Oxidative Cyclization Research Articles

Recovery and restoration of glass fibers from end‐of‐life composite waste through pyrolysis and partial oxidation processes combined with hot alkaline surface treatments

AbstractEnvironmental hazards caused by the ever‐increasing end‐of‐life (EoL) glass fiber reinforced polymer (GFRPs) composite waste is of major concern for the sustainable development of the industry. Compared to land filling or incineration, pyrolysis is one of the most promising environmentally friendly methods of disposal of EoL GFRPs. Pyrolysis not only results in recovery of clean glass fibers but other valuable products, such as oils. However, long processing time at elevated temperature leads to aggravation of already existed surface flaws along with the structural changes. Therefore, thermal conditioning of glass fibers results in severe deterioration of the strength in recovered fibers and hence limiting the use of recovered fibers to low end‐products. In this study, a new strategy was adopted where instead of complete cleaning of the fibers at pyrolysis stage, the fibers were partially oxidized and the complete removal of char from the surface of glass was done during hot alkaline etching. This strategy was opted to enhance the quality of the required fibers while reducing the processing time. The results showed ~200% increase in strength of fibers after the combined treatment of pyrolysis and post etching compared to the just pyrolyzed samples with etching time of just 1 min.Highlights End‐of‐life panels of GFRPs were pyrolyzed under inert environment of Argon. Residual char was partially removed through post oxidation under flowing air. Hot alkaline etching resulted in complete removal of char and surface defects. Partial oxidation and short etching cycles resulted in improved strength of recovered glass fibers.

High-temperature oxidation behavior of multi-phase ceramic particles-reinforced TiAl composites with different microstructures

The high-temperature oxidation behaviors of multiphase ceramic particle-reinforced TiAl composites with different microstructures were investigated. The TiAl composites were prepared via spark plasma sintering by introducing 0.5 wt % graphene oxide and 0.3 wt% SiC into Ti-48Al-2Nb-2Cr. The near-γ equiaxed microstructure, dual-phase microstructure, and nearly fully lamellar microstructure were obtained by sintering at 1200, 1250, and 1300 °C, respectively. Moreover, multiphase ceramic particles were uniformly distributed in the TiAl matrix. Cyclic oxidation was conducted at 950 °C in air for 100 h. The TiAl composite with the nearly fully lamellar microstructure exhibited the best oxidation resistance (mass gain of 1.83 mg/cm2) and that with the near-γ microstructure exhibited the worst oxidation resistance (2.47 mg/cm2). The superior oxidation resistance of the TiAl composite with the nearly fully lamellar microstructure is attributed to the uniform distributions of Ti2AlC particles at the α2/γ lamellae interfaces and Ti5Si3 particles at the lamellae colony boundaries, which hinder atomic diffusion. Moreover, the α2/γ lamellae colonies facilitate the formation of Nb-rich and Cr-rich phases at the interface of the oxide layer and substrate, which act as a protective barrier against atomic diffusion.

Flubendiamide provokes oxidative stress, inflammation, miRNAs alteration, and cell cycle deregulation in human prostate epithelial cells: The attenuation impact of synthesized nano-selenium using Trichodermaaureoviride

Flubendiamide (FBD) is a novel diamide insecticide extensively used with potential human health hazards. This research aimed to examine the effects of FBD on PrEC prostate epithelial cells, including Oxidative stress, pro-inflammatory responses, modifications in the expression of oncogenic and suppressor miRNAs and their target proteins, disruption of the cell cycle, and apoptosis. Additionally, the research investigated the potential alleviative effect of T-SeNPs, which are selenium nanoparticles biosynthesized by Trichoderma aureoviride, against the toxicity induced by FBD. Selenium nanoparticles were herein synthesized by Trichoderma aureoviride. The major capping metabolites in synthesized T-SeNPs were Isochiapin B and Quercetin 7,3′,4′-trimethyl ether. T-SeNPs showed a spherical shape and an average size between 57 and 96.6 nm. FBD exposure (12 μM) for 14 days induced oxidative stress and inflammatory responses via overexpression of NF-κB family members. It also distinctly caused upregulation of miR-221, miR-222, and E2F2, escorted by downregulation of miR-17, miR-20a, and P27kip1. FBD encouraged PrEC cells to halt at the G1/S checkpoint. Apoptotic cells were drastically increased in FBD-treated sets. Treatment of T-SeNPs simultaneously with FBD revealed its antioxidant, anti-inflammatory, and antitumor activities in counteracting FBD-induced toxicity. Our findings shed light on the potential FBD toxicity that may account for the neoplastic transformation of epithelial cells in the prostate and the mitigating activity of eco-friendly synthesized T-SeNPs.

