Search Results (3,898)

In this paper, batch stirred-tank alcoholysis reactions of used and refined sunflower oils were performed with n-octyl, myristyl, cetyl, oleyl, and stearyl alcohols using immobilized lipases Novozym 435 and Lipozyme IM as catalysts. Alcohol conversions ranged from 74% to 94%, with slight differences between used frying sunflower oil and refined sunflower oil. The resulting wax esters were purified via stepwise column chromatography. The different regioselectivity of the biocatalysts led to distinct reaction pathways, and Novozym 435 proved to be the most effective enzyme, providing higher conversions and no detectable by-products. This study demonstrates the valorization of waste frying oils into high-value wax esters through enzymatic alcoholysis, comparing two industrially relevant immobilized lipases and achieving high conversion across multiple long-chain alcohols. The results highlight a sustainable alternative to conventional chemical catalysis and extend biocatalytic applications beyond traditional biodiesel production. By incorporating waste lipids into value-added products, the overall sustainability and circularity of the system are improved, contributing to green and sustainable chemistry. Full article

Caprylic acid (CA) fractionation of serum is a simple and cost-effective method of producing high-quality immunoglobulins. While standardised procedures exist for CA purification of IgG for various animals, no published protocol exists for baboon IgG. This study aimed to optimise an efficient protocol for purifying IgG from baboon serum using CA through a stepwise one-factor-at-a-time (OFAT) approach. The effects of serum pH, CA concentration, stirring time and intensity, dialysis buffer, and lyophilisation were evaluated based on the protein content, with SDS-PAGE profiles and albumin–globulin ratios distinguishing IgG from residual albumin. Serum at pH 5.0 with 7% CA (v/v) produced the highest yield, minimising albumin while maximising IgG content. Lower pH (4.0–4.5) and CA (5–6%) reduced protein content, while a higher pH (5.5–6.0) and CA (8–15%) increased protein, but with elevated albumin and contaminants. Stirring serum vigorously at 1200 rpm for 60 min provided effective precipitation of non-IgG proteins. Lower intensities and shorter times resulted in higher albumin and residual proteins, while excessive stirring caused protein denaturation. Dialysis buffer composition had little impact, while lyophilisation significantly enhanced IgG concentration. The optimal protocol involved serum at pH 5.0, 7% CA (v/v), vigorous stirring (1200 rpm) for 60 min, and dialysis against sodium phosphate buffer (pH 7.4) followed by lyophilisation. The resulting IgG enrichment and purity were comparable to commercial-grade products. This study thus established optimal conditions for the purification of baboon IgG with CA, which could be used to support research in this animal model of immunology. Full article

Hexavalent chromium (Cr(VI)) is a high-priority environmental pollutant due to its strong oxidizing properties, which cause DNA damage and other severe health effects. Conventional detection methods are often costly and lack real-time monitoring capabilities, creating a strong demand for cost-effective, real-time biosensors that meet industrial requirements. In this study, we developed a novel biosensor for continuous Cr(VI) monitoring using a single-chamber microbial fuel cell (MFC). The biological element is an engineered Escherichia coli strain (ChrA-ChrB-E. coli), constructed by introducing Cr(VI)-resistant (ChrA) and Cr(VI)-reducing (ChrB) genes. The presence of Cr(VI) affects bacterial metabolism and electron transfer within the MFC, generating a measurable signal proportional to the contaminant’s concentration. The biosensor demonstrated robust performance and characteristics. The recombinant strain retained functional activity after 450 days of storage at −20 °C. The system exhibited high sensitivity and excellent linearity (R² ≥ 0.999) across a broad Cr(VI) concentration range of 0.015–200 mg/L. During continuous monitoring of chrome tanning and electroplating wastewater, measurements deviated by less than 2.33% from the standard diphenylcarbazide (DPC) method; electroplating deviation was further reduced to −0.69% with EDTA pretreatment. In fishery water, the deviation was higher (−7.12%) due to dissolved oxygen (DO) interference but was reduced to −0.75% after mechanical stirring to remove DO. The biofilm bacterial community remained highly stable over six months in both wastewater types, with the inoculated ChrA-ChrB-E. coli strain maintaining dominance (>99.6%). These results substantiate the feasibility of using this biosensor for continuous, online, real-time detection of Cr(VI) in actual wastewater environments. Full article

