Search Results (64)

The rapid growth in the electric vehicle sector has increased demand for advanced battery thermal management systems (BTMSs) with high heat-dissipation capacity and temperature uniformity. Immersion cooling using dielectric fluids has recently been recognized as a promising alternative technology to conventional indirect liquid cooling methods. This study investigates the thermal and hydrodynamic behaviour of a sixteen-lithium-ion cell battery (LIB) module immersed in low-viscosity dielectric fluids using three-dimensional computational fluid dynamics simulations. In this context, a total of twenty dielectric fluids are evaluated using the ANSYS Fluent solver, with particular emphasis on the effects of key thermophysical properties, including viscosity, density, specific heat capacity, and thermal conductivity. The simulation findings reveal that mineral oil and PAO4 yield the lowest maximum LIB cell temperatures, with a reduction of approximately 4 K compared to the least effective dielectric fluids, such as undecane and cumene. Moreover, in terms of temperature uniformity, mineral oil, Novec 7000, and PAO4 exhibit the most homogeneous temperature distributions among the twenty dielectric fluids. In addition, they show an improvement in the temperature uniformity index of approximately 32.4% compared with the least effective dielectric fluid, cumene. On the other hand, mineral oil and PAO4 generate significantly higher pressure drops because of their relatively high viscosities, which increases hydraulic resistance and pumping power requirements. These findings demonstrate that excellent thermal performance does not necessarily correspond to optimal overall thermo-hydraulic behaviour. Overall, the results confirm that immersion-BTMS performance is governed by a complex interaction between dielectric fluid thermophysical properties and flow behaviour, highlighting the importance of coupled thermo-hydraulic optimization in the selection of dielectric fluids for next-generation immersion-cooled battery systems. Full article

This study develops a quantitative kinetic framework for graft copolymerization of methyl methacrylate (MMA) and styrene (ST) onto natural rubber latex (NRL), with emphasis on Redox initiation and Interfacial polymerization in a multiphase system. Experiments were conducted using a cumene hydroperoxide/tetraethylenepentamine (CHPO/TEPA) system. Core–shell particles, consisting of a soft NR core and a rigid poly(vinyl monomer) shell, were obtained at 40–60 °C with initiator concentrations of 0.0051–0.0205 mol L⁻¹ and monomer concentrations of 0.39–0.83 mol L⁻¹. Radical generation occurs predominantly at the aqueous rubber interface, where monomer partitioning takes place between phases. This leads to simultaneous homopolymerization in the aqueous phase, while grafting occurs on the rubber backbone. Overall conversion (x_p), graft conversion (x_g), and grafting efficiency were determined gravimetrically, while morphology was confirmed by FTIR and TEM. The conversion profiles show nonlinear behavior consistent with power-law kinetics, allowing formulation of rate expressions for overall polymerization rate (R_p) and grafting rate (R_g). Reaction order and Arrhenius analyses indicate fractional, heterogeneous behavior characteristic of multiphase reaction kinetics. Styrene shows lower activation energy, whereas MMA exhibits higher collision frequency. The model reproduces experimental trends well (R² up to 0.95) and provides insight into propagation–grafting competition in natural rubber latex systems. Full article

This study focuses on simulating and optimizing cumene (isopropylbenzene) production via the alkylation of benzene with propylene using a beta zeolite catalyst. Two process configurations were evaluated: a conventional setup without a transalkylation reactor and an enhanced configuration incorporating a transalkylation unit to convert byproducts back into cumene. The process was modeled under steady-state conditions in Aspen HYSYS using plug flow reactors and the Peng–Robinson fluid package, with reaction kinetics derived from established literature on zeolite-catalyzed systems. Optimization studies examined the effects of reactor temperature, pressure, and the benzene-to-propylene molar ratio. Increasing the reactor temperature to 178 °C improved propylene conversion to 96.20%, while raising the pressure from 3540 kPa to 3600 kPa further enhanced it to 96.24%. By optimizing the benzene-to-propylene molar feed ratio to approximately 1.02:1 and increasing the fresh benzene feed to 138.5 kmol/h, cumene production reached 135.792 kmol/h while minimizing byproduct formation. Comparative analysis revealed that the configuration without a transalkylation reactor generated 4.171 kmol/h of diisopropylbenzene (DIPB) as waste, representing both economic loss and environmental concern due to its toxicity. In contrast, the integration of a transalkylation reactor enabled the conversion of DIPB into additional cumene, significantly improving process efficiency and sustainability. These findings demonstrate that optimizing reaction conditions and integrating a transalkylation step substantially enhances cumene yield and reduces waste, leading to a more viable and environmentally friendly industrial process. Full article