Enhancing oxidation resistance via grain boundary engineering in L12-strengthened medium entropy alloys

The concept of grain boundary engineering (GBE) has been successfully applied to L12-strengthened (CoCrNi)94Al3Ti3 medium entropy alloy, with the aim of improving the oxidation resistance by increasing the ratio of special boundaries and suppressing discontinuous precipitation. Surprisingly, our results reveal that GBE treatment not only slows down the oxidation kinetics and but also alters the oxide scale from TiO2 and multi-defect Cr2O3 to continuous and protective Cr2O3 and Al2O3, thereby contributing to an enhanced oxidation and anti-spalling resistance. The GBE treatment reduces the oxidation weight gain of the current alloy from 1.950 mg cm–2 to 1.211 mg cm–2 after 100 h of cyclic oxidation at 800 °C. The findings show that the extensive outward diffusion of Ti accelerates ion transport and promotes microporosity, thus leading to more defects being formed in the oxide film. The GBE treatment suppresses the discontinuous precipitation of the Ti-bearing L12 phase and breaks the random large angular grain boundaries network, inhibiting the diffusion of Ti and ultimately enhancing the oxidation properties of the alloy. The current work provides an idea of oxidation resistance enhancement for Ti-bearing L12-strengthened alloys without changing the alloy composition.

Solvent-free oxidation of alcohols by a heterogeneous Fe3O4@SiO2-DTPA-Ru nanocatalyst

A novel magnetic heterogeneous ruthenium catalyst (Fe3O4@SiO2-DTPA-Ru) was prepared by using magnetic silicon spheres as support, ethylenediaminepentaacetic acid (DTPA) as functional ligands, ruthenium chloride as catalyst precursor. The results obtained after a series of characterizations showed that the catalyst Fe3O4@SiO2-DTPA-Ru was 5–15 nm in size with a 0.205 nm lattice and contained 0.31 mmol Ru/g catalyst. It also had a good thermal stability under 232°C which was verified by thermal filtration method. Besides, the saturation magnetic intensity was as high as 20.54 emu/g. The catalyst Fe3O4@SiO2-DTPA-Ru was applied for the first time into thirteen oxidation reactions of aromatic alcohols and showed good catalytic activity even the yields of eleven aromatic alcohols were all over 90%. In catalyzing 1-phenylethanol to acetophenone, its TOF and TON were 9677 h−1 and 6991, respectively. The Fe3O4@SiO2-DTPA-Ru catalyst could still maintain good reusability and catalytic performance after 15 cycles of 1-phenylethanol oxidation, which was superior to many reported catalysts and had great potential in future industrial production.

Oxidized-Sulfur Decorated Two-Dimensional Cobalt(II) Porphyrin Covalent Organic Framework as a Photocatalyst and Proof-on Action Study in Oxidative Cyclization of Thioamide

Oxidized-Sulfur Decorated Two-Dimensional Cobalt(II) Porphyrin Covalent Organic Framework as a Photocatalyst and Proof-on Action Study in Oxidative Cyclization of Thioamide

Preparation of magnetite nanoparticles and their application in the removal of methylene blue dye from wastewater

Wastewater is discharged in large amounts from different industries; thus, wastewater treatment is currently one of the main concerns, advanced oxidation is a promising technique for wastewater treatment. This research aims to synthesize magnetite nanoparticles and study their application in wastewater treatment via adsorption and advanced oxidation processes. Magnetite nanoparticles were synthesized via coprecipitation technique between ferric and ferrous sulfate at a molar ratio of 2:1. The prepared sample was characterized using FTIR, XRD, TEM, BET surface area, zeta potential, VSM, and UV‒visible spectroscopy. XRD confirmed the formation of a single face-centered cubic (FCC) spinel structure of Fe3O4. TEM revealed an average particle size of 29.2 nm and a BET surface area of 70.1 m2 g−1. UV‒visible spectroscopy revealed that the UV–visible peak of the sample was obtained at 410 nm. VSM confirmed the attraction of the sample to a magnet with a magnetization of 60 (emu/g). The removal efficiency of methylene blue was studied using adsorption and advanced oxidation methods. For adsorption, the studied parameters were dye concentration 2–10 ppm, 3–10 pH, and 50:300 mg Fe3O4/L. For advanced oxidation, peroxide was used with nanomagnetite as a catalyst, and the studied parameters were pH 2–11, magnetite dose 20–200 PPM, and peroxide dose 500–2000 PPM. The removal efficiency by adsorption reached 95.11% by adding 50 mg of Fe3O4/L and 10 ppm dye conc at 6.5 pH; on the other hand, in advanced oxidation, it reached 98.5% by adding 110 PPM magnetite and 2000 ppm H2O2 at pH 11. The magnetite nanoparticles were reused for ten cycles of advanced oxidation, for a 10% reduction in removal efficiency at the tenth cycle.

