Chemistry and Materials Science

Abstract: [¹¹C]Choline ([¹¹C]CHO) has reemerged as a radiopharmaceutical tracer for positron emission tomography (PET) diagnostics and optimized synthesis setups are thus needed to meet the increased demand, often on existing production lines. Originally, [¹¹C]CHO has experienced a decline in use for PET diagnostics, particularly in prostate cancer imaging due to radiopharmaceuticals with higher target specificity. However, recent studies have demonstrated superior sensitivity and diagnostic accuracy of [¹¹C]CHO for localizing autonomous adenomas in primary hyperparathyroidism (PHPT) compared to conventional ⁹⁹ᵐTc-sestamibi scintigraphy. The PET-scan is used prior to surgery, but not for the diagnosis of PHPT. The patient compliance is high due to the relatively short time in the scanner. With this renewed clinical relevance, optimization of [¹¹C]CHO synthesis is warranted, as standard production protocols typically yield only 2.5–3.0 GBq. In this study, three critical steps in the synthesis process on a TracerMaker module were systematically evaluated and optimized. (1) Extending the irradiation time from 25 to 42 minutes produced no significant increase in radiochemical yield (RCY). (2) Increasing the precursor, dimethylaminoethanol (DMAE) loading volume to 150 µL divided across two serially connected Sep-Pak Accell CM Plus Light cartridges resulted in a twofold RCY increase but also elevated residual DMAE levels in the final product. (3) Increasing washing volumes of ethanol and water did not improve purification efficiency; however, replacing the two stacked cartridges (2 × 130 mg) with a single cartridge containing a higher sorbent mass (360 mg) achieved effective DMAE removal while maintaining high RCY. These findings demonstrate a practical route for optimizing [¹¹C]CHO synthesis to meet the growing clinical demand of [¹¹C]CHO for imaging of PHPT.

Abstract: The growing demand for efficient and sustainable materials for air purification has stimulated interest in activated carbons derived from renewable biomass resources. In this study, activated carbons were prepared from rice husk, wheat straw, sawdust, and walnut shells and systematically investigated as sorbents for toxic gases and volatile organic compounds. The materials were characterized using nitrogen and water vapour sorption isotherms, scanning electron microscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, and energy-dispersive X-ray analysis to evaluate their textural properties, morphology, thermal stability, and surface chemistry. The results showed that the precursor type strongly influences the pore structure and functional group composition of the activated carbons. Wheat straw and Rice husk–derived activated carbons exhibited the highest total pore volume and a well-developed porous structure, together with a high content of oxygen- and silicon-containing elements. Gas breakthrough experiments with different probes showed that wheat straw–derived activated carbon excels in VOC removal due to its highly microporous structure. In contrast, rice husk–derived activated carbon displays strong affinity toward inorganic gases such as NH₃ and, after urea modification, achieves enhanced performance for SO₂. These results underscore the versatility and practical applicability of carbon materials obtained from plant residues.

Abstract: A multi-analytical study was conducted to investigate the deterioration mechanisms affecting the stone materials of the Arca di Cansignorio della Scala (Verona, Italy) and to identify the residual traces of polychromy and gilding. The investigation combined macroscopic mapping, stratigraphic sampling, optical microscopy (OM), environmental scanning electron microscopy (ESEM) coupled with energy-dispersive spectroscopy (EDXS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and ion chromatography (IC). The monument, mainly carved in Candoglia marble, exhibits three principal weathering typologies: (i) meteoric washing associated with marble decohesion, (ii) grey deposits (dirt accumulation areas); and (iii) sulphation-related black crust formation (dirt wetting areas). In addition, severe mechanical damage is as-sociated with early 20th-century structural consolidation using embedded iron bars, whose corrosion-induced volumetric expansion generated vertical fissures. Strati-graphic analyses revealed the presence of original azurite-based polychrome, proteina-ceous and lipidic binders, lead white preparatory layers, and multiple gold leaf applica-tions of gold leaf. The study highlights the interaction between environmental exposure, atmospheric pollution, material incompatibility resulting from past restorations cam-paigns, and the preservation state of the surviving decorative painted layers.

Abstract: The escalating global crisis of water scarcity, exacerbated by the increasing prevalence of heavy metal contamination from anthropogenic activities, necessitates the development of innovative and sustainable remediation technologies. Recognizing the inherent metal-binding capabilities of Cannabis sativa L. (hemp), this study introduces a novel approach for copper(II) ion removal from aqueous solutions. We investigated the synergistic potential of combining hemp-derived cannabinoids with chitosan-polyvinyl alcohol (PVA) hydrogels to create a bio-based adsorbent. Hemp oil, rich in cannabinoids, was incorporated into chitosan-PVA hydrogels synthesized to enhance mechanical stability. The resulting hemp hydrogels (HHGs) were characterized using Fourier Transform Infrared Spectroscopy (FTIR), confirming the integration of the oil within the hydrogel matrix. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis of copper-contaminated solutions treated with HHGs over 24 hours demonstrated a reduction in copper ion concentration, suggesting a biosorption mechanism. Swelling studies revealed an inverse relationship between hemp oil content and water uptake capacity. Thermal studies showed excellent stability amongst gel types. This work establishes the feasibility of utilizing hemp-modified hydrogels as a promising avenue for heavy metal removal, paving the way for future optimization of these bio-composites in both drinking water purification and industrial wastewater treatment applications.

