mainly by Na⁺ with chloride and/or sulfate. Alpha diversity remained stable across salinity classes, though dispersion increased under high salinity. Community composition differed significantly among classes (ANOSIM R = 0.428, p = 0.005), with partial PCoA separation and overlap, indicating gradual turnover along the salinity gradient. In contrast, fungal communities showed no significant response to salinity, with stable alpha and beta diversity across all samples and consistent dominance of Ascomycota. Communities were dominated by Actinomycetota (formerly Actinobacteriota), Bacteroidota, and Pseudomonadota (formerly Proteobacteria). Bacteroidota increased in highly saline soils (FDR q = 0.036), whereas Acidobacteriota decreased (FDR q = 0.052). Thermodesulfobacteriota (formerly Desulfobacterota) correlated positively with sulfate, and Cyanobacteriota negatively with chloride. Overall, Kazakhstan’s saline–alkaline soils show stable bacterial alpha diversity but moderate, ion-linked compositional shifts with enrichment of halotolerant taxa. Full article

The increasing demand for high-performance and multifunctional polymer materials has driven interest in improving the mechanical properties of polymer components produced through additive manufacturing. This study aims to systematically investigate and comparatively evaluate the effects of low-content nanofiller incorporation on the structural, thermal, and mechanical performance of PLA-based materials produced via fused deposition modeling (FDM), with a focus on identifying filler-dependent behavior under different loading conditions. In this study, polylactic acid (PLA) composites reinforced with 0.5 wt.% graphene (Gr) and 0.5 wt.% silver (Ag) nanoparticles, added separately, were produced using fused deposition modeling (FDM) and comparatively investigated. Each nanofiller was incorporated individually into PLA-based filaments, and standard test specimens were fabricated via 3D printing. Structural, thermal, and mechanical properties were evaluated using tensile, compressive, and three-point bending tests, along with SEM, EDS, XRD, FTIR, DSC, and TGA analyses. The results showed that pure PLA exhibited typical brittle behavior and a single-stage thermal degradation profile. The tensile strength of pure PLA was 41.93 MPa, and the flexural strength was 70.76 MPa. The addition of 0.5 wt.% graphene led to noticeable improvements, particularly in flexural properties, while only a minimal (almost negligible) increase was observed in tensile strength, with tensile strength increasing to 42.24 MPa (+0.74%) and flexural strength increasing to 110.78 MPa (+56.6%). In contrast, 0.5 wt.% Ag exhibited mixed and load-dependent mechanical behavior, with slight improvements in flexural strength but reductions in tensile and compressive properties, where tensile strength decreased to 22.13 MPa (−47.2%) while flexural strength increased to 112.06 MPa (+58.3%). Structural and thermal analyses indicated that both nanofillers did not significantly alter the PLA matrix chemically, while contributing to controlled changes in material properties primarily through physical interactions. The novelty of this work lies in the comparative evaluation of graphene and silver nanoparticle reinforcement at a fixed low loading level within FDM-processed PLA, combined with a comprehensive and correlated analysis of mechanical, structural, and thermal behavior on the same specimen sets, enabling a clearer understanding of filler-dependent performance mechanisms in additively manufactured nanocomposites. Overall, it was concluded that low-rate nanofiller additions, when properly dispersed, may lead to selective improvements in the performance of PLA-based composites depending on filler type and loading mode, and show potential for advanced engineering applications such as lightweight structural components, functional sensors, and additive-manufactured parts requiring tailored mechanical performance and multifunctionality. Full article