Organoselenium chemistry has undergone remarkable development over the past five decades, evolving from its initial association with high toxicity into a field with pivotal contributions to materials science, organic synthesis, catalysis, and Medicinal Chemistry. Among the diverse biological activities displayed by organoselenium compounds, their redox behaviour is particularly compelling, as many of these molecules act as efficient mimetics of the antioxidant enzyme glutathione peroxidase (GPx). In this work, we investigated the GPx-like activity of a series of N,N′-diaryl selenoureas toward the depletion of H₂O₂ and cumene hydroperoxide (CumOOH) as model ROS. Their reactivity was correlated with the electronic nature of the aryl substituents using a Hammett-type analysis, revealing a strong dependence of the reaction rate on remote electronic perturbations within the aromatic ring. Combined UV and NMR studies provided mechanistic evidence supporting a catalytic cycle in which selenoureas, operating at sub-stoichiometric loadings (1 mol%) and using a thiol as a cofactor-like molecule, can be used to efficiently scavenge ROS with half-lives of only a few minutes (~10–60 min). Furthermore, these selenoureas exhibited potent antiproliferative activity across several human solid tumour cell lines. Overall, these results offer mechanistic insight into the ROS-eliminating pathways of selenoureas and highlight their potential as chemopreventive or anticancer agents. Full article

The cleavage of cumene hydroperoxide (CHP) via the Hock rearrangement is a cornerstone process in the chemical industry, responsible for over 90% of global phenol and acetone production. Despite its industrial significance, the conventional use of homogeneous sulfuric acid catalysis presents critical drawbacks, including severe equipment corrosion, generation of hazardous waste, and the need for complex neutralization steps. This review explores the transition toward heterogeneous solid acid catalysts as a sustainable alternative, emphasizing the relationship between catalyst structure, surface acidity, and reaction performance. Key catalyst families—such as ion-exchange resins, zeolites, and heteropolyacids—are systematically evaluated, with a focus on how Brønsted acid site density and porous architecture influence catalytic activity and selectivity. Particular attention is given to deactivation mechanisms, including coking, leaching of active species, and poisoning by inorganic cations, alongside mitigation strategies enabled by rational catalyst design and regeneration protocols. Additionally, we highlight recent progress in reactor engineering, particularly the integration of solid acid catalysts in reactive distillation and microchannel configurations. These insights offer a strategic perspective for developing more efficient and environmentally benign industrial processes for the Hock cleavage of cumene hydroperoxide. Full article

With global plastic production creating immense environmental pressure and conventional recycling methods facing limitations, advanced chemical recycling techniques are crucial. This paper presents details of the design, construction, and operation of two fluidized reactors: a laboratory-scale (LS) reactor and a large-scale laboratory reactor (LSLR) for the catalytic pyrolysis of mixed plastic waste. A waste stream simulating municipal collection, consisting of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS), was processed using a custom Ni/γ-Al₂O₃ catalyst and an industrial G-0110 catalyst in a two-stage system. The large-scale reactor demonstrated high efficiency, achieving a 90% yield of valuable pyrolysis oil and waxes, a 2% yield of syngas, and an 8% yield of solid residue containing mainly carbon at operating temperatures between 400 and 453 °C. The resulting liquid and wax fractions contained a rich mixture of aliphatic and aromatic hydrocarbons (such as styrene, indene, benzoic acid, toluene, and cumene), confirming their potential as a feedstock for the chemical industry. These results establish that two-stage catalytic pyrolysis in a fluidized bed reactor is a highly effective and promising technology for upcycling mixed plastic waste into valuable resources. Full article

