Oxidative Cyclization Research Articles

Design of a packed bed chemical looping (unmixed) combustion reactor for the application of heating liquid: A theoretical study

AbstractA packed bed reactor (PBR)‐based chemical looping combustion (CLC), also referred to as unmixed combustion (UMC), was reported as an alternative to fire in the literature. In this process, the oxygen carriers undergo oxidation and reduction reactions in alternate cycles using air and fuel as the reactive gases, respectively. The energy generated in these reactions can radially be transferred for applications like heating air which was successfully demonstrated. The results showed that 85–95% of the generated energy can radially be transferred while maintaining sustained combustion in the bed (at temperatures between 723 and 1173 K). While extending its application for heating liquids like water, it was found in the modeling and simulation study that the existing design resulted in quenching of the bed below 773 K in the oxidation cycle and achieving sustained combustion was not possible for all practical ranges of operating parameters. Hence it was decided to modify the existing system by increasing the volume ratio of the annular bed to the liquid section. Theoretical estimations revealed that increasing this ratio by four times or higher can result in maintaining sustained combustion conditions in the bed while having continuous radial heat transfer to the water flowing in the laminar range. The general guidelines for designing a UMC‐based liquid heating system were then prepared and used to propose a new design for water heating. The modeling and simulation studies for this proposed design also indicated that it is a feasible design. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Effect of Y Content on Precipitation Behavior, Oxidation and Mechanical Properties of As-Cast High-Temperature Titanium Alloys

To improve the heat resistance of titanium alloys, the effects of Y content on the precipitation behavior, oxidation resistance and high-temperature mechanical properties of as-cast Ti-5Al-2.75Sn-3Zr-1.5Mo-0.45Si-1W-2Nb-xY (x = 0.1, 0.2, 0.4) alloys were systematically investigated. The microstructures, phase evolution and oxidation scales were characterized by XRD, Laser Raman, XPS, SEM and TEM. The properties were studied by cyclic oxidation as well as room- and high-temperature tensile testing. The results show that the microstructures of the alloys are of the widmanstätten structure with typical basket weave features, and the prior β grain size and α lamellar spacing are refined with the increase of Y content. The precipitates in the alloys mainly include Y2O3 and (TiZr)6Si3 silicide phases. The Y2O3 phase has specific orientation relationships with the α-Ti phase: (002)Y2O3 // (1¯1¯20)α-Ti, [110]Y2O3 // [4¯401]α-Ti. (TiZr)6Si3 has an orientation relationship with the β-Ti phase: (022¯1¯)(TiZr)6Si3 // (011)β-Ti, [1¯21¯6](TiZr)6Si3 // [044¯]β-Ti. The 0.1 wt.% Y composition alloy has the best high-temperature oxidation resistance at different temperatures. The oxidation behaviors of the alloys follow the linear-parabolic law, and the oxidation products of the alloys are composed of rutile-TiO2, anatase-TiO2, Y2O3 and Al2O3. The room-temperature and 700 °C UTS of the alloys decreases first and then increases with the increase of Y content; the 0.1 wt.% Y composition alloy has the best room-temperature mechanical properties with a UTS of 1012 MPa and elongation of 1.0%. The 700 °C UTS and elongation of the alloy with 0.1 wt.% Y is 694 MPa and 9.8%, showing an optimal comprehensive performance. The UTS and elongation of the alloys at 750 °C increase first and then decrease with the increase of Y content. The optimal UTS and elongation of the alloy is 556 MPa and 10.1% obtained in 0.2 wt.% Y composition alloy. The cleavage and dimples fractures are the primary fracture mode for the room- and high-temperature tensile fracture, respectively.

Stem Cell and Oxidative Stress-Inflammation Cycle.