This study was conducted to explore how varying the concentration of nano-La₂O₃ particles in the plating bath influences the morphology, constitution, and corrosion resistance of Ni-B composite coatings deposited on N80 carbon steel via electroless plating. The novelty of this work lies in the systematic investigation on the co-deposition behavior and grain refinement mechanism of nano-La₂O₃ in electroless Ni-B system, which has been rarely reported in previous studies. The microstructure and chemical composition of the coatings were characterized through a combination of SEM, EDS, XPS and XRD analyses. SEM confirmed that a dense Ni-B/La₂O₃ composite coating was formed, with a uniform thickness of approximately 10 μm, and the nano-La₂O₃ particles were evenly distributed. XPS analysis verified the presence of B, C, O, Ni and La, while XRD analysis revealed a refinement in crystalline size due to the addition of the nanoparticles. The corrosion resistance enhancement mechanism is attributed to the triple synergistic effect: nano-La₂O₃ pins grain boundaries and refines Ni-B grains to the minimum average size of 12.943 nm at the optimal concentration of 8 g·L⁻¹; the refined grain structure promotes the formation of a continuous and dense Ni(OH)₂ passive film; the uniformly dispersed nanoparticles act as physical barriers to block the penetration of corrosive media. Electrochemical measurements demonstrated that this coating exhibited outstanding anti-corrosion performance, as confirmed by a remarkably positive corrosion potential (E_corr = −0.37189 V) and a minimal corrosion current density (I_corr = 3.7524 μA/cm²). The results conclusively show that nano-La₂O₃ reinforcement effectively enhances the corrosion protection performance of electroless Ni-B alloy coatings. Full article

Optimizing the structural stability of foundations is challenging in modern geotechnical engineering. This study investigated the mechanism of geocell-reinforced foundations through discrete element modeling based on transparent soil model tests. A three-dimensional particle flow code (PFC^3D) model was developed to investigate the micromechanical soil–geocell interactions in both unreinforced and geocell-reinforced foundations under strip loading. Particle displacement, contact force distribution, and structural deformation within the foundation system were analyzed to quantify the performance of geocell reinforcement. The results show that geocell inclusion enhances structural performance by 2.1 times compared to an unreinforced foundation, increasing the bearing capacity from 60.6 to 126.8 kPa at a defined bearing capacity criterion. The geocell walls act as rigid physical boundaries that microscopically intercept the lateral migration and horizontal extrusion of soil particles. The kinematic trajectories of soil particles beneath the loading plate are forced into a downward realignment, decreasing the displacement vector rotation angle from 42° in the unreinforced soil to 27° in the reinforced soil and effectively mitigating the heave of adjacent surfaces. Furthermore, the quasi-rigid three-dimensional network completely interrupts the continuous steep contact force chains inherent in unreinforced foundations. Concentrated vertical stresses are converted into horizontal components through interfacial friction and mechanical interlocking, resulting in the lateral redistribution of the applied load by a distance of approximately 0.06 m. The geocell–soil composite considered as a flexible raft foundation extends load dispersion and reduces average subsoil pressure. A coupled tension and compression stress state in the horizontal plane is developed within the geocell structure. Forces are channeled along rigid paths by elevated bending moments and stress concentrations at the cell junctions. These findings provide micromechanical insights into the performance of geocell-reinforced-foundation systems. Full article

This work aims to investigate the interfacial tension characteristics of alkyl carboxymethyl betaines dispersed at the crude oil/formation water interface. Four alkyl dimethyl carboxymethyl betaines and one alkyl diethyl carboxymethyl betaine were synthesized, then the effects of surfactant molecular structure, crude oil component, and inorganic salt composition of formation water on interfacial tensions were studied systematically. The results show that the synthesized octadecyl diethyl carboxymethyl betaine has the highest interfacial activity and exhibits superior anti-dilution performance. In the presence of polyacrylamide, this betaine also displays good anti-adsorption capability. With respect to crude oil components, the resin component, especially the petroleum acid and alkali components, play important roles in tension reduction. For formation water, its alkaline inorganic salts are crucial to obtain an ultra-low interfacial tension by its saponification effect on petroleum acid. The octadecyl diethyl carboxymethyl betaine also exhibits good temperature and salt resistance, but poor tolerance toward divalent cations owing to the consumption of alkaline inorganic salts. Moreover, it is found that there exists synergism between octadecyl diethyl carboxymethyl betaine and dodecylbenzene sulfonate which can further reduce the interfacial tension. The above findings are conducive to the selection of betaine surfactants in chemical flooding. Full article

