Reaction Parameters Research Articles

Limited reactivity of pyroxene and plagioclase in batch experiments with supercritical CO2 in the presence of NaCl and NaHCO3 in the context of CO2 sequestration via carbonation.

One-step high-pressure and high-temperature direct aqueous mineral carbonation of tailings derived from mining of Platinum Group Metals in South Africa requires a fundamental understanding of the reactivity of the most dominant mineral phases, i.e. pyroxene and plagioclase (66 wt. % and 12 wt. % of the bulk rock respectively) that are typically found in these tailings. The silicate minerals pyroxene and plagioclase were sampled from a pyroxenite footwall mined with the ore-bearing UG2 and from the Merensky Reefs outcropping in the eastern limb of the Bushveld Complex. These pyroxene and plagioclase grains were concentrated by gravity separation from the orthopyroxenite bulk rock and batch-reacted in a sodium chloride (NaCl) brine saturated with pure carbon dioxide (CO2) gas-only or seeded with sodium bicarbonate (NaHCO3; as an additional CO2 source) for 13days at 100°C and 10MPa. Pyroxene dissolved slightly but no weathering features were observed in plagioclase. Analyses of the filtrates obtained from the pyroxene sample in the absence of NaHCO3 showed an increased concentration of magnesium and calcium ions in the solution. However, they had also reached a cation saturation sealing. On the other hand, liquid samples from reactions where both CO2 gas and NaHCO3 were added to the solution exhibited a pronounced decrease in dissolved magnesium and calcium ions. XRD patterns of some of the post-reaction solids collected from the cation-depleted solution aliquots showed peaks of newly formed secondary magnesite and vermiculite. Moreover, the presence of magnesite was further confirmed by Raman shift analysis of the dried solid products. The formation of secondary magnesite was observed only in the experiments seeded with NaHCO3, specifically where the pre-reaction solid was pyroxene rich. Some of the resultant fluid chemistry was corroborated by the geochemical model that simulated the reaction parameters using the Geochemist Work Bench (GWB) software. Overall, the results indicate low pyroxene dissolution, which leads to limited carbonation. These findings suggest that the carbonation of PGM tailings may be constrained under the evaluated physicochemical conditions.

Reactions of Tertiary Aliphatic Cations with Silylated Alkynes: Substitution, Cyclization and Unexpected C-H Activation Products.

Capozzi's groundbreaking work in 1982 introduced a fascinating reaction involving highly reactive tertiary aliphatic cations and silylated alkynes. This reaction provided an innovative solution to the challenge of coupling a fully substituted tertiary aliphatic fragment with an alkyne moiety. Building upon Capozzi's pioneering efforts, we started an extensive exploration of reaction conditions to expand the initial scope of this reaction. Through meticulous control of the reaction parameters, we uncovered conditions capable of accommodating various functional groups, thereby enhancing the reaction's applicability. Intriguingly, our study revealed remarkable high diastereoselectivities for substrates with substitution in the a‑position. Additionally, we made an unexpected discovery: an intriguing C-H activation of a cyclooctane ring furnishing a cyclooctane-fused cyclobutene. These findings not only extend the utility of Capozzi's original concept but also underscore the potential of highly reactive cations in modern organic C-H activation reactions.

Upcycling of Organic and Inorganic Waste into MIL-88B(Fe) at Room Temperature for Tetracycline Degradation.

Upcycling organic and inorganic waste into value-added metal-organic frameworks (MOFs) presents a sustainable strategy for mitigating waste pollution and promoting economic viability. However, rapid synthesis of MOF materials derived from actual industrial waste under mild conditions remains challenging. Herein, Fe-MOF MIL-88B(Fe) was successfully fabricated within 1 h at room temperature using galvanizing pickling waste liquid and terephthalic acid derived from waste poly(ethylene terephthalate). The resulting Fe-MOF (s-MIL-88B(Fe)) was employed to activate peroxymonosulfate (PMS) under UV light irradiation, achieving over 87% degradation of tetracycline hydrochloride (TCH) within 15 min. The effects of the reaction parameters on TCH degradation were thoroughly investigated. s-MIL-88B(Fe) demonstrated good stability and reusability, maintaining 96% of the initial activity after five cycles. The system also demonstrated adaptability to various organic pollutants and water matrices. Radicals (SO4-•) and nonradicals (1O2, h+) identified as the key reactive species promoted TCH degradation. The formation mechanism of reactive species and the degradation pathway of TCH are proposed. Toxicity evaluation verified the reduced toxicity after the degradation. This work provides a sustainable approach to upcycling industrial waste into MOF-based materials for efficient environmental remediation under mild conditions.

