Search Results (2,600)

Background/Objectives: This study aimed to investigate the influence of shade and thickness on the polymerization of SDR^® flow+, a low-viscosity bulk-fill composite, by assessing its degree of conversion (DC). Methods: An in vitro study was conducted using SDR^® flow+ composite resin. Specimens were prepared at two thicknesses (2 mm and 4 mm) and four shades (Universal, A1, A2, A3). Polymerization was performed using a high-intensity LED curing unit. The DC was assessed using Fourier-transform infrared spectroscopy (ATR-FTIR). Results: Both shade and thickness significantly influenced DC. Thicker specimens (4 mm) exhibited reduced polymerization compared to thinner specimens (2 mm). Darker shades, particularly A3, demonstrated the lowest DC values due to their higher chroma, which limits light penetration. In contrast, the Universal shade achieved higher DC values, even at increased depths, likely due to its greater translucency. Conclusions: Shade and thickness play a critical role in the polymerization of bulk-fill composites. Ensuring adequate polymerization is essential for the longevity of pediatric restorations. Further in vivo research is needed to confirm these findings and assess their clinical implications. Full article

This study aimed to optimize the inoculation dosage and fermentation duration to enhance the protein content and reduce soluble oligosaccharides in soybean meal using Aspergillus oryzae and assessed its performance in dog food extrusion. A 3 × 5 factorial design was used to determine the optimal fermentation conditions. These conditions were applied to ferment soybean meal in bulk for nutritional analysis. Finally, the impact of fermentation on extrusion processing was assessed by formulating and extruding four diets: SBM (30% soybean meal), AMF (30% soybean meal with 1% Amaferm^®—A. oryzae biomass), FSBM (30% fermented soybean meal), and SPI (18% soy protein isolate). Diets were extruded with a single-screw extruder, and physical characteristics of kibbles, particle size distribution, and viscosity of raw mixes were analyzed. The optimal fermentation conditions were 1 × 10⁴ spore/g substrate for 36 h, which increased the crude protein content by 4.63% DM, methionine and cysteine total content by 0.15% DM, and eliminated sucrose, while significantly reducing stachyose, raffinose, and verbascose (95.22, 87.37, and 41.82%, respectively). The extrusion results showed that FSBM had intermediate specific mechanical energy (SME), in-barrel moisture requirements, and sectional expansion index (198.7 kJ/kg, 28.2%, and 1.80, respectively) compared with SBM (83.7 kJ/kg, 34.5%, and 1.30, respectively) and SPI (305.3 kJ/kg, 33.5%, and 2.55, respectively). The FSBM also exhibited intermediate particle size distribution and the least raw mix viscosity. These findings demonstrate that A. oryzae fermentation enhances the nutrient profile of soybean meal while improving extrusion efficiency and kibble quality, supporting its potential use as a sustainable pet food ingredient. Full article

Biocatalysis is one of the oldest fields that has been used in industrial applications, with one of the earliest purposeful examples being the mass production of acetic acid from an immobilized Acinetobacter strain in the year 1815. Efficiency, specificity, reduced reaction times, lower overall costs, and environmental friendliness are some advantages biocatalysis has over conventional chemical synthesis, which has made biocatalysis increasingly used in industry. We highlight three necessary fields that are fundamental to advancing industrial biocatalysis, including biocatalyst engineering, solvent engineering, and mechanistic engineering. However, the fundamental mechanism of enzyme function is often overlooked or given less attention, which can limit the engineering process. In this review, we describe how mechanistic enzymology benefits industrial biocatalysis by elucidating key fundamental principles, including the k_cat and k_cat/K_m parameters. Mechanistic enzymology presents a unique field that provides in-depth insights into the molecular mechanisms of enzyme activity and includes areas such as reaction kinetics, catalytic mechanisms, structural analysis, substrate specificity, and protein dynamics. In line with the objective of protein engineering to optimize enzyme activity, we summarize a range of strategies reported in the literature aimed at improving the product release rate, the chemical step of catalysis, and the overall catalytic efficiency of enzymes. Further into this review, we delineate kinetic solvent viscosity effects (KSVEs) as a very efficient, cost-effective, and easy-to-perform method to probe different aspects of enzyme reaction mechanisms, including diffusion-dependent kinetic steps and rate-limiting steps. KSVEs are cost-effective because simple kinetic enzyme assays, such as the Michaelis–Menten kinetic approach, can be combined with them without the need for specialized and costly equipment. Other techniques in protein engineering and genetic engineering are also covered in this review. Additionally, we provide information on solvent systems in enzymatic reactions, details on immobilized biocatalysts, and common misconceptions that misguide enzyme design and optimization processes. Full article