Long-term oxidation resistance of CrAl(Si)N coatings deposited on TiAl-based alloy at 950 °C

CrAl(Si)N coatings were deposited on Ti-48Al-2Cr-2Nb alloy by arc ion plating. Long-term cyclic oxidation behaviors of the CrAl(Si)N-coated alloy were investigated at 950 °C. The oxidation resistance of the Cr0.4Al0.5Si0.1N coating was significantly better than that of the Cr0.5Al0.5N coating. The addition of Si to the CrAlN coating promoted the formation of an almost continuous inner Al2O3 layer in the oxide scale. The continuous and dense Cr2O3/Al2O3 oxide layer acted as a diffusion barrier and retarded the inward diffusion of oxygen and outward diffusion of the coating elements. However, interdiffusion between the CrAl(Si)N coatings and the alloy was serious and a thick interdiffusion zone formed.

Developing advanced CrSi coatings for combatting surface degradation of N-type (Zr,Ti)Ni(Sn,Sb) and P-type (Zr,Ti)Co(Sn,Sb) half Heusler thermoelectric materials

In this study, advanced oxidation-protective CrSi coatings were developed and deposited on N-type (Zr,Ti)Ni(Sn,Sb) and P-type (Zr,Ti)Co(Sn,Sb) thermoelectric (TE) materials using an environmentally friendly closed field unbalanced magnetron sputtering PVD system. The oxidation behaviour of the CrSi-coated and uncoated samples was evaluated through static oxidation tests at 500 °C and 600 °C for 10h and 50 h, respectively. In addition, the samples were exposed to cyclic oxidation tests between 25 °C and 500 °C for 10, 30 and 50 cycles, with each cycle consisting of 1h of oxidation at 500 °C, to examine the coating ability to withstand thermal shock, which is involved in the service of TE devices. The surface morphology, cross-section layer structure, elemental distribution and phase constitution were analysed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and X-ray diffraction (XRD). The mass gain after the oxidation tests was measured and calculated for each sample to study the oxidation kinetics. The uncoated samples exhibited a considerable amount of oxidation, leading to change in the surface morphologies, and the formation of alternated layers including oxide products (Zr(Ti)O2, SnO2) and Ni3Sn4 compound for the N-type and (Zr(Ti)O2, SnO2, Sb2O4) and CoSb compound for the P-type material, after static and cyclic oxidation tests. The experimental work in this study has, for the first time, demonstrated that the CrSi coatings developed with very high thermal stability and oxidation resistance can effectively protect both the N-type and P-type materials from oxidation and sublimation even during cyclic oxidation tests. The strong affinity of Cr and Si to oxygen can trap oxygen, retard its inward diffusion and thus protect the TE material substrate from oxidation. This finding could pave the way towards the further development of long-life high-performance TE generators and devices, thus contributing to the net zero target.

Effect of cyclic oxidation temperature on compressive strength of Cu-based brake pad for high-speed train

The cyclic oxidation tests of Cu-based brake pads at temperatures of 25, 300, 400, 500, 550, 600, 650 and 700 °C were conducted to simulate the oxidation of the friction surface under different braking speeds. Furthermore, the effect of cyclic oxidation temperature on the compressive strength was investigated. The results show that the cyclic oxidation process of Cu-based brake pads can be divided into three stages: mild oxidation (≤400 °C), moderate oxidation (500–600 °C) and severe oxidation (≥650 °C). Mild oxidation results in the formation of spherical Cu2O particles. The surface is covered by Cu2O and Fe2O3 nanosheets for moderate oxidation. Severe oxidation is characterized by a continuous thick CuO film, Fe2O3 nanosheets, and eroded graphite particles. The compressive strength and toughness of Cu-based brake pads show a declining trend as the cyclic oxidation temperature rises. The compressive strength of the Cu-based brake pad after oxidized at 700 °C, recorded at 30.56 MPa, is considerably lower than that of the original samples, which was 132.2 MPa. This reduction in compressive strength is attributed to the embrittlement of the metallic matrix and the formation of pores from graphite oxidation.