Under a variety of physical and experimental settings, stem cells are able to self-renew and differentiate into specialized adult cells. MSCs (mesenchymal stromal/stem cells) are multipotent stem cells present in a wide range of fetal, embryonic, and adult tissues. They are the progenitors of a variety of specialized cells and are considered crucial tools in tissue engineering. MSCs, derived from various tissues, including cord blood, placenta, bone marrow, and dental tissues, have been extensively examined in tissue repair, immune modulation, etc. Increasing the vitality of MSCs and restoring cellular mechanisms are important factors in treatment success. Oxidative stress harms cellular molecules such as DNA, proteins, and lipids due to the overproduction of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in cells and tissues or insufficiency of antioxidant systems that can inactivate them. Oxidative stress has a close link with inflammation as a pathophysiological process. ROS can mediate the expression of proinflammatory genes via intracellular signaling pathways and initiate the chronic inflammatory state. At the same time, inflammatory cells secrete a large number of reactive species that cause increased oxidative stress at sites of inflammation. In inflammatory diseases, the differentiation of stem cells and the regenerative and wound healing process can be affected differently by the increase of oxidative stress. Recent studies have indicated that dental pulp stem cells (DPSCs), as a resource of adult stem cells, are an attractive option for cell therapy in diseases such as neurological diseases, diabetes, cardiological diseases, etc., as well as its treatment potential in pulp inflammation. The future of oxidative stressinflammation cycle and/or ageing therapies involves the selective elimination of senescent cells, also known as senolysis, which prevents various age-related diseases. Most pathologies are implicated on the effects of ageing without exerting undesirable side effects.

On Water Synthesis of 3-Aryl-1,2,4-Triazolo[4,3-a]Pyridines Using Iodobenzene Diacetate (IBD)

Abstract: An iodobenzene diacetate (IBD)-mediated simple and green method was determined for the intramolecular oxidative cyclization of 3-aryl-2-pyridiylhydrazones of different aromatic aldehydes in an aqueous medium at room temperature. This efficient strategy provides a route to the synthesis of 3-aryl-1,2,4-triazolo[4,3-a]pyridines in water which eliminates the requirement to use costly and unsafe volatile organic solvents. All reactions were carried out by just stirring the reaction components in water at room temperature. This protocol provides a wide substrate scope and good functional group tolerance.

Elemental Sulfur and Its Isotopic Composition in the Black Sea Water

As one of the main intermediate products of hydrogen sulfide oxidation, elemental sulfur plays an important indicator role in understanding the oxidative cycle of sulfur in the water of anoxic basins. The distribution of elemental sulfur in the water column of the Black Sea at stations located in the area of the continental slope is considered. For the first time, the concentration distributions of two forms of elemental sulfur depending on the depth in the Black Sea water were obtained: suspended elemental sulfur with a fraction of more than 0.45 μm (S0) and zero-valency sulfur (ZVS), which includes the sum of elemental sulfur (suspended and colloidal) and polysulfide sulfur. In the upper anoxic waters, the concentration of S0 noticeably increases (almost 200 times relative to the depth of 400 m) with an increase in the concentration of hydrogen sulfide and the density of water. At depths of more than 250 m, the concentration of both forms of sulfur remains almost constant (ZVS = 0.21 ± 0.03 µmol/kg, S0 = 0.05 ± 0.01 µmol/kg). A sharp increase in the concentration of S0 at the depths of 150–250 m is associated with the oxidation of hydrogen sulfide due to bacterial anoxygenic photosynthesis after sampling. The value of δ34S(ZVS) was determined in the waters of two stations Ash-26 and 149 at the depths of 450 and 600 m, respectively, which turned out to be +2.2‰ higher than δ34S(Н2S) from the same depths, which indicates the bacterial origin of elemental sulfur.

ELEMENTAL SULFUR AND ITS ISOTOPIC COMPOSITION IN THE BLACK SEA WATER

As one of the main intermediate products of hydrogen sulfide oxidation, elemental sulfur plays an important indicator role in understanding the oxidative cycle of sulfur in the water of anoxic basins. The distribution of elemental sulfur in the Black Sea water column at stations located in the area of the continental slope is considered. For the first time, the concentration distributions of two forms of elemental sulfur depending on the depth in the Black Sea water were obtained: suspended elemental sulfur with a fraction of more than 0.45 μm (S0) and zero valency sulfur (ZVS), which includes the sum of elemental sulfur (suspended and colloidal) and polysulfide sulfur. In the upper anoxic waters, the concentration of S0 noticeably increases (almost 200 times relative to the 400 m depth) with an increase in the concentration of hydrogen sulfide and the density of water. At depths of more than 250 m, the concentration of both forms of sulfur remains almost constant (ZVS = 0.21 ± ± 0.03 µmol/kg, S0 = 0.05 ± 0.01 µmol/kg). A sharp increase in the concentration of S0 at the depths of 150–250 m is associated with the oxidation of hydrogen sulfide due to bacterial anoxygenic photosynthesis after sampling. The value of δ34S(ZVS) was determined in the waters of two stations Ash-26 and 149 at the depths of 450 and 600 m respectively, which turned out to be +2.2‰ higher than δ34S(Н2S) from the same depths, which indicates the bacterial origin of elemental sulfur.