New lacunary Keggin-type polyoxometalate salts with the formula Cs₅PMMo₁₁(H₂O)O₃₉ (M = Cu, Zn) were synthesized via the inorganic solution condensation method. X-ray diffraction and FT-IR spectroscopy confirmed the preservation of the Keggin structure. The surface morphology and elemental composition were characterized using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. Thermal analysis, performed by differential scanning calorimetry coupled with thermogravimetry, demonstrated a significant enhancement in thermal stability upon the incorporation of the transition metals into the heteropolyacid framework. Specifically, the substitution of protons by cesium and of molybdenum by copper or zinc positively influenced the crystallographic configuration of the salts, raising their thermal resistance (up to 526 °C). Furthermore, optical and dielectric measurements revealed promising electronic properties in the synthesized lacunary salts. Notably, the compound Cs₅PZnMo₁₁(H₂O)O₃₉ exhibited a substantially increased dielectric constant at low frequency, underscoring the synergistic effect of zinc addition on its dielectric performance. Full article

This study examined the chemical composition and quantitative source contributions of coarse (PM_10–2.5) and fine (PM_2.5) particles in ship-based PM₁₀ and PM_2.5 filter samples from 2020 to 2024 across the Yellow Sea. The observations were primarily conducted during the spring season, when the influence of continental air masses from East Asia is pronounced, and detailed analyses of water-soluble ions and elemental species were performed. In coarse particles, sea salt components (e.g., Na⁺ and Cl⁻) and soil-derived species (e.g., nss-Ca²⁺ and CO₃²⁻) were predominant, whereas fine particles were dominated by secondary inorganic species such as nss-SO₄²⁻, NO₃₋, and NH₄⁺. Source contributions were estimated using Dispersion Normalized Positive Matrix Factorization (DN-PMF), and eight common factors were identified, including sea salt, soil, secondary nitrate, secondary sulfate, oil combustion, biomass burning, marine biogenic emissions, and plant growth. Additionally, an industry factor was uniquely resolved in coarse particles, whereas a mobile source factor was identified in fine particles. In coarse particles, sea salt (30.9%) and soil (15.1%) were the major contributing sources, whereas fine particles were dominated by secondary nitrate (48.6%) and secondary sulfate (15.6%). Potential Source Contribution Function (PSCF) analysis indicated that the sea salt and oil combustion factors in coarse particles were associated with coastal regions of the Yellow Sea and the East China Sea, while the soil factor corresponded spatially with inland regions of northern China. In contrast, the secondary nitrate, secondary sulfate, and biomass burning factors in fine particles showed strong associations with inland regions of eastern China. Using size-resolved DN-PMF and five years of repeated observations over the same marine region, this study provides the first quantitative source apportionment analysis of interannual atmospheric composition variability and long-range transport affecting air quality over the Yellow Sea. Full article

In the present study, the development of a high-density polyethylene/polylactic acid/titanium dioxide (HDPE–PLA–TiO₂) composite proposed for pellet-based additive manufacturing and the evaluation of its thermal and mechanical behavior are presented and discussed. The study was designed to address the printability limitations of high-HDPE-content systems, particularly extrusion instability and weak interlayer adhesion. PLA was introduced to improve processing stability, while TiO₂ was incorporated as an inorganic filler. The selected formulation allowed the production of filaments, pellets, and 3D-printed specimens. Thermal analysis indicated the absence of significant mass loss below approximately 300 °C under the applied thermogravimetric/differential thermal analysis (TG/DTA) conditions, suggesting that no major mass-loss degradation occurred within the selected processing window. However, this result should be interpreted as macroscopic thermal stability and does not exclude possible molecular-level changes in PLA during processing. Tensile tests indicated strengths of 20–25 MPa for extruded filaments and 7.86–10.36 MPa for printed specimens, with an elastic modulus of approximately 2 GPa. Scanning Electron microscopy equipped with Energy Dispersive X-Ray Spectroscopy (SEM/EDS) observations revealed a heterogeneous fracture morphology with cavities, microcracks, fibrillar structures, and local Ti-rich regions, supporting the influence of morphology and filler distribution on the mechanical response of the printed specimens. The results indicate improved printability, adequate thermal behavior for the selected processing conditions, and moderate but reproducible tensile performance, highlighting the potential of this formulation for pellet-based additive manufacturing applications where processability and rigidity are more relevant than maximum tensile strength. Full article