Activation of peroxymonosulfate by β-FeOOH@Cia-MoS2 for enhancing degradation of tetracycline: Significant roles of surface functional groups and Fe/Mo redox reactions

Vertically oriented interstitial atom carbon-anchored molybdenum disulfide (Cia-MoS2) nanospheres loaded with iron oxyhydroxide (β-FeOOH) were proposed for modulating the surface catalytic activity and stability of the unsaturated catalytic system. The β-FeOOH@Cia-MoS2 efficiently activated peroxymonosulfate (PMS) to degrade 95.4% of tetracycline (TC) within 30 min, owing to the more sulfur vacancies, higher surface hydroxyl density, redox ability and electronic transmission rate of β-FeOOH@Cia-MoS2. According to the characterization and analysis data, the multiple active sites (Fe, Mo and S sites) and oxygen-containing functional groups (CO, –OH) of β-FeOOH@Cia-MoS2 could promote the activation of PMS to form reactive oxygen species (ROS). The oxidation cycle of Fe(II)/Fe(III) and Mo(IV)/Mo(VI), the electron transfer mediator of rich sulfur vacancies, as well as oxygen-containing functional groups on the surface of β-FeOOH@Cia-MoS2 synergistically promoted the formation of ROS (1O2, FeIVO, SO4•- and •OH), among which 1O2 was the main active oxidant. In particular, the β-FeOOH@Cia-MoS2/PMS system could still degrade pollutants efficiently and stably after five recycling cycles. Furthermore, this system had a strong anti-interference ability in the actual water body. This study provided a promising strategy for the removal of difficult-to-degrade organic pollutants.

Iodine Mediated Annulation of Triethylamine, Aldehydes and 2‐Aminopyridines for the Synthesis of 3‐Formyl‐Imidazo [1,2‐a]pyridine Derivatives

AbstractWith triethylamine as a synthon, an alternative method for the synthesis of 3‐formyl imidazo[1,2‐a]pyridines has been accomplished from aldehydes, and 2‐aminopyridines. The reaction proceeded via iodine‐catalyzed C−N bond cleavage of triethylamine, generation of α,β‐unsaturated aldehyde in situ, and oxidative cyclization with air as the oxygen source. This protocol may facilitate the synthesis of imidazo[1,2‐a]pyridine derivatives and provide a reference for the usage of triethylamine as a synthon.

Investigation of Cyclic Oxidation and Hot Corrosion Behaviour of Plasma-Sprayed NiCrAlY/Cr3C2/h-BN/Mo Coatings on T22 Boiler Steel Alloy

Investigation of Cyclic Oxidation and Hot Corrosion Behaviour of Plasma-Sprayed NiCrAlY/Cr3C2/h-BN/Mo Coatings on T22 Boiler Steel Alloy

Quantum Chemical Modeling of the Full Catalytic Cycle for Selective Oxidation of Propane to Propene on the M1 Phase of Mo–Te–Nb–O Mixed-Metal Oxide Catalysts

Quantum Chemical Modeling of the Full Catalytic Cycle for Selective Oxidation of Propane to Propene on the M1 Phase of Mo–Te–Nb–O Mixed-Metal Oxide Catalysts

Copper‐catalyzed oxidative intramolecular cyclization for the synthesis of 2‐hydroxy‐indolin‐3‐ones

The synthesis of substituted 2‐hydroxy‐indolin‐3‐ones has attracted considerable attention due to the frequent presence of the indole nucleus in numerous natural products and biologically active molecules. Herein, a direct access to 2‐hydroxy‐indolin‐3‐ones through copper‐catalyzed oxidative intramolecular cyclization of N‐(2‐acetylphenyl)picolinamide has been developed. This method exhibits good functional group tolerance, atom‐economy and avoids the pre‐functionalization of substrates.

The Rôle of Iron in Zeolite Beta for deNOx Catalysis

Selective catalytic reduction with ammonia (NH3-SCR) is a widely used deNOx process, employing zeolitic catalysts. Here, we examine framework substituted and extra-framework exchanged transition metal zeolite catalysts, in the extensively studied Fe – zeolite Beta focusing on the influence of the transition metal cation on the NH3-SCR reaction, and aiming to unravel the underlying mechanisms and their impact on catalytic performance. We use hybrid multiscale density functional theory (DFT)/molecular mechanics to investigate the NH3-SCR at various Fe-BEA active sites including systems with both framework and extra-framework Fe cations. The catalytically active sites under investigation include Fe-FeF-BEA, Fe-AlF-BEA, and Cu-FeF-BEA, (where the subscript F indicates framework species) on which the formation and consumption of key intermediates of both oxidation and reduction half cycles species are analysed. We show the distinctive ability of framework Fe sites to promote the formation of key nitrate and nitrosamine intermediates. Furthermore, we find a strong binding affinity of NH3 with framework Fe systems including Cu(II)-FeF-BEA, Fe(III)-FeF-BEA, and H-FeF-BEA compared to framework Al systems (Fe(III)-AlF-BEA). We explore the reduction potential of the framework Fe3+/Fe2+ in BEA zeolite and establish its feasibility in the presence of a Brønsted acid site. Our calculations clearly predict the bimetallic Cu-FeF system to be the best catalyst which supports a recent experimental report by Yue et al. (Chem. Eng. J. 2020, 398, 125515) for a related FeCu-SSZ-13 (CHA) zeolite. We provide a new understanding of the reactivity of Fe-BEA zeolites, suggesting the advantages of framework Fe over Al sites in NH3-SCR reactions, and establishing a foundation for interpretation of the rôle of framework cations in metal-exchanged zeolites.