GDF15 promotes weight loss by enhancing energy expenditure in muscle

Caloric restriction that promotes weight loss is an effective strategy for treating non-alcoholic fatty liver disease and improving insulin sensitivity in people with type 2 diabetes1. Despite its effectiveness, in most individuals, weight loss is usually not maintained partly due to physiological adaptations that suppress energy expenditure, a process known as adaptive thermogenesis, the mechanistic underpinnings of which are unclear2,3. Treatment of rodents fed a high-fat diet with recombinant growth differentiating factor 15 (GDF15) reduces obesity and improves glycaemic control through glial-cell-derived neurotrophic factor family receptor α-like (GFRAL)-dependent suppression of food intake4–7. Here we find that, in addition to suppressing appetite, GDF15 counteracts compensatory reductions in energy expenditure, eliciting greater weight loss and reductions in non-alcoholic fatty liver disease (NAFLD) compared to caloric restriction alone. This effect of GDF15 to maintain energy expenditure during calorie restriction requires a GFRAL–β-adrenergic-dependent signalling axis that increases fatty acid oxidation and calcium futile cycling in the skeletal muscle of mice. These data indicate that therapeutic targeting of the GDF15–GFRAL pathway may be useful for maintaining energy expenditure in skeletal muscle during caloric restriction.

Exploring the anticancer potential of thiadiazole derivatives of substituted thiosemicarbazones formed via copper‐mediated cyclization

A couple of N‐(4)‐morpholine/pyrrolidine‐substituted thiosemicarbazones (TSCs) of fluorene‐2‐carboxaldehyde (FM and FP), and their corresponding thiadiazoles (TDZs) (CFM and CFP), were synthesized and characterized (elemental analysis, ultraviolet–visible [UV–Visible], Fourier transform infrared [FT‐IR], nuclear magnetic resonance [NMR; 1H & 13C], high‐resolution mass spectrometry [HRMS], and single‐crystal X‐ray diffraction [SCXRD]) for the evaluation of their anticancer potential. The TDZs were obtained unexpectedly and are possibly formed via single‐step metal (copper)‐mediated oxidative cyclizations of the TSCs. The synthesized compounds are fairly stable in phosphate buffer at the biological pH of 7.4. The density functional theory [DFT] studies were performed to predict the optimized structures and physicochemical properties of these compounds. The compounds were further subjected to computational and experimental biomolecular investigations in order to evaluate their anticancer activity in detail. CFM had the most potent activity against human breast adenocarcinoma (MCF‐7) and human urinary bladder (T24) cancer cells, with IC50 values of 12.00 and 24.80 μM, respectively. In contrast, CFM had negligible cytotoxicity (IC50 = 98.70 μM) against kidney epithelial cells extracted from an African green monkey (Vero) normal cells. This outcome was preferable to that of the widely used medicine Cisplatin. Molecular docking studies were performed with the breast cancer protein “cytochrome P450 1A1” (CYP1A1) and bovine serum albumin (BSA) to predict how effectively the compounds bind to the receptor. The ADMET findings suggest that these compounds have considerable drug‐likeness and oral bioavailability. These insights may open the door for additional medical research into the bioactivities of TSCs and TDZs produced from bioactive carbonyl compounds.