Aiming at the characteristics of high viscosity and poor fluidity of high waxy ordinary heavy oil, a Janus silica-based nanosheet composite viscosity reducer was designed and prepared in this paper. The viscosity reducer was assembled by asymmetric Gemini viscosity reducer and silica nanosheets through dehydration condensation reaction, and its structure was verified by FT-IR, ¹HNMR, XPS and DLS. The viscosity reduction performance, emulsion stability, interfacial tension and flow performance of the viscosity reducer were systematically evaluated by taking heavy oil with wax content of 35.7% and viscosity of 237 mPa·s at 30 °C as the research object. The results showed that, at an oil-to-viscosity-reducer-solution volume ratio of 3:7 and a viscosity reducer mass fraction of 0.3%, the maximum viscosity reduction rate reached 94.5% at 30 °C, calculated relative to the viscosity of the dehydrated original heavy oil. The oil–water interfacial tension was significantly reduced, and the 24 h bleeding ratio, defined as the volume percentage of separated water relative to the initial aqueous phase volume, was only 7.3%, indicating good emulsion stability. The core flow experiment shows that the resistance coefficient is reduced to the lowest at 0.3% concentration, and the seepage capacity is significantly improved. The analysis of total hydrocarbon gas chromatography showed that the content of high-carbon wax components in the C₂₃-C₃₀ range decreased by 4.79 percentage points after treatment, indicating that the viscosity reducer preferentially interacted with high-carbon wax molecules and promoted wax-crystal dispersion, thereby weakening the three-dimensional wax-crystal network. The viscosity reducer has the synergistic effect of dispersing wax crystals, reducing interfacial tension and stabilizing emulsification, which provides a low-cost and high-performance technical approach for the efficient exploitation of high waxy ordinary heavy oil. Full article

Essential oils (EOs) are widely studied as natural antimicrobial and antioxidant agents in food systems. However, their high volatility, low water solubility, instability, phytotoxicity, and strong aroma often limit their consistent applicability for food preservation. This review critically examines the literature and synthesizes current essential oil stabilization and delivery strategies in food systems, integrated with a bibliometric analysis of Scopus-indexed literature published before June 2025. The bibliometric findings showed an expanding research field, supported by 543 authors and 54 journals, revealing the disciplinary diversity of research on essential oil-based preservation systems. In addition, the review highlights a significant focus of studies on nanoemulsions, encapsulation, and active packaging in essential oil applications. Interestingly, the study also reveals the emergence of non-contact, or vapor-phase, technologies with improved release management. Furthermore, the review shows that essential oils’ functionality depends not only on major bioactive compounds but also on chemical class, oxidative sensitivity, release behavior, interactions with the food matrix, and the delivery platform. Mechanistically, stabilization technologies such as emulsions, encapsulation, and coatings/films can improve the protection, dispersion, and release of essential oils; however, their effectiveness strongly relies on formulation variables, matrix composition, and the regulatory framework. Emerging platforms such as nanofibers, zeolites, and metal–organic frameworks offer promising routes for vapor-phase or non-contact delivery systems, ensuring improved release control, functionality, and sensory quality, but may be limited by their scalability and production cost. However, a major research gap identified by this review is the imbalance between extensive “in vitro” studies and limited studies on real food matrices, which impedes understanding of the impacts of food matrices and packaging materials on essential oil release kinetics, antimicrobial efficacy, and sensory quality. Therefore, future research should integrate real-food applications, consumer acceptability, shelf-life performance, release-kinetic modeling, and techno-economic analysis to advance essential-oil-based technologies in food systems. Full article