A modular strategy for the molecular design of silicone-based antifoaming agents was developed by precisely controlling the architecture of poly (methylhydrosiloxane) (PMHS). Sixteen PMHS variants were synthesized by systematically varying the siloxane chain length (L1–L4), backbone composition (D₃T₁ vs. D₃₀T₁), and terminal group chemistry (H- vs. M-type). These structural modifications resulted in a broad range of Si-H functionalities, which were quantitatively analyzed and correlated with defoaming performance. The PMHS matrices were integrated with high-viscosity PDMS, a nonionic surfactant, and covalently grafted fumed silica—which was chemically matched to each PMHS backbone—to construct formulation-specific defoaming systems with enhanced interfacial compatibility and colloidal stability. Comprehensive physicochemical characterization via FT-IR, ¹H NMR, GPC, TGA, and surface tension analysis revealed a nonmonotonic relationship between Si-H content and defoaming efficiency. Formulations containing 0.1–0.3 wt% Si-H achieved peak performance, with suppression efficiencies up to 96.6% and surface tensions as low as 18.9 mN/m. Deviations from this optimal range impaired performance due to interfacial over-reactivity or reduced mobility. Furthermore, thermal stability and molecular weight distribution were found to be governed by repeat unit architecture and terminal group selection. Compared with conventional EO/PO-modified commercial defoamers, the PMHS-based systems exhibited markedly improved suppression durability and formulation stability in high-viscosity environments. These results establish a predictive structure–property framework for tailoring antifoaming agents and highlight PMHS-based formulations as advanced foam suppressors with improved functionality. This study provides actionable design criteria for high-performance silicone materials with strong potential for application in thermally and mechanically demanding environments such as coating, bioprocessing, and polymer manufacturing. Full article

Transpiration cooling that utilizes the phase change of a liquid coolant is recognized as an effective thermal protection technique for extreme environments. However, the introduction of phase change within the porous structure brings about challenges, such as vapor blockage, pressure fluctuations, and temperature inversion, which critically influence system reliability. This study conducts numerical analyses of coupled processes of heat transfer, flow, and phase change in transpiration cooling using a Two-Phase Mixture Model. The simulation incorporates a Local Thermal Non-Equilibrium approach to capture the distinct temperature fields of the solid and fluid phases, enabling accurate prediction of the thermal response within two-phase and single-phase regions. The results reveal that under low heat flux, dominant capillary action suppresses dry-out and expands the two-phase region. Conversely, high heat flux causes vaporization to overwhelm the capillary supply, forming a superheated vapor layer and constricting the two-phase zone. The analysis also explains a paradoxical pressure drop, where an initial increase in flow rate reduces pressure loss by suppressing the high-viscosity vapor phase. Furthermore, a local temperature inversion, where the fluid becomes hotter than the solid matrix, is identified and attributed to vapor counterflow and its subsequent condensation. Full article

This study investigates the combined influence of superabsorbent polymers (SAPs) with distinct absorption kinetics and extended mixing sequences on the rheological, mechanical, and transport properties of high-performance concrete (HPC). Two SAPs—an ionic acrylamide-co-acrylic acid copolymer (SAP-P) and a non-ionic acrylamide polymer (SAP-B)—were incorporated at an internal curing level of 100%. The impact of extended mixing times (3, 5, and 7 min) following SAP addition was systematically evaluated. Results showed that longer mixing durations led to increased superplasticizer demand and higher plastic viscosity due to continued water absorption by SAPs. However, yield stress remained relatively stable owing to the dispersing effect of the added superplasticizer. Both SAPs significantly enhanced the static yield stress and improved fresh stability, as evidenced by reduced surface settlement. Despite the rheological changes, mechanical properties—including compressive and flexural strengths and modulus of elasticity—were consistently improved, regardless of mixing duration. SAP incorporation also led to notable reductions in autogenous and drying shrinkage, as well as enhanced electrical resistivity, indicating better durability performance. These findings suggest that a 3 min extended mixing time is sufficient for effective SAP dispersion without compromising performance. Full article