Aging underground pipeline infrastructure across the United States, including systems used for potable water supply, wastewater collection, and stormwater conveyance, has exceeded its intended service life, emphasizing the need for replacement or rehabilitation to maintain reliable service to communities. Among available trenchless technologies, cured-in-place pipe (CIPP) is widely applied because it minimizes surface disruption and is well-suited for use in densely populated areas. Despite these advantages, environmental concerns remain regarding the release of total volatile organic compounds (VOCs) during CIPP installation and curing. This study evaluates total VOC emissions from CIPP liners under field conditions. Air samples were collected at six installation sites across the United States before, during, and after installation and curing to quantify key VOC species. Multiple sampling methods were employed, including photoionization detectors (PIDs), Summa canisters, and personal worker sampling. The measured compounds included styrene, cumene, acetophenone, hexane, toluene, and ethanol. Measured concentrations were compared with occupational exposure limits established by the U.S. Environmental Protection Agency (USEPA), the National Institute for Occupational Safety and Health (NIOSH), and the Occupational Safety and Health Administration (OSHA). The results indicate that styrene was the dominant compound within active CIPP work zones, with peak concentrations reaching 25.5 ppm during curing. In contrast, VOC concentrations decreased substantially within five feet downwind of the work zone. Overall, the findings suggest that potential public exposure risks are limited, while workers directly involved in CIPP operations may experience elevated short-term exposures during installation and curing activities. Full article

Organic and inorganic peroxides can induce intracellular redox homeostasis. In this study, a γ-cyclodextrin/genistein inclusion complex (γ-CD/GEN) was constructed to systematically elucidate the molecular mechanism by which it catalyzes GPx4-mediated peroxide reduction. The results indicate that the incorporation of γ-CD effectively disrupts the aggregated state of GEN, achieving an encapsulation efficiency (EE) exceeding 40%. Surface-enhanced Raman spectroscopy (SERS) analysis reveals significant differences in the catalytic behavior of γ-CD/GEN toward cumene hydroperoxide (CHP) and hydrogen peroxide (H₂O₂): the reduction efficiency of CHP depends on both the concentration of γ-CD/GEN and GPx4, whereas the reduction of H₂O₂ is primarily regulated by the concentration of γ-CD/GEN. Isotope effect studies demonstrate that the reduction of CHP relies more on radical-initiated reactions, while the reduction of H₂O₂ involves proton transfer, with the differences in reduction rates correlating with their respective redox mechanisms. Molecular docking and molecular dynamics simulations further confirm that γ-CD/GEN can stably bind to the Sec (Cys)-46 site in the active center of GPx4, thereby enhancing its catalytic activity. This study provides a theoretical basis for the development of antioxidant strategies based on the precise regulation of enzyme activity. Full article

The antioxidant/prooxidant effects of dinitrosyl iron complexes (DNICs), physiological donors of nitric oxide (NO^•), are studied in reaction systems modeling processes with cytochrome c occurring in mitochondria under oxidative stress and leading to apoptosis. Using luminol-dependent chemiluminescence, DNICs with glutathione and phosphate ligands were shown to decrease the level of prooxidants in a reaction system containing ferricytochrome c and cumene hydroperoxide. Electron paramagnetic resonance (EPR) spectroscopy revealed that glutathione DNICs (DNICs-GS) intercepted the free radicals formed during the interaction between cytochrome c and tert-butyl hydroperoxide. DNICs-GS were also shown to prevent the formation of oligomeric forms of cytochrome c, which were induced by organic hydroperoxides. Reduced glutathione was less effective as an antioxidant than DNICs-GS or could even occasionally exhibit the prooxidant properties. Ferricytochrome c also catalyzed the formation of DNICs-GS with nitroxyl anion (NO⁻) taking part. Full article

Two-component dental materials are commonly used by the dentist for various applications (cementation of indirect restorations, filling of a cavity without layering, etc.). These materials are cured by redox polymerization. The (hydro)peroxide/thiourea/copper salt redox initiator system is well established and can be found in a wide range of commercially available dental materials. The thiourea is a key component of the initiator system. This study explores the influence of the nature of the thiourea reducing agent on the reactivity and efficiency of redox initiator systems. In this work, six different thiourea structures were investigated, in combination with copper(II) acetylacetonate and cumene hydroperoxide (CHP), to understand their impact on polymerization kinetics and mechanical properties of methacrylate-based materials. Various experimental techniques, including mass spectrometry (MS) and spectroscopic analyses, were employed to elucidate the underlying mechanisms governing these redox systems. The results highlight that thiourea plays a dual role, acting both as a reducing agent and as a ligand in copper complexes, affecting radical generation and polymerization efficiency. Structural modifications of thiourea significantly influence the initiation process, demonstrating that reactivity is governed by a combination of factors rather than a single property. Self-cure dental flowable composites exhibiting excellent flexural strength (>100 MPa) and modulus (>6000 MPa) were obtained using hexanoyl thiourea, N-benzoylthiourea, or 1-(pyridin-2-yl)thiourea as a reducing agent. The adjustment of the Cu(acac)₂ enables to properly set the working time in the range of 100 to 200 s. These findings provide valuable insights into the design of the next generation of redox initiating systems for mild and safe polymerization conditions. Full article