The development of age-appropriate pediatric dosage forms remains an important challenge, particularly for acid-labile drugs requiring gastro-resistant protection. Pantoprazole, a proton pump inhibitor, must be protected from gastric acid until intestinal absorption; however, conventional enteric-coated tablets may be difficult to use in younger children, while manipulation of dosage forms or mixing with food can compromise dose accuracy and drug release performance. Multiparticulate systems, such as minitablets, pellets, or granules, offer flexible dosing but may still require a suitable vehicle to improve acceptability, handling, and ease of swallowing. In this study, enteric-coated pantoprazole minitablets were developed and evaluated after dispersion in selected hydrogel vehicles intended to serve as standardized alternatives to food-based carriers. Hydrogels based on hypromellose (HPMC), carbomer (CAR), and sodium alginate (SA) were characterized in terms of pH, rheological properties, firmness, acid penetration, and their effect on pantoprazole release. Dissolution performance was assessed using both conventional pharmacopoeial testing and dynamic non-pharmacopoeial conditions. Low-concentration gels prepared from high-viscosity HPMC grades showed the most favorable performance, combining suitable spoonable consistency with limited impact on drug release. Among them, 5% HPMC 65SH4000 was particularly promising, as it did not markedly delay pantoprazole release in either pharmacopoeial or dynamic dissolution testing. CAR gels provided advantageous rheological properties, including high viscosity at rest and shear-thinning behavior, and allowed efficient pantoprazole release after transition to buffer conditions; however, their interaction with enteric-coated minitablets should be further optimized with respect to gel amount, concentration, and neutralization strategy. SA gel showed strong structural persistence and delayed release under pharmacopoeial conditions, although this effect was less pronounced in the dynamic model. Overall, the findings indicate that appropriately selected hydrogels may improve the practical use of pediatric multiparticulate formulations, but their composition, pH, rheology, and interaction with enteric coatings must be carefully evaluated. Full article

Aggregates comprise up to 95% of flexible pavement composition, critically influencing performance based on geological source and processing methods. In Pakistan, where approximately 264,175 km of roads carry 96% of inland freight, premium Margalla aggregates face increasing demand and depleting reserves, necessitating sustainable alternatives. This study comprehensively evaluates aggregates from five key quarries (Margalla, Malakand, Kohat, Swabi, and Besai) for highway suitability. Rigorous laboratory testing encompassed macro-level physical and mechanical properties and micro-characterization using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FTIR), alongside performance tests including Indirect Tensile Strength (ITS), rutting resistance, and fatigue analysis. Overall, Margalla aggregates exhibited the best performance, showing the lowest abrasion value (21%), highest Tensile Strength ratio (TSR) (82%), highest conditioned ITS (433.7 kPa), highest dynamic modulus (2120 MPa at 25 Hz), and the lowest rut depth (7.8 mm at 10,000 cycles). These superior properties are attributed to their favorable physical characteristics and high calcium content. Malakand and Kohat aggregates also demonstrated satisfactory performance, with TSR values of 79% and 76%, conditioned ITS values of 408.7 and 377.7 kPa, and rut depths of approximately 8.8 and 10.5 mm, respectively, indicating their suitability for medium-traffic pavements. In contrast, Swabi and Besai aggregates exhibited lower moisture resistance (TSR = 77% and 75%), lower conditioned ITS (355.7 and 337.7 kPa), and higher rut depths (~13.0 and 14.2 mm), making them less suitable for high-stress pavement layers. These findings support Malakand and Kohat aggregates as viable regional alternatives to Margalla. Full article