(Invited) Semiconductor Facet Effects Toward Photocatalysis

Photo-induced charge transfer has been found to strongly depend on the exposed semiconductor surfaces. For instance, {110}-bound Cu2O rhombic dodecahedra exhibit a high photocatalytic activity toward dye degradation, but {100}-terminated Cu2O cubes are inert. Photocatalytic behaviors of Cu2O-based semiconductor heterostructures, such as Cu2O-ZnS and Cu2O-ZnO composites, can both enhance and suppress photocatalytic activity depending on the contacting planes at the heterojunction. Significantly, Cu2O photocatalytic activity can be greatly enhanced by functionalizing with conjugated molecules such as 4-nitrophenylacetylene (4-NA) to tune the surface band structure. This can turn the inactive cubes to possess a superior photocatalytic activity. Recently, Cu2O rhombic dodecahedra with and without 4-NA modification have been employed in photocatalytic hydroxylation of boronic acids, aryl sulfide oxidation, and amine coupling. SrTiO3 truncated rhombic dodecahedra were also found to be effective in amine coupling. Oxidative cyclization of thioamides is the latest example of surface control to photocatalytic organic transformations.

Erythrosine B Loaded Sulfone Conjugated Pyrene-Based Covalent Organic Framework as a Photocatalytic Tool for Oxidative Thioamide Cyclization

Erythrosine B Loaded Sulfone Conjugated Pyrene-Based Covalent Organic Framework as a Photocatalytic Tool for Oxidative Thioamide Cyclization

Transcriptional dynamic changes in energy metabolism, protein synthesis and cell cycle regulation reveal the biological adaptation mechanisms of juvenile Acrossocheilus wenchowensis under acute temperature changes

In recent years, frequent acute temperature changes have posed a serious threat to the physiology and survival of fish. This study utilized RNA-Seq technology to analyze the transcriptional dynamics in the muscle tissues of Acrossocheilus wenchowensis under various acute temperature conditions (16◦C, 20◦C, 24◦C, 28◦C and 32◦C). Through comprehensive analysis, we identified 11509 differentially expressed genes (DEGs), a gene set (profiles 19) that was significantly up-regulated with increasing temperature, and two weighted gene co-expression network analysis (WGCNA) modules that were significantly correlated with acute temperature changes. Furthermore, we identified 28 transcription factors that are pivotal in oxidative stress and energy metabolism under acute temperature changes. Our results showed that, compared to the control group (24°C), KEGG functional enrichment analysis revealed significant enrichment of DEGs in the cell cycle, DNA replication, and p53 signaling pathway, with an overall trend of suppressed expression. This indicates that maintaining cell stability and reducing cell damage is an effective adaptive mechanism for A. wenchowensis to cope with acute temperature changes. Through STEM analysis and the black WGCNA module associated with high-temperature stress, we identified significant up-regulation of pathways and hub genes related to energy metabolism including oxidative phosphorylation, TCA cycle, purine metabolism, and glutathione metabolism, as well as the central roles of signal transduction pathways such as MAPK signaling pathway and AMPK signaling pathway, which synergistically regulate energy production. Under acute low-temperature stress, the turquoise WGCNA module highlighted significant up-regulation of hub genes associated with Ribosomal and Spliceosomal pathways related to protein synthesis and processing, as well as activation of calcium signaling pathways, which plays an important role in maintaining cellular function during low-temperature adaptation. These findings provide a critical theoretical and molecular basis for the adaptation of eurythermal fish to rapid temperature changes.

Role of Prior Cyclic Oxidation on Tensile Deformation Behaviour of IN 713 C Alloy

Role of Prior Cyclic Oxidation on Tensile Deformation Behaviour of IN 713 C Alloy