A metabolite specific 3D stack-of-spirals bSSFP sequence for improved bicarbonate imaging in hyperpolarized [1-13C]Pyruvate MRI

13C-bicarbonate is a crucial measure of pyruvate oxidation and TCA cycle flux, but is challenging to measure due to its relatively low concentration and thus will greatly benefit from improved signal-to-noise ratio (SNR). To address this, we developed and investigated the feasibility of a 3D stack-of-spirals metabolite-specific balanced steady-state free precession (MS-bSSFP) sequence for improving the SNR and spatial resolution of dynamic 13C-bicarbonate imaging in hyperpolarized [1-13C]pyruvate studies. The bicarbonate MS-bSSFP sequence was evaluated by simulations, phantoms studies, preclinical studies on five rats, brain studies on two healthy volunteers and renal study on one renal cell carcinoma patient. The simulations and phantom results showed that the bicarbonate-specific pulse had minimal perturbation of other metabolites (<1%). In the animal studies, the MS-bSSFP sequence provided an approximately 2.6–3 × improvement in 13C-bicarbonate SNR compared to a metabolite-specific gradient echo (MS-GRE) sequence without altering the bicarbonate or pyruvate kinetics, and the shorter spiral readout in the MS-bSSFP approach reduced blurring. Using the SNR ratio between MS-bSSFP and MS-GRE, the T2 values of bicarbonate and lactate in the rat kidneys were estimated as 0.5 s and 1.1 s, respectively. The in-vivo feasibility of bicarbonate MS-bSSFP sequence was demonstrated in two human brain studies and one renal study. These studies demonstrate the potential of the sequence for in-vivo applications, laying the foundation for future studies to observe this relatively low concentration metabolite with high-quality images and improve measurements of pyruvate oxidation.

Cycloadditions and Cyclization Reactions via Post-Synthetic Modification and/or One-Pot Methodologies for the Stabilization of Imine-Based Covalent Organic Frameworks

Interest in covalent organic frameworks as high-value materials has grown steadily since their development in the 2000s. However, the great advantage that allows us to obtain these crystalline materials—the reversibility of the bonds that form the network—supposes a drawback in terms of thermal and chemical stability. Among the different strategies employed for the stabilization of imine-based Covalent Organic Frameworks (COFs), cycloaddition and other related cyclization reactions are especially significant to obtain highly stable networks with extended π-delocalization and new functionalities, expanding even further the potential application of these materials. Therefore, this entry gathered the most recent research strategies for obtaining stable COFs by means of cyclization reactions, including the Povarov reaction and intramolecular oxidative cyclization reactions as well as some other recent innovative approaches.

Metal-Free Eliminative C-H Arylthiolation of 2H-Imidazole N-Oxides with Thiophenols

A synthetic strategy based on reactions of cyclic imine oxides, namely 2H-imidazole 1-oxides, with thiophenols mediated by acetyl chloride was successfully applied as a convenient tool to obtain a series of novel azaheterocyclic molecules, including water-soluble hydrochloride forms. Optimized reaction conditions found herein for the nucleophilic substitution of hydrogen (SNH) in non-aromatic azaheterocyclic substrates via the “addition-elimination” (SNH AE) scheme enabled 15 arylthiolated 2H-imidazoles to be prepared in yields of up to 90%. The developed methodology discloses an original synthetic way to obtain numerous azaheterocyclic molecules, which are of interest in the field of medicinal chemistry and materials science.

Modulating the electronic structure of NiFe hydroxide by Zr doping enables industrial-grade current densities for water oxidation

NiFe layered double hydroxide (LDH) is a non-noble benchmark catalyst for oxygen evolution reaction (OER). However, the mechanism of enhancing catalytic activities via incorporating foreign elements is still not resolved. Herein, we modulate the electronic structure of NiFe LDH by introducing high-valence Zr4+ to synergistically improve catalytic activity. NiFeZr LDH requires overpotential of only 182 mV at 10 mA cm−2 with Tafel slope of 38.6 mV dec−1. Impressively, it delivers 2000 mA cm−2 at only 314 mV and has robust durability over 750 h. Operational Raman analysis reveals that the electron transfer after incorporating Zr4+ inhibits oxidation of Ni2+ ions and restrains phase transition from active β-NiOOH to γ-NiOOH during OER process. Guided by density functional theory (DFT) computations, Zr4+ modulator promotes the rate-determining step from OH* to O* via optimizing the oxidation cycle at Fe active sites. This work provides a route for advancing electrocatalysts to meet industrial standards.