Flexible capacitive pressure sensors have garnered significant attention in wearable electronics and robotic tactile sensing due to their high flexibility and simple structure. However, non-uniform distribution of conductive fillers in composite dielectric layers often compromises dielectric stability and sensing performance. In this work, a Cu/PDMS composite dielectric layer was fabricated using ultrasonic-assisted homogenization to enhance Cu particle dispersion and suppress sedimentation. A theoretical model and finite element simulations were employed to investigate the effects of particle distribution on permittivity, capacitance, electric field, and current density. The results indicate that uniform Cu dispersion improves dielectric stability and mitigates local electric-field concentration. Compared with conventionally prepared sensors, the ultrasonically treated sensor demonstrated higher sensitivity, enhanced dielectric stability, and a broader working range. Specifically, the sensor achieved a sensitivity of 0.157 kPa⁻¹ within 0–1 kPa and maintained stable performance over 1000 loading cycles. These findings confirm that ultrasonic-assisted homogenization is an effective approach for improving the dielectric and sensing performance of flexible capacitive pressure sensors. Full article

FDO’s wide boiling range and complex composition hinder controlled synthesis of high-performance mesophase pitch. Here, FDO was separated into light, middle, and heavy narrow fractions by vacuum distillation. Multi-scale characterization traced molecular evolution and mesophase development. The light fraction consists of three-ring aromatics with short alkyl side chains and shows the lowest reactivity, yielding limited condensation and poor stacking with isotropic regions and dispersed spheres. The middle fraction contains four-ring aromatics with moderately extended chains, exhibiting enhanced reactivity and undergoing nucleation, growth, coalescence, and disintegration of mesophase spheres. However, insufficient volatiles restrict shear orientation, forming a mosaic texture. The heavy fraction has four-ring aromatics with the longest alkyl chains and the lowest substitution degree, giving the highest reactivity. During thermal cracking, long chains release abundant radicals and volatiles; directional escape generates shear, promoting rapid growth and ordered alignment of aromatic lamellae. At 440 °C for 12 h, this fraction yields high-quality mesophase pitch with small-domain texture, a low softening point (295 °C), and high anisotropic content (98.8%). The pitch shows excellent spinnability, and derived carbon fibers (tensile strength ~1.45 GPa, modulus ~151 GPa) outperform a commercial reference processed under identical conditions. This study reveals molecular-level regulation of mesophase evolution by narrow fraction structures. Full article

In this work, the catalytic effect of a mechanochemically synthesized Co–Fe metal–organic framework (Co–Fe-MOF) on the thermal decomposition behavior of composite ammonium perchlorate–aluminum (AP-Al) systems was studied. The structural and morphological properties of the synthesized catalyst were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results confirmed the formation of a highly dispersed Co–Fe-MOF structure with a heterogeneous surface morphology and uniformly distributed active regions, as observed by SEM. The thermal decomposition behavior of the composites based on AP was studied using differential scanning calorimetry (DSC) at different heating rates. The addition of Co–Fe-MOF significantly affected the thermal decomposition process, moving the main exothermic decomposition step towards lower temperatures. At 5 wt.% of catalyst, the decomposition temperature decreased from 438–467 °C to 358–398 °C. The kinetic parameters were evaluated using the Kissinger and Ozawa–Flynn–Wall methods. The activation energy decreased from around 191–200 kJ·mol⁻¹ for pure AP and 184–194 kJ·mol⁻¹ for the AP-Al system to 95–109 kJ·mol⁻¹ after the introduction of 5 wt.% of Co-Fe-MOF. The observed catalytic activity is associated with accelerated electron transfer processes involving the redox couples Co³⁺/Co²⁺ and Fe³⁺/Fe²⁺, which favor the decomposition of AP and the oxidation of aluminum. The results demonstrate that the mechanochemically synthesized Co–Fe-MOF is an effective catalyst to improve the thermokinetic performance of AP-based energetic systems. Full article