Background: Cyclophosphamide (CP) chemotherapy is commonly associated with various side effects. The development of an effective therapy capable of counteracting these effects is of great interest. Objectives: We evaluated the effects of a novel polyherbal formulation (PHF) on CP cytotoxicity in TM3 cells and fictive ejaculation in rats, and determined its possible mechanism. Methods: The phytochemical analysis of PHF was determined by GC-MS. Various oxidative stress-related parameters (DPPH, ABTS⁺, CUPRAC, FRAP, MMP, and DCF-DA) and the cytotoxicity (hemolysis and HET-CAM) of PHF were evaluated. Its effect on fictive ejaculation was tested by recording the electromyographic activities of bulbospongiosus muscles, and the involvement of TRPV1/TRPM2 channels was investigated using their specific agonists and antagonists. Results: We found that PHF contained various phytocompounds. PHF prevented CP-induced oxidative stress in TM3 cells, probably due to its strong antioxidant potential. For instance, PHF inhibited apoptosis, lipid peroxidation, and ROS generation. Furthermore, the activities of capsaicin (CAP) and cumene hydroperoxide (CHPx) were significantly lowered by PHF, indicating TRPV1 and TRPM2 inhibition. In the in vivo study conducted in spinal male rats, the number of contractions of the bulbospongiosus muscles was significantly (p < 0.001) lowered in the PHF + DOPA (1.54 ± 0.3) and PHF + CAP (2.43 ± 0.74) groups, compared with the DOPA (8.75 ± 0.71) and CAP (7.41 ± 1.01) groups, respectively. Additionally, PHF delayed the pro-ejaculatory effects of dopamine (by 17.6%) and capsaicin (by 32.69%). The in silico study revealed a strong binding affinity between the selected PHF phytocompounds and the active pockets of TRPV1 and TRPM2. HET-CAM and hemolysis assays revealed no harmful effects of PHF. Conclusions: PHF prevented CP cytotoxicity in TM3 cells and delayed the pro-ejaculatory effects of dopamine and capsaicin in spinal rats through dopamine and TRPV1 inhibition. PHF could be a potential candidate for the management of CP chemotherapy-related disorders, such as premature ejaculation, in particular. Full article

The combined effects of chitooligosaccharide–epigallocatechin gallate conjugate (CEC) at different concentrations (1, 2, and 3%, w/w) and cold atmospheric plasma (CAP) on the depurated Asian green mussel edible portion (AGM-EP) were investigated during refrigerated storage for 15 days. Among all the treatments, the microbial counts, total volatile bases (TMA-N and TVB-N), and lipid oxidation of AGM-EP-treated 3% CEC in conjunction with CAP (CEC-3-CAP) were lower than the other samples during 15-day storage (p < 0.05). Total viable bacteria (6.16 log CFU/g sample), psychrotrophic bacteria (3.24 log CFU/g sample), Vibrio spp. (2.47 log CFU/g sample), presumptive Pseudomonas (5.93 log CFU/g sample), and H₂S-producing bacteria (5.05 log CFU/g sample) counts of the CEC-3-CAP were lower than samples treated with 1 and 2% (w/w) CEC on day 15, as well as samples solely treated using CAP during refrigerated storage, irrespective of storage time. Additionally, CEC-3-CAP had significantly lower lipid oxidation (PV: 8.36 mg cumene hydroperoxide/kg sample and TBARS: 2.65 mg MDA/kg sample) as compared to those without CEC added and other samples (p < 0.05). The incorporation of CEC effectively mitigated lipid oxidation as supported by lower reduction of PUFAs in AGM-EP. Moreover, on day 0, no significant differences were observed in cooking loss or textural parameters (firmness and toughness) among the treatments (p > 0.05). However, as storage progressed, cooking loss increased in the CEC-3-CAP sample, while a noticeable decline in firmness and toughness was recorded (p < 0.05). This further attributed to the lower likeness attained for CAP-3-CAP on day 12, but the score was higher than the acceptable limit (5.0). Therefore, CAP together with CEC is a promising technology to prolong the shelf-life of depurated AGM-EP by at least 9 days as compared to the control (3 days), but it certainly needs further studies for the retention of textural properties and sensorial attributes. Full article