Removal of Malachite Green Dye from Aqueous Solution by a Novel Activated Carbon Prepared from Baobab Seeds Using Chemical Activation Method.

Two activated carbons were synthesized from baobab seeds (BSs) using two activators, sulfuric acid (BS-AAC) and sodium hydroxide (BS-BAC), for dye removal from aqueous solutions. Malachite green (MG) was used as a model dye. SEM, FTIR, TGA, and surface area were used to characterize the feedstock and synthesis activated carbons. According to the SEM results, the surface morphology differed significantly from that of the raw material due to the many pores created by activating agents during carbonization. Various surface groups existed on the activated carbon surface as shown by FTIR analysis. An oxidation process utilizing hydrogen peroxide (H2O2) was investigated for MG. Various reaction parameters such as pH value, H2O2 concentration, and activated carbon dosage were investigated for the oxidative degradation of MG. By using BS-AAC and BS-BAC, 97.9% and 78% dye degradation efficiency in aqueous solutions, respectively, was achieved under optimal conditions. This study reveals that MG dye degradation increases with solution pH, making BS-AAC and BS-BAC ineffective at low pH values. However, degradation declines above pH 6. Based on the BS-AAC data, MG removal kinetics were fitted with a first-order kinetic model, while BS-BAC data were fitted with a second-order kinetic model. It was demonstrated that activating baobab with sulfuric acid can form a novel activated carbon that can quickly remove MG from aqueous solutions. The results showed that the removal of malachite green was over 89% for AC-AAC and 77% for AC-BAC, even after four regeneration cycles.

Emulsion Polymerization of Styrene to Polystyrene Nanoparticles with Self-Emulsifying Nanodroplets as Nucleus.

The mechanism of the emulsion polymerization of styrene to polystyrene nanoparticles (PSNPs) remains a subject of debate. Herein, a series of reaction parameters with different surfactant concentrations, monomer contents, temperatures, and equilibration times were investigated to understand the formation mechanism of PSNPs, which demonstrate a correlation between the properties of PSNPs and the mesostructure of the premix. Cooling the model systems with self-emulsifying nanodroplets (SENDs) in the early reaction stages resulted in the hollow polystyrene spheres (H-PSSs), ruptured PSNPs, and dandelion-like PSNPs, further indicating that the oil nanodroplets are the key sites for the formation of PSNPs. Therefore, the oligomer radicals generated in the medium at the early polymerization stages are preferentially captured by the oil-H2O interface, and once in the oil droplets, the oligomeric radical continues to grow until colliding with another radical or monomers run out. The self-emulsifying oil nanodroplets with a particle size of 100-300 nm are formed under high temperature and low surfactant concentration conditions and serve as nucleation sites. This study not only contributes to a profound understanding of the correlation between the mesostructure and nucleation pathways but also paves the way for the flexible regulation of the monodispersity and morphology of PSNPs.