The temperature regulation of nonlinear continuous stirred tank reactor (CSTR) processes remains a challenging control problem due to strong nonlinearities, time-delay effects, and sensitivity to disturbances and parameter variations. Conventional proportional–integral–derivative (PID)-based control strategies often fail to provide the robustness and precision required under such conditions, motivating the use of more flexible controller structures and advanced optimization techniques. In this study, an enhanced joint-opposition artificial lemming algorithm (JOS-ALA) is proposed for the optimal tuning of a fractional-order PID (FOPID) controller applied to CSTR temperature control. The proposed JOS-ALA incorporates a joint opposite selection mechanism into the original ALA to improve population diversity, convergence stability, and resistance to local optima stagnation. A nonlinear CSTR model is linearized around a stable operating point, and the resulting model is employed for controller design and optimization. The FOPID controller parameters are tuned by minimizing a composite cost function that simultaneously accounts for tracking accuracy, overshoot suppression, and instantaneous error behavior. The effectiveness of the proposed approach is assessed through extensive simulation studies and benchmarked against state-of-the-art and high-performance metaheuristic optimizers, including ALA, electric eel foraging optimization (EEFO), linear population size reduction success-history based adaptive differential evolution (L-SHADE), and the improved artificial electric field algorithm (iAEFA). The benchmarking set is further extended with the success rate-based adaptive differential evolution variant (L-SRTDE) to broaden the comparative evaluation. Simulation results demonstrate that the JOS-ALA-based FOPID controller consistently achieves superior performance across multiple criteria. Specifically, it attains the lowest mean cost function value of 0.1959, eliminates overshoot, and yields a normalized steady-state error of 4.7290 × 10⁻⁴. In addition, faster transient response and improved robustness under external disturbances and measurement noise are observed when compared with competing methods. Statistical reliability of the observed performance differences is additionally examined using a Wilcoxon signed-rank test conducted over 25 independent runs. The resulting p-values confirm that the improvements achieved by the proposed approach are statistically significant at the 5% level across all pairwise algorithm comparisons. These findings indicate that the proposed JOS-ALA provides an effective and reliable optimization framework for high-precision temperature control in nonlinear CSTR systems and offers strong potential for broader application in complex process control problems. Full article

Cellulose nanofibrils (CNFs), with their high aspect ratio, have been widely used in various resin-based composites. To address the issues of easy agglomeration and poor interfacial compatibility of CNFs in hydrophobic acrylate photosensitive resins, this study adopted γ-methacryloyloxypropyltrimethoxysilane (KH570) for silane modification of CNFs, comparing heating–ultrasonication and heating–stirring methods. Mechanical properties were tested via LCD 3D printer to print splines. FTIR, XRD, and SEM verified successful modification, with the silicon substitution degree of heating–ultrasonication modification reaching 29.35%, significantly higher than heating–stirring (22.76%). Thermal analysis showed the main decomposition temperature increased from 400 °C to 420 °C, while DMA confirmed improved rigidity and glass transition temperature. Mechanical tests revealed a strength–toughness trade-off: the 1 wt% modified CNF composite exhibited a tensile strength of 45.17 MPa (9.41 MPa higher than unmodified CNFs at the same dosage), while a high dosage (3.5 wt%) enhanced toughness but reduced strength. The ultrasound-assisted silanization reaction proposed in this study optimizes the preparation process, achieving dual improvements in modification efficiency and dispersion. In terms of performance regulation, it reveals the quantitative control rules and trade-off characteristics of modified CNF content on the mechanical–thermal properties of the composites, providing a basis for performance customization. This study provides a feasible strategy for CNF modification in photopolymerizable 3D printing composites, expanding nanocellulose’s application in additive manufacturing. Full article