Synergistic activation of persulfate by ultrasound/PbO2 anodic oxidation system for effective degradation of naproxen, a toxic and bio-recalcitrant pollutant: Process optimization and application for pharmaceutical wastewater

Naproxen (NPX) is a widely used pain reliever that conventional treatment systems are unable to fully mineralize its residues in wastewater. The aim of this study is to develop a synergistic persulfate activation system based on ultrasound/PbO2 anodic oxidation process (US/PS/AO) for effective degradation of NPX and improving the biodegradability of pharmaceutical wastewater. PbO2 electrocatalyst was prepared by anodic deposition and then its characteristics were determined by FESEM, EDX and XRD techniques. Optimizing the effect of independent variables on NPX removal was done using an CCD method. The performance of the optimized US/PS/AO process for NPX degradation and TOC mineralization after 60 min of reaction was 98.5 % and 73.6 %, respectively. The reusability of the PbO2 electrocatalyst was maintained above 97 % in ten continuous oxidation cycles for NPX degradation. Also, the cumulative concentration of leaked lead (53 μg L−1) was within the permitted standard for discharging wastewater into the river. Using HPLC-mass spectrometer data, possible pathways for NPX mineralization were suggested. The biodegradability of pharmaceutical wastewater with the optimized US/PS/AO and PS/AO processes increased to above 0.4 after 100 and 150 min of treatment, respectively. However, the total energy consumption in the PS/AO process (US power = 0, EC = 83 kWh kg−1 COD) is significantly lower than the US/PS/AO (US power = 100 W, EC = 982 kWh kg−1 COD). The findings of the present study can contribute to the development of a cheap, safe, and effective integrated AOP for the treatment of pharmaceutical wastewater containing non-biodegradable compounds.

RETRACTED: The Effect of Treatment Temperature on Microstructure and Mechanical Behavior of a Fine-Grained YSZ–NiO(Ni) Anode Material

Reduction–oxidation (redox) cycling of a solid oxide fuel cell (SOFC) due to leakage of a fuel or standby and shutdown cycling is an issue that has attracted the attention of many research groups for a long time. The researchers mainly note the harmful effects of redox cycling on the microstructure of SOFC constituents and search for ways to mitigate or diminish them. The purpose of this study was to use reduction and oxidation stages in an appropriate mode as a positive preconditioning to improve redox cycling stability of Ni-containing SOFC anode materials. The redox treatment was applied to YSZ–NiO(Ni) anode substrate specimens at 600 °C and 800 °C. The mechanical tests (flexural strength, microhardness, and fracture toughness) were performed on these specimens and the results were compared to those for as-sintered and one-time reduced specimens. Microstructure and fracture surface morphology of material in corresponding modes were analyzed. The main findings were summarized as follows: (i) Redox treatment at 600 °C provides an increase in flexural strength and electrical conductivity of YSZ–NiO(Ni) anode cermets; (ii) the treatment at 800 °C causes formation of a gradient microstructure with lateral cracks that result in a significant decrease in flexural strength; (iii) the mode of redox treatment at 600 °C for 4 h in Ar–5% H2/air atmosphere provides an increase in flexural strength of YSZ–NiO(Ni) anode cermets (up to 127 ± 4 MPa), while electrical conductivity was provided at a comparatively high level (7 × 105 S/m).

Regio- and Chemoselective Formal (4+1) Carbocyclization of Chalcones with Internal Alkynes via Rhodium(III) Catalysis.

A rhodium(III)-catalyzed oxidative cyclization of chalcones with internal alkynes is reported, generating biologically important 3,3-disubstituted 1-indanones along with reusable aromatic aldehydes. This transformation features unique (4+1) reaction mode, excellent regioselectivity in alkyne insertion, broad substrate scope, allows for the construction of quaternary carbon centers, and is scalable. Steric hindrance from substrate and ligand probably controls the chemoselectivity of this carbocyclization. Importantly, this discovery enables a practical two-step protocol switching the overall reaction of acetophenones with internal alkynes from a (3+2) to a (4+1) annulation.

Regio‐ and Chemoselective Formal (4+1) Carbocyclization of Chalcones with Internal Alkynes via Rhodium(III) Catalysis

AbstractA rhodium(III)‐catalyzed oxidative cyclization of chalcones with internal alkynes is reported, generating biologically important 3,3‐disubstituted 1‐indanones along with reusable aromatic aldehydes. This transformation features unique (4+1) reaction mode, excellent regioselectivity in alkyne insertion, broad substrate scope, allows for the construction of quaternary carbon centers, and is scalable. Steric hindrance from substrate and ligand probably controls the chemoselectivity of this carbocyclization. Importantly, this discovery enables a practical two‐step protocol switching the overall reaction of acetophenones with internal alkynes from a (3+2) to a (4+1) annulation.