Biobased Strategies for E-Waste Metal Recovery: A Critical Overview of Recent Advances

The increasing e-waste volumes represent a great challenge in the current waste management landscape, primarily due to the massive production and turnover of electronic devices and the complexity of their components and constituents. Traditional strategies for e-waste treatment focus on metal recovery through costly, energetically intensive, and environmentally hazardous processes, such as pyrometallurgical and hydrometallurgical approaches, often neglecting other e-waste constituents. As efforts are directed towards creating a more sustainable and circular economic model, biobased alternative approaches to these traditional techniques have been increasingly investigated. This critical review focuses on recent advances towards sustainable e-waste treatment, exclusively considering studies using e-waste sources. It addresses, from a critical perspective, approaches using inactive biomass, live biomass, and biogenic compounds, showcasing the diversity of strategies and discussing reaction parameters, advantages and disadvantages, challenges, and potential for valorization of generated by-products. While ongoing research focuses on optimizing operational times and metal recovery efficiencies, bioprocessing approaches still offer significant potential for metal recovery from e-waste. These approaches include lower environmental impact by reducing energy consumption and effluent treatments and the ability to recover metals from complex e-waste streams, paving the way for a more circular economy in the electronics industry.

Structural Transformation and Degradation of Cu Oxide Nanocatalysts during Electrochemical CO2 Reduction.

The electrochemical CO2 reduction reaction (CO2RR) holds enormous potential as a carbon-neutral route to the sustainable production of fuels and platform chemicals. The durability for long-term operation is currently inadequate for commercialization, however, and the underlying deactivation process remains elusive. A fundamental understanding of the degradation mechanism of electrocatalysts, which can dictate the overall device performance, is needed. In this work, we report the structural dynamics and degradation pathway of Cu oxide nanoparticles (CuOx NPs) during the CO2RR by using in situ small-angle X-ray scattering (SAXS) and X-ray absorption spectroscopy (XAS). The in situ SAXS reveals a reduction in the size of NPs when subjected to a potential at which no reaction products are detected. At potentials where the CO2RR starts to occur, CuOx NPs are agglomerated through a particle migration and coalescence process in the early stage of the reaction, followed by Ostwald ripening (OR) as the dominant degradation mechanism for the remainder of the reaction. As the applied potential becomes more negative, the OR process becomes more dominant, and for the most negative applied potential, OR dominates for the entire reaction time. The morphological changes are linked to a gradual decrease in the formation rate for multicarbon products (C2H4 and ethanol). Other reaction parameters, including reaction intermediates and local high pH, induce changes in the agglomeration process and final morphology of the CuOx NPs electrode, supported by post-mortem ex situ microscopic analysis. The in situ XAS analysis suggests that the CuOx NPs reduced into the metallic state before the structural transformation was observed. The introduction of high surface area carbon supports with ionomer coating mitigates the degree of structural transformation and detachment of the CuOx NPs electrode. These findings show the dynamic nature of Cu nanocatalysts during the CO2RR and can serve as a rational guideline toward a stable catalyst system under electrochemical conditions.

Process optimization and kinetics of biodiesel production from microalgal oil using potassium doped biochar heterogeneous catalyst

Biodiesel is considered to be an economical and eco-friendly substitute to fossil fuels. The present research was focused on the synthesis of potassium doped biochar catalyst from wood dust waste. The synthesized activated biochar catalyst was subjected to characterization using various techniques such as FT-IR, SEM-EDAX, XRD analysis which showed possible higher catalytic efficiency. The microalgae Chlorella vulgaris oil was used for the biodiesel production through transesterification reaction using the synthesized potassium doped biochar catalyst. The reaction parameters were optimized using statistical methods and the optimized conditions were found to be of 5.46% of catalyst dosage, 10.39:1 of methanol to algal oil ratio, 61.41 °C of temperature and 75.3 min of time with the highest biodiesel yield of 91.9%. The reaction kinetics was studied and it was found to follow the first-order kinetics with an activation energy of 12.18 KJ/mol. The catalyst reusability study exhibited higher catalytic performance until fourth cycle. Overall, the utilization of microalgae as a biofuel source and industrial waste as a catalyst contributes to sustainable biodiesel production and promotes a greener environment by reducing dependency on fossil fuels and minimizing industrial waste.

Photokinetics of Photothermal Reactions.