Abstract: Surface modification of zinc oxide nanoparticles (ZnO NPs) with organosilane capping agents represents an effective strategy to control their physicochemical and biological properties. In this work, we report for the first time the use of halogenosilanes, namely (3- chloropropyl)trimethoxysilane (CPTMS), (3-bromopropyl)trimethoxysilane (BPTMS) and (3-iodopropyl)trimethoxysilane (IPTMS), for the surface functionalization of ZnO NPs obtained by chemical precipitation. Structural and morphological characterization (PXRD, TEM, SEM-EDX and FTIR) confirmed successful surface modification and revealed a significant particle size reduction from ~31 nm for unmodified ZnO to ~8 nm for BPTMS-modified ZnO (ZnO_b). The biological evaluation showed that halogenosilane-modified ZnO NPs exhibit enhanced cytotoxic activity against prostate cancer cell lines (PC3 and 22Rv1), with ZnO_b displaying the highest activity, likely associated with improved cellular uptake and increased reactive oxygen species (ROS) generation. In contrast, antimicrobial assays revealed only moderate bactericidal effects against Escherichia coli and Staphylococcus aureus at relatively high concentrations (≥1250 µg mL⁻¹), while no significant activity was observed against Pseudomonas aeruginosa, Burkholderia contaminans or Candida spp. within the tested range. These findings suggest that halogenosilane functionalization modulates the biological profile of ZnO nanoparticles by enhancing anticancer effects while also influencing microbiocidal activity, highlighting the role of surface chemistry in tuning biological selectivity. The present study supports the concept that rational surface engineering of ZnO-based nanoplatforms can be exploited to favor tumor-targeted activity over broad-spectrum antimicrobial effects, providing new perspectives for the design of application-oriented nanomaterials.

Abstract: Rapid detection and localization of liquid fuel spills is critical for first responders assessing fire and health hazards, yet current methods require ground-based sampling or specialized instrumentation, limiting their practicality for wide-area emergency response. We present a drone-based passive colorimetric sensor system using test strips impregnated with Nile red, similar to colored confetti. Nile red is a solvatochromic dye that undergoes distinct visible color transitions upon exposure to different liquids. The dye is embedded within a polymer matrix that minimizes leaching while providing high optical contrast between dry, water-exposed, and fuel-exposed states. The sensor strips exhibit solvent-specific colorimetric responses within one minute of exposure, readily detectable by standard RGB cameras mounted on unmanned aerial vehicles (UAV) at altitudes up to 50 m. Automated classification was validated at 20 m altitude, enabling remote surveillance of contaminated surfaces without specialized equipment. Color-corrected image analysis using Calibrite ColorChecker calibration ensures reliable interpretation under variable field illumination (625–77,000 lux). Systematic laboratory evaluation of twelve fossil and bio-derived fuels revealed characteristic hue shifts that clearly discriminate ethanol-containing gasoline blends from diesel-range fuels. Field validation confirmed localization and classification of fuel-exposed sensors, achieving F1 scores of 0.94 for gasoline and 0.98 for diesel detection with no false positives in the tested scenarios. This cost-effective and scalable approach provides actionable information on both contamination location and fuel type, crucial for rapid hazard assessment in emergency response scenarios.

Abstract: Whether copper fundamentally alters Mo-centered redox thermodynamics or mainly tunes hydrogen adsorption in Ni–Mo electrocatalysts under alkaline hydrogen evolution reaction (HER) conditions remains unresolved. Density functional theory calculations combined with a field-corrected computational hydrogen electrode framework are used to evaluate the thermodynamic stability of H₃Mo, H₃MoOH, H₂Mo(OH)₂, and MoO(OH)₃ on Cu(111) and Ni(111) and to construct surface Pourbaix diagrams under electrochemical conditions. The results show that substrate identity reorganizes the redox stabilization hierarchy of these Mo intermediates. Across the examined conditions, at least one of H3Mo, H3MoOH, or MoO(OH)₃ is thermodynamically favored over H₂Mo(OH)₂ on both surfaces. However, only Cu(111) exhibits measurable pH-dependent free-energy shifts, reaching 0.28 eV on the reversible hydrogen electrode scale. The magnitude of this electrostatic modulation is comparable to the intrinsic substrate-dependent relative Gibbs free-energy differences, suggesting that Cu reshapes Mo redox thermodynamics rather than merely weakening hydrogen binding strength. Electronic structure and vibrational analyses further show that Cu(111) preferentially weakens Mo–O interactions, whereas Ni(111) more strongly perturbs Mo–H bonding in hydrogen-rich complexes. Overall, these results establish that substrate identity governs the electrostatic modulation of Mo redox thermodynamics under alkaline HER conditions and provide a mechanistic insight into substrate effects relevant to Cu-containing Ni–Mo systems.