Nucleation remains one of the least understood steps during protein crystallization, although it strongly impacts product quality attributes, including total crystal numbers, final crystal size distributions, and thus downstream processing. In this work, the nucleation behavior of Lactobacillus brevis alcohol dehydrogenase (LbADH) wild type (WT) and five mutants (Q207D, Q126H, K32A, D54F, and T102E) is investigated in a stirred 7 mL crystallizer monitored by in situ multi-angle dynamic light scattering (MADLS). Nucleation was studied with highly pure homotetrameric LbADHs by establishing a crystallization, lyophilization, and re-solubilization protocol combined with size exclusion chromatography (SEC) and size exclusion high-performance liquid chromatography (SE-HPLC), yielding tetramer purities above 94% and removing low molecular weight impurities. During stirred batch crystallizations initiated by the addition of polyethyleneglycol 550 monomethyl ether (PEG 550 MME), SEC and SE-HPLC revealed decreasing tetramer peak areas but essentially constant peak apex positions, indicating that no long-lasting oligomeric intermediates accumulate at detectable levels. Time-resolved MADLS measurements using a custom-made flow-through cuvette in a bypass to the stirred crystallizer uncovered transient cluster populations. All protein variants exhibited an initial tetramer peak, followed by the formation of larger aggregates and a rapid rise in signal above a hydrodynamic diameter of 1000 nm, coinciding with the onset of macroscopic turbidity. A simple mesoscale nucleation model was formulated, yielding end-of-nucleation times, crystallized fractions, critical soluble concentrations, and apparent nucleation rate constants. The crystal contact mutations modulate both the timing and magnitude of the nucleation burst (rapid build-up of nuclei/cluster populations). The mutant Q207D showed strongly attenuated nucleation compared to the WT, whereas the other mutants (K32A, D54F, and particularly T102E) display markedly accelerated nucleation at nearly invariant critical concentrations. The combined workflow demonstrates how in situ MADLS, together with a tailored kinetic description, can provide mechanistic insight into protein nucleation in stirred batch crystallizers. Full article

The development of sustainable pigments from natural sources is gaining interest due to environmental concerns and the need for bio-based alternatives to synthetic dyes. This study investigates the synthesis of hybrid pigments by adsorbing anthocyanins—extracted from pomegranate agro-waste—onto halloysite (HA) nanotubes. A full factorial design was applied to evaluate the influence of pH and surfactant type (cetylpyridinium bromide and sodium dodecyl sulfate) on pigment colour and the thermal and structural stability of the hybrids. Adsorption was carried out in 400 mL dispersion baths containing 10 g of HA and 5% w/w anthocyanins. Surfactants (2% w/w) were added before the pigment, followed by 200 µL of silane. Dispersions were stirred at high speed for 1 h and then at 500 rpm for 23 h to ensure adsorption without premature desorption. Characterisation (TGA, XRD, FTIR, UV-Vis/NIR, SEM, EDX, BET) confirmed the preservation of HA structure and minimal changes in thermal behaviour. Pigment colour varied with synthesis conditions, especially pH: a higher pH increased brightness and yielded yellowish tones, while a lower pH resulted in reddish-blue hues with greater variability. The results confirm halloysite’s potential as a stable carrier for natural dyes and demonstrate that pH effectively tunes hybrid pigment colour. Full article

Paracetamol (PAR) was selected as an emerging micropollutant model to evaluate the effectiveness of the photo-Fenton process using natural Bandjéli ore (BO) as a heterogeneous source of iron. An aliquot of 1 mL of the activated product was introduced into 200 mL of an aqueous solution of paracetamol at a defined concentration. The tests were conducted in a double-jacketed glass photoreactor (0.2 L), continuously stirred and equipped with two UVA PL-L lamps (36 W, λ = 365 nm), with the temperature maintained at 20 °C and the pH around 2.4. The photo-Fenton process was applied with different initial paracetamol concentrations (10–50 mg/L), different ${\mathrm{H}}_2{\mathrm{O}}_2/\mathrm{P}\mathrm{A}\mathrm{R}$ initial molar ratios (10:1 and 5:1), and different ferric ion concentrations (2.84–4.73 mg/L). Under these conditions, complete disappearance of the parent compound (paracetamol) was achieved in less than 3 h for iron contents below 5 mg/L, in compliance with the discharge standards applicable in France and Togo. Inhibition tests with propan-2-ol highlighted the predominant role of hydroxyl radicals and the secondary involvement of superoxide radicals in the subsequent stages. Taken together, these results demonstrate that Bandjéli iron ore is an effective, sustainable, and economically advantageous alternative to commercial iron salts for implementing the photo-Fenton process in the decontamination of water polluted by organic micropollutants. Full article