Photothermal reactions, involving both photochemical and thermal reaction steps, are the most abundant sequences in photochemistry. The derivation of their rate laws is standardized, but the integration of these rate laws has not yet been achieved. Indeed, the field still lacks integrated rate laws for the description of these reactions' behavior and/or identification of their reaction order. This made difficult a comprehensive account of the photokinetics of photothermal reactions, which created a gap in knowledge. This gap is addressed in the present paper by introducing an unprecedented general model equation capable of mapping out the kinetic traces of such reactions when exposed to light or in the dark. The integrated rate law model equation also applies when the reactive medium is exposed to either monochromatic or polychromatic light irradiation. The validity of the model equation was established against simulated data obtained by a fourth-order Runge-Kutta method. It was then used to describe and quantify several situations of photothermal reactions, such as the effects of initial concentration, spectator molecules, and incident radiation intensity, and the impact of the latter on the photonic yield. The model equation facilitated a general elucidation method to determine the intrinsic reaction parameters (quantum yields and absorptivities of the reactive species) for any photothermal mechanism whose number of species is known. This paper contributes to rationalizing photokinetics along the same general guidelines adopted in chemical kinetics.

Effect of Amino Acids on the Synthesis of NiFe2O4/Au Hybrid Nanoparticles

Hybrid nanoparticles, composed of magnetic oxides and gold, have garnered significant interest due to their potential applications in various fields, including catalysis, diagnostics, and nanomedicine. In this study, the effect of reaction parameters on the reduction of HAuCl4 by different non-sulfur amino acids (glycine, L-serine, L-tryptophan, and L-tyrosine) was determined using the design of experiment (DOE) method. The results of the analysis of the regression equations were used to select the conditions and develop a methodology for the preparation of the hybrid magnetic NiFe2O4/Au nanoparticles (NPs) by direct reduction of gold on the magnetic surface using the aforementioned amino acids as the reducing and stabilizing agents simultaneously. The materials were characterized using XRD, TEM, XPS, and Vis/FTIR spectroscopy. The results indicate the successful synthesis of magnetic NiFe2O4/Au nanoparticles with all amino acids used, but the size of the gold crystals, their surface density, and the details of the NP structure (inlaid or a core–shell structure) depend on the amino acid used. The mechanism of the gold deposition on the magnetic core surface and the difference in the effect of various amino acids are discussed. The developed synthesis strategy can be extended to other metal ferrites and iron oxides.

A Structural Bioinformatics-Guided Study of Adenosine Triphosphate-Binding Cassette (ABC) Transporters and Their Substrates.

Adenosine triphosphate-binding cassette (ABC) transporters form a ubiquitous superfamily of integral membrane proteins involved in the translocation of substrates across membranes. Human ABC transporters are closely linked to the pathogenesis of diseases such as cancer, metabolic diseases, and Alzheimer's disease. In this study, four ABC transporters were chosen based on (I) their importance in humans and (II) their score in a structural bioinformatics screen aimed at the prediction of crystallisation propensity. The top-scoring ABC transporters' orthologs (Mus musculus-mouse ABCB5, Ailuropoda melanoleuca-giant panda ABCB6, Myotis lucifugus-little brown bat ABCG1 and Mus musculus ABCG4) were then expressed in Saccharomyces cerevisiae with a combined green fluorescent protein and polyhistidine tag, enabling visualisation and purification. After partial purification and in the presence of the detergent (n-dodecyl-β-D-maltoside), the kinetic parameters of the ATP hydrolysis reactions of the orthologs were determined, as well as the extent of stimulation of their activity when presented with putative substrates. We discuss the efficiency of such bioinformatics approaches and make suggestions for their improvement and wider application in membrane protein-structure determination.

Evaluating the Potential of Microdroplet Flow in Two-Phase Biocatalysis: A Systematic Study.