The influence of secondary porosity and the dimensionality of zeolitic structures with 1D and 3D pore systems on the accessibility of cumene to Brønsted acid sites was evaluated in this study. Zeolites Y, ZSM-5, and MOR, obtained through NH4F leaching and basic and acid treatments, were studied. Zeolites Y and ZSM-5 showed a significant increase in specific surface area while maintaining the micropore volume as well as an increase in the concentration of Brønsted acid sites following treatment. Zeolite MOR exhibited an increase in mesopore volume and retained Brønsted acidity. The impact of the treatments on catalytic properties was evaluated through cumene cracking, which yielded high catalytic conversion for the materials. This result is consistent with the goal of the model reaction to characterize Brønsted acid sites, enhance accessibility, and reduce diffusion paths. Full article

Steam reforming is an important industrial process for hydrogen production. Acetone, the by-product of phenol production from cumene peroxidation, is a useful source of hydrogen due to its availability and low value compared to hydrogen fuel. This study aimed to utilize the Gibbs free energy minimization method using the Soave–Redlich–Kwong (SRK) equation of state (EOS) to conduct a thermodynamic analysis of the steam reforming process for pure component acetone. The steam reforming process is temperature dependent, with increasing temperatures leading to higher hydrogen production. Competing reactions, particularly the exothermic reverse water–gas shift, impact hydrogen yields beyond 650 °C. The study identified 600 °C as the optimum temperature to strike a balance between maximizing hydrogen production and minimizing the reverse water–gas shift’s impact. The optimal hydrogen yield (70 mol%) was achieved at a steam-to-oil ratio (STOR) of 12. High STOR values shift the equilibrium of the water–gas shift reaction towards hydrogen production due to increased steam, effectively consuming acetone and favoring the desired product. Atmospheric pressure is optimum for hydrogen production because the equilibrium of gas phase reactions shifts in favor of the lighter components at lower pressures. Full article

Crude oil naphtha fraction C9 alkylbenzenes consist of trimethylbenzenes, ethyltoluenes, cumene, and n-propylbenzene. The major fraction of C9 alkylbenzenes is ethyltoluenes (ETs) consisting of three isomers: 2-ethyltoluene (2-ET), 3-ethyltoluene (3-ET), and 4-ethyltoluene (4-ET). Occupational and environmental exposure to ETs can occur via inhalation and ingestion and cause several health problems. Exposure to ETs causes eye and upper respiratory tract irritation, coughing, gagging, vomiting, griping, diarrhea, distress, and depressed respiration. Previous studies suggest that ETs target the respiratory tract and liver and produce several lesions in the nose, lungs, and liver areas. In the current study, we investigated the impact of low concentrations of ETs on cell metabolism, cell inflammation, steatosis, and fibrosis signaling in liver cell models in vitro. Dose-dependent exposure of 2-ET, 3-ET, and 4-ET to HepaRG and hepatocellular carcinoma (HCC) HepG2 and SK-Hep1 cells affects cell survival/real-time proliferation and increases ROS production. ETs induce inflammatory CAT, SOD1, CXCL8, IL1B, HMOX1, NAT1 (3), and STAT3 gene expression. Exposure of 2-ET, 3-ET, and 4-ET to HepaRG and HCC HepG2 and SK-Hep1 cells affects mitochondrial respiration/cellular energetics and upregulates metabolic CYP1-A1, CYP1-A2, CYP2-D6, CYP2-E1, CYP3-A4, CYP3-B4, and VEGFA gene expression. However, no significant change in lipogenesis-related gene expression and modulation of cell steatosis was observed after ET exposure. Acute exposure to induvial ETs and in combination or chronic 2-ET exposure alone modulates cell fibrosis markers such as AST, FGF-23, Cyt-7 p21, TGFβ, TIMP2, and MMP2 in liver cell models, suggesting that ETs target liver cells and may dysregulate liver function. Full article