Reliable multivariable control is critical for industrial sectors where processes exhibit severe nonlinearities and interactions. A Continuous Stirred Tank Reactor (CSTR) is a rigorous benchmark for testing control strategies addressing these complexities. This work first establishes a linear MIMO mathematical framework to define the specific structure of such interactive systems. Analysis via phase planes and steady-state analysis reveals low controllability, bistability, and strong coupling, leading to the collapse of traditional decoupled control schemes. To address these issues via multivariable control, we propose a centralized MIMO RST control structure synthesized via a Matrix Fraction Description (MFD) and the extended Bézout equation. Simulations for performance evaluation and comparison highlight the following key findings: (1) the centralized RST maintains stability and tracking precision in regions where decentralized RST loops fail; (2) it exhibits performance comparable to the Augmented State Pole Placement with Integral Action (ASPPIA) method and outperforms the standard Model-Based Predictive Control (MPC) baseline, particularly during critical equilibrium point transitions; and (3) it offers a robust yet computationally simple design that provides superior flexibility for pole placement, accommodating future identification-based models and adaptive tuning. These results validate our algebraic synthesis as a robust, computationally efficient solution for managing highly interactive nonlinear dynamics. Full article

The most important segment of the electric arc furnace (EAF) steelmaking process is the stirring and decarburization of the molten bath during the oxidation stage, with the bath temperature typically ranging from 1550 to 1600 °C. The coherent jet is a key factor influencing the stirring and decarburization of the molten bath. The factors affecting the impact capability of coherent jets have been widely studied, including the nozzle flow parameters and arrangement methods. However, there are few studies on the combustion chamber structure of the coherent jet oxygen lance. In order to study the effect of the combustion chamber structure on the characteristics of the coherent jet, a method combining numerical simulation and combustion experiments is used to study the flow fields of the coherent jet for a combustion chamber under different length and inclination angle conditions. The results show that the flow field characteristics of the coherent jet are influenced by the length and inclination angle of the combustion chamber. Compared with the coherent jet oxygen lance without a combustion chamber, the potential core length of the main oxygen jet under the short-distance horizontal combustion chamber condition is longer, but the potential core length of the main oxygen jet with the excessively long horizontal combustion chamber is shorter. The influence of the inclination angle on the potential core length of the main oxygen jet is complex. The influence mode is different depending on the length of the combustion chamber. Finally, it is found that the combined horizontal and inclined combustion chamber can achieve the best effect on prolonging the potential core length of the main oxygen jet. Full article

Particle size and size distribution are critical parameters that strongly influence the performance, reproducibility, and applicability of nanoparticles. In this work, we systematically investigated the effect of oscillation mode on the particle size and dispersion of SiO₂ nanoparticles synthesized via the Stöber method. Multiple commonly used laboratory mixing and oscillation modes—including stirring, horizontal shaking, vertical shaking, rotating, vertical shaking combined with rotating, water bath sonication, probe sonication, and static conditions—were comparatively evaluated. Particle size and size distribution were characterized by transmission electron microscopy and dynamic light scattering, and the polydispersity index (PDI) was quantitatively analyzed. The results demonstrate that stirring, horizontal shaking, vertical shaking, and rotating produce silica nanoparticles with comparable average sizes and consistently low PDI values within the investigated parameter range, indicating similar performance among these moderate and continuous oscillation modes under the studied conditions. In contrast, vertical shaking combined with rotating, water bath sonication, and probe sonication lead to larger particle sizes and broader size distributions, accompanied by elevated PDI values. Although static conditions yield smaller average particle sizes, the resulting particles exhibit the highest PDI, reflecting poor size uniformity. These findings provide practical process-level guidance for selecting appropriate oscillation modes to achieve reproducible and uniform silica nanoparticle synthesis in general laboratory settings. Full article