This study investigated the immunonutritional potential of high-molecular-weight (Mw~85 kDa), non-degraded chitosan (NCS) and gamma-radiation-degraded, low-molecular-weight chitosan (RCS) incorporated into aquafeeds for Nile tilapia (Oreochromis niloticus). RCS was produced by γ-irradiation (10 kGy) in the presence of 0.25% (w/v) H₂O₂, yielding low-viscosity, colloidally stable nanoparticles with Mw ranging from 10 to 13 kDa. Five diets were formulated: a control, NCS at 0.50%, and RCS at 0.025%, 0.050%, and 0.075%. No adverse effects on growth were observed, confirming safety. Immune gene expression (e.g., ifng1, nfκb, tnf), antioxidant markers (e.g., reduced MDA, increased GSH and GR), and nonspecific humoral responses (lysozyme, IgM, and bactericidal activity) were significantly enhanced in the NCS-0.50, RCS-0.050, and RCS-0.075 groups. Notably, these benefits were achieved with RCS at 10-fold lower concentrations than NCS. Following challenge with Edwardsiella tarda, fish fed RCS-0.050 and RCS-0.075 diets exhibited the highest survival rates and relative percent survival, highlighting robust activation of innate and adaptive immunity alongside redox defense. These results support the use of low-Mw RCS as a biologically potent, cost-effective alternative to traditional high-Mw chitosan in functional aquafeeds. RCS-0.050 and RCS-0.075 show strong potential as immunonutritional agents to enhance fish health and disease resistance in aquaculture. Full article

The use of 3D printing holds significant promise to transform the construction industry by enabling automation and customization, although key challenges remain—particularly the control of fresh-state rheology. This study presents a novel formulation that combines potassium-rich biomass fly ash (BFAK) with an air-entraining plasticizer (APA) to optimize the rheological behavior, hydration kinetics, and structural performance of mortars tailored for extrusion-based 3D printing. The results demonstrate that BFAK enhances the yield stress and thixotropy increases, contributing to improved structural stability after extrusion. In parallel, the APA adjusts the viscosity and facilitates material flow through the nozzle. Isothermal calorimetry reveals that BFAK modifies the hydration kinetics, increasing the intensity and delaying the occurrence of the main hydration peak due to the formation of secondary sulfate phases such as Aphthitalite [(K₃Na(SO₄)₂)]. This behavior leads to an extended setting time, which can be modulated by APA to ensure a controlled processing window. Flowability tests show that BFAK reduces the spread diameter, improving cohesion without causing excessive dispersion. Calibration cylinder tests confirm that the formulation with 1.5% APA and 2% BFAK achieves the maximum printable height (35 cm), reflecting superior buildability and load-bearing capacity. These findings underscore the novelty of combining BFAK and APA as a strategy to overcome current rheological limitations in digital construction. The synergistic effect between both additives provides tailored fresh-state properties and structural reliability, advancing the development of a sustainable SMC and printable cementitious materials. Full article

Vibration-stimulated waterflooding (VS-WF) is a promising enhanced oil recovery (EOR) method, especially for reservoirs with high-viscosity or emulsified oil. This study explores the effect of low-frequency vibration (2 Hz and 5 Hz) on oil mobilization under constant pressure and flow rate, using both crude and emulsified oil samples. Vibration significantly improves recovery by inducing stick-slip flow, lowering the threshold pressure, and enhancing oil phase permeability while suppressing the water phase flow. Crude oil recovery increased by up to 24% under optimal vibration conditions, while emulsified oil showed smaller gains due to higher viscosity. Intermittent vibration achieved similar recovery rates to continuous vibration, but with reduced energy use. Statistical analysis revealed a strong correlation between pressure fluctuations and oil production in vibration-assisted tests, but no such relationship in non-vibration cases. These results provide insight into the mechanisms behind vibration-enhanced recovery, supported by analysis of pressure and flow rate responses during waterflooding. Full article