Two-phase biocatalysis in batch reactions often suffers from inefficient mass transfer, inconsistent reaction conditions, and enzyme inactivation issues. Microfluidics offer uniform and controlled environments ensuring better reproducibility and enable efficient, parallel processing of many small-scale reactions, making biocatalysis more scalable. In particular, the use of microfluidic droplets can increase the interfacial area between the two phases and can therefore also increase reaction rates. For these reasons, slug flow has been extensively used in two-phase biocatalysis in recent years. However, microdroplet flow has been largely neglected for this application despite its great potential. In this work, we performed biphasic biocatalysis in microfluidic droplets, both in microdroplets and slugs, as well as in batch, and systematically investigated the effect of various reaction parameters on the outcome of the reaction. We show that microdroplet flow outperforms the more commonly used batch and slug flow configurations for most reaction conditions by providing shorter substrate diffusion paths and larger interfacial area for the reaction. The potential trade-off between maximized mass transfer and possibly higher enzyme inactivation rates in small droplets with large surface-to-volume ratios was also investigated for the first time, and a pipeline was established to allow evaluation in other reactions. Finally, the effect of surfactant necessary for microdroplet stabilization was also investigated in all reaction setups for the first time, and it was shown that a properly selected surfactant can have a positive effect at low concentrations by creating more stable emulsions and smaller droplets, thus increasing the interfacial area between the two phases.

Reactive Brownian Dynamics of Chemically Fueled Droplets: Roles of Attraction and Deactivation Modes.

The self-assembly of biological membraneless organelles can be mimicked by active droplets resulting from chemically fueled microphase separation. However, how the nonequilibrium, transient structure of these active droplets can be controlled through the physicochemical input parameters is not yet well understood. In our work, a chemically fueled two-state chemical reaction and subsequent droplet growth and decay are modeled with a reactive Brownian dynamics simulation in two spatial dimensions. In our model, particles that are activated via the consumption of fuel become attractive and can accumulate into droplets. A local-density-dependent distinction of the droplet's 'internal' and 'external' particles allows for structural feedback by giving further control over the deactivation process. The simulation shows that the deactivation of only external particles slows down the decay and stabilizes the droplets, whereas the deactivation of only internal particles can lead to a temporary encapsulation of deactivated particles (in nonequilibrium 'core-shell' structures) where the chemically active particles serve as an outer shell. Additionally, the role of hydrophobicity resembled by the attraction energy ε and the dependency of the nonequilibrium droplet formation on the various parameters of the chemical reaction are investigated. For example, a high attraction energy can lead to transient finite-size crystalline droplets, while other parameter choices indicate bimodal droplet size distributions at specific times. Similarities and differences to related experiments are discussed.

Utilization of borax production waste in zinc (Zn+2) adsorption from industrial wastewater

Borax production waste materials were determined as a possible adsorbent to eliminate the zinc (Zn+2) concentration in industrial wastewater. To investigate the adsorption mechanism, reaction parameters were optimized such as solution pH, dilution ratio (initial concentration) and contact time. The effect of pH had a vital role on the adsorption efficiency. The optimum solution pH was selected as 9 and contact time was selected as 90 mins. In the isothermal and kinetic modeling, Temkin isotherm (R2: 0.9851) and Lagergren pseudo-second-order kinetic method (R2: 0.9999 − 9.9945) were determined as the best fitted functions. The results indicated the weak interaction between molecules of adsorbent and adsorbate that related to the physical adsorption. Rate constants of k2 were found between −16.5017 and 48.7805 whereas the values of qe were estimated in the range of 49.5050 and 96.1538 for the different dilution ratios. The results also proved that industrial wastes can be an option for water treatment processes.

Photoinduced Regiodivergent and Enantioselective Cross-Coupling of Glycine Derivatives with Hydrocarbon Feedstocks.