Trichalcogenasupersumanenes and its concave-convex supramolecular assembly with fullerenes

Synthesis of buckybowls have stayed highly challenging due to the large structural strain caused by curved π surface. In this paper, we report the synthesis and properties of two trichalcogenasupersumanenes which three chalcogen (sulfur or selenium) atoms and three methylene groups bridge at the bay regions of hexa-peri-hexabenzocoronene. These trichalcogenasupersumanenes are synthesized quickly in three steps using an Aldol cyclotrimerization, a Scholl oxidative cyclization, and a Stille type reaction. X-ray crystallography analysis reveals that they encompass bowl diameters of 11.06 Å and 11.35 Å and bowl depths of 2.29 Å and 2.16 Å for the trithiasupersumanene and triselenosupersumanene, respectively. Furthermore, trithiasupersumanene derivative with methyl chains can form host-guest complexes with C60 or C70, which are driven by concave-convex π ⋯ π interactions and multiple C–H ⋯ π interactions between bowl and fullerenes.

Iron-Catalyzed Oxidative Cyclization of 2-Amino Styrenes with Alcohols and Methyl Arenes for the Synthesis of Polysubstituted Quinolines.

Herein, we present the iron-catalyzed oxidative cyclization of alcohol/methyl arene with 2-amino styrene to synthesize polysubstituted quinoline. Low-oxidation level substrates such as alcohols and methyl arenes are converted to aldehydes in the presence of an iron catalyst and di-t-butyl peroxide. Then, the quinoline scaffold is synthesized through imine condensation/radical cyclization/oxidative aromatization. Our protocol showed a broad substrate scope, and various functionalization and fluorescence applications of quinoline products demonstrated its synthetic ability.

Mitochondrial reprogramming in peripheral blood mononuclear cells of patients with glycogen storage disease type Ia

BackgroundGlycogen storage disease type Ia (GSDIa) is an inborn metabolic disorder caused by the deficiency of glucose-6-phospatase-α (G6Pase-α) leading to mitochondrial dysfunction. It remains unclear whether mitochondrial dysfunction is present in patients’ peripheral blood mononuclear cells (PBMC) and whether dietary treatment can play a role. The aim of this study was to investigate mitochondrial function in PBMC of GSDIa patients.MethodsTen GSDIa patients and 10 age-, sex- and fasting-time matched controls were enrolled. Expression of genes involved in mitochondrial function and activity of key fatty acid oxidation (FAO) and Krebs cycle proteins were assessed in PBMC. Targeted metabolomics and assessment of metabolic control markers were also performed.ResultsAdult GSDIa patients showed increased CPT1A, SDHB, TFAM, mTOR expression (p < 0.05) and increased VLCAD, CPT2 and citrate synthase activity in PBMC (p < 0.05). VLCAD activity directly correlated with WC (p < 0.01), BMI (p < 0.05), serum malonycarnitine levels (p < 0.05). CPT2 activity directly correlated with BMI (p < 0.05).ConclusionMitochondrial reprogramming is detectable in PBMC of GSDIa patients. This feature may develop as an adaptation to the liver enzyme defect and may be triggered by dietary (over)treatment in the frame of G6Pase-α deficiency. PBMC can represent an adequate mean to assess (diet-induced) metabolic disturbances in GSDIa.

NHPI/O2‐Mediated Electrochemical Intermolecular Cyclization/Dehydrogenation for the Construction of Polycyclic Quinazolinones

AbstractHerein, an eco‐friendly and atom‐economical electrochemical methodology with isatins and 1,2,3,4‐tetrahydroisoquinolines through NHPI/O2‐mediated intermolecular oxidation/annulation is disclosed, leading to a variety of polycyclic quinazolinones in 46–82% yields. This oxidative cyclization proceeded in transition metal‐ and strong oxidant‐free conditions and generated H2 and CO2 as byproducts. Additionally, late‐stage functionalization and broad substrate scope demonstrated the synthetic usefulness of this protocol.