Lubricant condition analysis is a valuable diagnostic tool for assessing engine performance and ensuring the reliable operation of diesel engines. While traditional diagnostic techniques—such as Fourier transform infrared spectroscopy (FTIR)—are constrained by slow response times, high costs, and the need for specialized personnel. In contrast, dielectric spectroscopy, impedance analysis, and soft computing offer real-time, non-destructive, and cost-effective alternatives. This review examines recent advances in integrating these techniques to predict lubricant properties, evaluate wear conditions, and optimize maintenance scheduling. In particular, dielectric and impedance spectroscopies offer insights into electrical properties linked to oil degradation, such as changes in viscosity and the presence of wear particles. When combined with soft computing algorithms, these methods enhance data analysis, reduce reliance on expert interpretation, and improve predictive accuracy. The review also addresses challenges—including complex data interpretation, limited sample sizes, and the necessity for robust models to manage variability in real-world operations. Future research directions emphasize miniaturization, expanding the range of detectable contaminants, and incorporating multi-modal artificial intelligence to further bolster system robustness. Collectively, these innovations signal a shift from reactive to predictive maintenance strategies, with the potential to reduce costs, minimize downtime, and enhance overall engine reliability. This comprehensive review provides valuable insights for researchers, engineers, and maintenance professionals dedicated to advancing diesel engine lubricant monitoring. Full article

Conventional asphalt is prone to cracking in cold climates due to its poor flexibility and limited ability to regulate temperature. This study investigates the use of low-temperature microencapsulated phase-change materials (MPCMs) to improve both the thermal storage and low-temperature performance of asphalt. MPCMs were incorporated into asphalt through physical blending at various concentrations. The physical, thermal, and rheological properties of the asphalt were then systematically evaluated. Tests included penetration, softening point, ductility, thermogravimetric analysis (TGA), and dynamic shear rheometer (DSR). The addition of MPCMs increased penetration and ductility. It slightly reduced the softening point and viscosity. These changes suggest improved flexibility and workability at low temperatures. Rheological tests showed reductions in rutting and fatigue factors. This indicates better resistance to thermal and mechanical stresses. Bending Beam Rheometer (BBR) results further confirmed that MPCMs lowered creep stiffness and increased the m-value. These findings demonstrate improved crack resistance under cold conditions. Thermal cycling tests also showed that MPCMs delayed the cooling process and reduced temperature fluctuations. This highlights their potential to enhance both energy efficiency and the durability of asphalt pavements in cold regions. Full article

Bio-based polyurethane asphalt binder (PUAB) derived from castor oil (CO) is environmentally friendly and exhibits extended allowable construction time. However, CO imparts inherently poor mechanical performance to bio-based PUAB. To address this limitation, attapulgite (ATT) with fibrous nanostructures was incorporated. The effects of ATT on bio-based PUAB were systematically investigated, including cure kinetics, rotational viscosity (RV) evolution, phase-separation microstructures, dynamic mechanical properties, thermal stability, and mechanical performance. Experimental characterization employed Fourier transform infrared spectroscopy, Brookfield viscometry, laser scanning confocal microscopy, dynamic mechanical analysis, thermogravimetry, and tensile testing. ATT incorporation accelerated the polyaddition reaction conversion between isocyanate groups in polyurethane (PU) and hydroxyl groups in ATT. Paradoxically, it reduced RV during curing, prolonging allowable construction time proportionally with clay content. Additionally, ATT’s compatibilizing effect decreased bitumen particle size in PUAB, with scaling proportionally with clay loading. While enhancing thermal stability, ATT lowered the glass transition temperature and damping properties. Crucially, 1 wt% ATT increased tensile strength by 71% and toughness by 62%, while maintaining high elongation at break (>400%). The cost-effectiveness and significant reinforcement capability of ATT make it a promising candidate for producing high-performance bio-based PUAB composites. Full article