Regiodivergent asymmetric synthesis represents a transformative strategy for the efficient generation of structurally diverse chiral products from a single set of starting materials, significantly enriching their enantiomeric composition. However, the design of radical-mediated regiodivergent and enantioselective reactions that can accommodate a wide range of functional groups and substrates has posed significant challenges. The obstacles primarily lie in switching the regioselectivity and achieving high enantiodiscrimination, especially when dealing with high-energy intermediates. To address these issues, we have developed a new catalytic system that integrates photoinduced hydrogen atom transfer (HAT) and chiral copper catalysis, involving the fine-tuning of chiral ligands, additives, and other reaction parameters. The strategy facilitates regiodivergent and enantioselective cross-couplings between N-aryl glycine ester/amide derivatives and abundant hydrocarbon feedstocks through strong C(sp3)-H bond activation. This approach allows for the controlled and stereoselective formation of C(sp3)-C(sp3) and C(sp3)-N bonds, yielding a rich variety of C- or N-alkylated glycine esters and amides with commendable yields (up to 92% yield), exclusive regioselectivities (typically >20:1 rr), and high enantioselectivities (up to 96% ee). Our methodology not only provides a promising avenue for the stereoselective incorporation of alkyl functionalities onto specific sites of biologically significant molecules but also offers a practical approach for regioselectivity switching while simultaneously achieving high asymmetric induction within photochemical reactions.

Enhancing efficiency and control in DNA hydrogel synthesis: A dual rolling circle amplification approach and parameter optimization study.

DNA hydrogels are a focus of current research in the realm of cutting-edge functional biomaterials. Rolling circle amplification (RCA) technology has surfaced as a flexible approach for producing functional DNA hydrogels in a one-pot manner, owing to its effectiveness and ease of use. This study introduces a simple dual RCA approach for producing DNA hydrogels. Our research delves into the impacts of different reaction parameters, such as reaction buffer, ethylenediaminetetraacetic acid (EDTA) concentration, base pair types and ratios, circular DNA template concentration, and RCA temperature, on the yield, morphology, and rheological characteristics of the resulting DNA hydrogels. Our findings demonstrate that DNA hydrogels prepared with TE buffer containing 1mM EDTA, higher concentrations of circular DNA templates, and an RCA reaction temperature of 30°C exhibited improved morphological characteristics and favorable mechanical properties. Furthermore, while G-C base pairs significantly enhance the mechanical properties of the hydrogel at lower concentrations, their excessive presence may negatively impact both the formation and mechanical integrity of the hydrogel. The findings from this study are crucial for boosting the efficiency and cost-effectiveness of DNA hydrogel synthesis, enhancing their quality, and broadening their range of applications.

Development of Biosorbent from Orange Peel and Fish Skin Waste for usage in Petroleum Industry

In the present work biowaste orange peels and fish collagen-derived hydrophilic super-absorbent was synthesized using polyvinyl alcohol and methacrylic acid, and a hybrid natural pectin-collagen backbone. After optimization of different reaction parameters w.r.t. percentage grafting, the equilibrium water removal capacity of the smart polymer in three different petroleum fraction-water emulsions: petrol-water, diesel-water, and petroleum ether-water was studied and optimized to get the maximum water absorption. The higher equilibrium water uptake capacity was found in the petrol-water emulsion (1.6740 g/g) followed by diesel-water (1.5126 g/g) and petroleum ether-water emulsions (1.3537 g/g). All petroleum fraction-water emulsions, including petrol-water (n = 0.3566), diesel-water (n = 0.3375), and petroleum ether-water (n = 0.3678), were able to allow water to penetrate the 3-D network of the smart polymer through a Fickian diffusion mechanism. The pseudo swelling kinetic model showed that the experimental results were consistent order with theoretical equilibrium water uptake values: 1.9548 g/g (petrol-water), 1.7393 g/g (diesel-water) and 1.6149 g/g (petroleum ether-water) along with swelling rate constant ks = 8.234 ×10−3 g/g min (diesel-water), ks = 7.52 ×10−3 g/g min(petrol-water) and ks = 6.64 ×10−3 g/g min(petroleum ether-water). Further the candidate polymer exhibited the salt resistant water uptake behaviour w.r.t. 1.0, 5.0, 10.0 and 15.0% NaCl concentration and thus, such materials are of great importance in membrane technology. The findings demonstrated that biowaste superabsorbent has a great potential as an environment friendly, cost-effective and “waste to wealth” for removing water from various petroleum fractions in petroleum industries.