Metal matrix composites (MMCs) are one of the significant engineering materials for many industrial applications. The growing interest in MMCs stems from their strong mechanical properties, including their higher specific mechanical strength and excellent corrosion and wear resistance. From an industrial viewpoint, the ability of MMCs to undergo secondary processing is significant. This review aims to clarify the effects of cryorolling on the microstructure, mechanical properties and wear behavior of different aluminum-based MMCs. In particular, aluminum matrix composites (AMCs) produced through the stir-casting approach experience an additional cryorolling procedure to enhance their tensile mechanical strength and wear resistance. This hybrid manufacturing approach has shown promise in creating effective structural components. This review covers the production of ex situ aluminum-based composites formed by stir casting and then cryorolling. It also highlights how the particle size, volume fraction, and the cryorolling procedure affect the microstructure, wear, and mechanical properties. This approach could broaden the uses of hybrid manufacturing by demonstrating its practical advantages and efficiency. Furthermore, this review highlights the importance of implementing machine learning (ML) models and life cycle assessment (LCA) in evaluating MMCs produced through stir casting. Full article

Antimony nanomaterials are becoming increasingly important in advanced functional applications, including catalysis, sensing, optoelectronics, and energy systems, motivating the development of reliable synthetic routes capable of producing high-purity Sb at the nanoscale. This study establishes a direct Zn-mediated reduction pathway for converting SbCl₃ into elemental Sb using acetone, ethanol, and methanol as reaction media. SbCl₃ was first dissolved in each solvent, followed by controlled addition of Zn powder under mild heating (60 °C), magnetic stirring, and ultrasonic agitation. Acetone proved the most effective medium, achieving ~94% of the theoretical Sb yield, while suppressing the formation of the SbOCl intermediate observed in alcoholic solvents. Structural and compositional analyses using XRD and SEM/EDS confirmed the formation of a pure phase, nanocrystalline Sb with mean crystallite sizes of ~25 nm in acetone, ~27 nm in ethanol, and ~21 nm in methanol. TGA/DTA measurements from room temperature up to 800 °C revealed oxidative conversion to off-white antimony oxide under O₂ atmosphere and the formation of molten Sb droplets under N₂ atmosphere, consistent with the expected thermal transitions of high-purity Sb. Overall, the findings demonstrate that Zn-driven reduction of SbCl₃ in high-purity organic media provides an efficient and scalable approach for producing Sb nano-powders with solvent-dependent yields and nanoscale structural characteristics. Full article

Lonicerae japonicae flos (LJF) is a natural product with medicinal, edible, and ornamental value which has been developed into LJF tea. At present, LJF tea can be processed using four main fixation methods: fixation by sun drying (SG), hot-air oven drying (HG), stir-frying drying (CZ), and steaming (ZZ). However, a comparative analysis of the effects of different fixation methods on the quality of LJF tea has not been reported. This study comprehensively investigated the effects of these fixation methods on the appearance color, volatile components, and non-volatile components of LJF tea samples. Our findings demonstrated that LJF tea in the SG group had the highest L value, causing a brighter appearance, which was mainly caused by the retention of organic acids and flavonoids. Additionally, LJF tea in the SG group had a higher content of aroma components than other groups. These results suggested that sun drying may be beneficial for improving the quality of LJF tea. This study provided a reference for the selection of fixation methods for LJF tea and offered a clue for quality improvement of LJF tea. Full article

The continuous increase in electronic power densities demands thermal management solutions that surpass the conventional heat sink designs. This study introduces a synergistic approach that combines constructal design principles with Friction Stir Processing (FSP) to create next-generation heat sinks featuring an optimized geometry and locally enhanced thermal conductivity. Constructal design provides a physics-based framework for routing heat through preferential paths, whereas FSP enables the fabrication of these paths by refining the microstructure and reducing defect density, thereby improving thermal transport properties. Experimental validation on the AA6082-T651 aluminum alloy demonstrated a 21% increase in thermal conductivity within the FSP-processed regions, as confirmed through electrical resistivity measurements and thermal step-response tests. Microstructural analysis revealed significant grain refinement (from ~150 μm to 3–5 μm), which correlated with enhanced heat diffusion rates. A constructal scale-based model was developed to establish the relationship between the conductivity ratio and optimal geometric configuration, showing that a higher local conductivity shifts the design toward denser thermal pathways. These findings substantiate the feasibility of integrating geometry optimization with property tailoring, paving the way for scalable, high-efficiency heat sinks for advanced cooling systems. Full article