Ozone pollution decreases rice yield and quality in general, but how ozone stress changes grain-filling capacity is unclear. A chamber experiment was conducted to compare the effects of ozone exposure during the rice growth season on the grain-filling capacity and quality of spikelets located on the upper primary rachis (superior spikelets, SS) and the lower secondary rachis (inferior spikelets, IS). Ozone stress significantly decreased filled grain percentage by 41.4% and grain mass by 10.2% in IS, but had little effect on grain-filling capacity in SS. Consistent with the reduction in grain mass, ozone stress decreased grain volume, mainly due to reduced grain thickness, and IS was reduced more than SS. After removing the hull, brown rice obtained from ozone treatment exhibited higher proportions of immature and abnormal kernels, resulting in a substantially lower proportion of perfect kernels. Under ozone stress, the proportion of perfect kernels was only one-third in IS, compared with two-thirds in SS. Ozone stress affected the pasting properties of brown rice for both SS and IS, as shown by the decreased amylose content, and the increased maximum viscosity, minimum viscosity, final viscosity, setback, and peak time of the rapid visco analyzer profile. Out of fourteen traits related to nutritional quality of brown rice, only five showed significant increases under ozone stress, and they were the concentrations of albumin, prolamin, sulfur, copper, and manganese. The differential ozone responses between SS and IS were rather small for rice pasting properties and chemical compositions as shown by very few significant interactions between ozone and grain position. It is concluded that ozone stress during plant growth imposed more adverse effects on IS than SS in terms of grain-filling capacity and appearance quality, suggesting an enlarged asynchronous grain-filling pattern in rice panicles under ozone pollution. Strategies to improve the grain-filling capacity of IS are needed to mitigate ozone-induced damage to rice production. Full article

This study investigated how microparticle size affects natural convective heat transfer in high-viscosity suspensions. Suspensions were formulated using 0.5% xanthan gum and 3% stearic acid, with particle sizes ranging from 120 to 750 nm. Key thermal properties, including thermal conductivity (0.598–0.679 W/m·K), specific heat, and the volumetric thermal expansion coefficient (0.990–1.000/°C), were measured. Rheological analysis based on the Herschel–Bulkley model revealed that reducing the particle size increased the consistency index from 0.56 to 0.75 Pa·s, while reducing the flow index from 0.63 to 0.50. This indicates enhanced shear-thinning behavior. A Rayleigh–Bénard convection system revealed that suspensions containing smaller particles exhibited higher Rayleigh and Nusselt numbers under large temperature gradients. Nusselt numbers reached values of up to 100 at a temperature difference of 9 °C. Conversely, suspensions containing larger particles exhibited relatively higher Rayleigh and Nusselt numbers under smaller temperature differences. These results demonstrate that optimizing microparticle size can enhance the efficiency of heat transfer in high-viscosity suspensions depending on the applied thermal gradient. This has practical implications for improving heat transfer in food and other viscous systems where convection is limited. Full article

Deep margin elevation (DME) is a widely adopted technique for managing subgingival cervical proximal margins by repositioning them to a supragingival location. This approach enhances access, visibility, and control in these anatomically challenging areas. This narrative review aimed to evaluate current evidence on the indications, materials, clinical protocols, and outcomes of DME. A structured search was conducted in PubMed, the Cochrane Library and Scopus up to February 2025, using keywords such as “deep margin elevation”, “proximal box elevation” and “subgingival margin.” Clinical studies, in vitro investigations, relevant reviews and reports in English were included. A total of 59 articles were selected based on eligibility criteria. The hypothesis was that DME can serve as a reliable alternative to surgical crown lengthening in appropriate cases. A variety of materials have been investigated for use as the intermediate layer, with composite resins of varying viscosities and filler compositions being preferred due to their favorable long-term mechanical properties. DME may reduce the need for surgical intervention while maintaining periodontal health; however further randomized clinical trials are needed to clarify the material selection, establish long-term outcomes, and standardize clinical protocols. Understanding the indications, limitations, and protocol of DME is critical for achieving biologically sound and predictably functional restorations. Full article