Influence of preparation method on ZnO/Al2O3 composite: Physicochemical attributes and catalytic performance toward transesterification of waste cooking oil

Utilization of low-grade feedstocks, such as non-edible and waste oils, is considered one of the possible ways to achieve sustainability in biodiesel production and in this respect, zinc oxide (ZnO) is found to have significant important as a heterogeneous catalyst for biodiesel synthesis from high free fatty acid (FFA) oil due to its high activity, amphoteric property and nontoxicity. Meanwhile, there is a dearth of information on the impact of preparation method on catalytic activity of supported ZnO catalyst. Herein, physicochemical attributes of alumina supported zinc oxide (ZnO/Al2O3) catalysts prepared by three different techniques (coprecipitation, hydrothermal and impregnation) were examined, and catalytic activities of the composites in transesterification of high FFA waste cooking oil (WCO) were investigated. The findings revealed a clear influence of preparation method on properties of the composite catalysts, including textural, thermal stability, crystallographic structure, active sites density, morphological-elemental composition, and molecular structure and crystallinity. As a result, ZnO/Al2O3 composites exhibited different performances toward conversion of high FFA oil to fatty acid methyl esters (FAME) via transesterification process. The combined influence of catalyst type and reaction parameters on FAME content was studied using Taguchi optimization approach. FAME contents of 95.2, 89.1 and 84.7 % were respectively offered by ZnO/Al2O3 composites prepared by impregnation, hydrothermal and coprecipitation methods at 65 °C for 4 h with 12:1 methanol/WCO molar ratio and 3.0 wt% catalyst dosage. The obtained findings suggested that surface and textural properties, rather than morphological and structural features, were the significant factors in determining performance of the composite catalysts.

Thermal performance of DispersedInorganic magnetic hybrid nanomaterials into mixed convective flow through flexible porous disks

AbstractThis study applies advanced AI techniques, including machine learning algorithms, to explore the numerically unsteady laminar flow of viscous and incompressible fluids in coaxially swirled porous disks, with applications in engineering sciences. Our focus encompasses the effects of magnetic hybrid nanomaterials and the dynamic behaviors associated with expanding/contracting and injection/suction. Utilizing single‐phase simulations, we address nonlinear coupled ordinary differential equations set against appropriate boundary conditions. Key parameters of our study include permeability and relaxation, as well as the influence of chemical reactions and mixed convection on fluid behaviors. The thermophysical properties of Al2O3/Cu nanoparticles have been by varying their morphological aspects. For the hybrid nanofluids flow, the aggregation of nanoparticle volume fraction has been designed critically in conjunction with an energy and mass transfer equation. Because dimensionless ordinary differential equations are employed, the obtained expression is transmuted using the obliging transformation technique. The desired nonlinear system of ODEs is implemented using an accurate numerical method. Our findings reveal significant impacts of chemical reaction parameters on the Sherwood number and a marked increase in the skin friction coefficient, Nusselt number, and Sherwood number as nanoparticle volume fraction rises from 2% to 7%.

Diastereodivergence in catalytic asymmetric conjugate addition of carbon nucleophiles.

Catalytic asymmetric conjugate additions of carbon nucleophiles have emerged as a potent tool for constructing multi-stereogenic molecules with precise stereochemical control. This review explores the concept of diastereodivergence in such reactions, focusing on strategies to achieve selective access to diverse diastereomeric products upon carbon-carbon bond formation. Drawing from a rich array of examples, we delve into key approaches for controlling the stereochemical outcome of these transformations, including alteration of alkene geometry, fine-tuning of reaction parameters, synergistic catalysis, and isomerization of conjugate adducts. Additionally, we highlight the iterative strategies for conjugate additions, showcasing their potential for diastereodivergent synthesis of methyl-branched stereocenters in 1,3-relationships. By presenting a concentrated overview of this significant topic, this review aims to provide valuable insights into the design and execution of stereodivergent catalytic conjugate additions, offering new avenues for advancing stereoselective synthesis and structural diversity in organic synthesis.