Abstract: The Fenton reaction remains one of the most widely investigated advanced oxidation processes for wastewater treatment due to its ability to generate highly reactive oxygen species capable of degrading persistent organic pollutants. However, classical homoge-neous Fenton systems suffer from significant limitations, including narrow pH applica-bility, iron sludge generation, and poor catalyst reusability. In response, extensive research has been devoted to the development of heterogeneous and advanced Fenton-like catalysts that address these challenges while improving catalytic efficiency and operational stabil-ity. This review provides a comprehensive analysis of the evolution of Fenton catalysis, from classical homogeneous systems to modern advanced materials, including nanostructured catalysts, carbon-based Fe–N–C systems, metal–organic frameworks, and single-atom catalysts. Particular emphasis is placed on key performance parameters such as catalytic activity, manufacturability, stability, and catalyst lifespan. A critical comparison of these systems highlights the trade-offs between activity, cost, and scalability, demonstrating that the most advanced catalysts do not necessarily offer the best practical performance. A dedicated life cycle assessment perspective is included, focusing on catalyst lifespan, reuse efficiency, and iron leaching, providing quantitative insights into long-term sus-tainability. The analysis reveals that while advanced catalysts significantly improve cu-mulative catalytic output, their environmental and economic viability depends on synthe-sis complexity and durability under realistic conditions. Finally, current challenges and future directions are discussed, including the need for scalable synthesis methods, improved mechanistic understanding, and integration into hybrid treatment systems. This review aims to bridge the gap between fundamental re-search and practical application, offering guidance for the design of next-generation sus-tainable Fenton catalysts for wastewater treatment.

Abstract:

The viscosity stability of the polymer solution is one of the challenges in enhancing oil recovery and zwitterionic copolymer presents excellent viscosity stability and emulsification performance, enabling effective control the oil/water interface mobility and enhancing oil recovery. Herein, a zwitterionic copolymer (P(AM/AMBS/MAPTAC)) containing sulfonic acid group and quaternary amine group was synthesized by segmentation initiation with AM, AMBS and MAPTAC as monomers. The chemical structure of P(AM/AMBS/MAPTAC) was confirmed by FTIR and ¹H NMR. The M_w value of (P(AM/AMBS/MAPTAC)) was 9.91×10⁶, and the apparent viscosity of the solution of 2000 mg/L solution was 24.92 mP·s at 60 ℃ in the 5000 mg/L salt solution. P(AM/AMBS/MAPTAC) with the sulfonic acid group and the quaternary amine group exhibits outstanding salt tolerance and shear resistance. When the salinity was 10000 mg/L and the shear rate was 300 s^-1, the apparent viscosity and the viscosity reduction rates for the P(AM/AMBS/MAPTAC) solution were 23.45 mP·s and 69.23 %, respectively. Moreover, P(AM/AMBS/MAPTAC) exhibited higher emulsion property and higher oil-water interface thickness than HPAM and SPAM because of the synergistic effect of sulfonic acid and quaternary amine groups in the P(AM/AMBS/MAPTAC) molecule. The polymer flooding and the alkali-surfactant-polymer flooding formed by P(AM/AMBS/MAPTAC) had high chemical oil recovery and the oil displacement efficiency was higher than HPAM and SPAM in the polymer flooding and the alkali-surfactant-polymer flooding systems.

Abstract: The therapeutic monoclonal antibody bevacizumab is typically purified using Protein-A affinity chromatography, a highly effective but costly method. As a lower-cost alternative, affinity-based precipitation has been described to purify antibodies. Therefore, in this work, a precipitation protocol was developed for bevacizumab purification using the branched peptide (Ac-PHQGQHIG-Ahx₃)2-K-Ahx₃-PHQGQHIG-NH₂, which contains the epitope PHQGQHIG responsible for interaction with bevacizumab. The peptide was synthesised by microwave-assisted solid-phase peptide synthesis employing LiCl as an additive to prevent aggregation and ensure high purity and yield. Three molecules of 6-aminohexanoic acid were introduced between each epitope branch as spacer arms to promote the formation of cyclic complexes. Bevacizumab purification from the cell-free culture broth was achieved through a fractional precipitation process. First, a negative precipitation step using (NH₄)₂SO₄ 1.18 M was performed to remove contaminants. Afterwards, 5 moles of peptide per mol of bevacizumab were added to the supernatant, together with additional (NH₄)₂SO₄ to reach a final concentration of 1.20 M. Under these conditions, bevacizumab was recovered in the precipitate with 98% purity and a yield of 73%. In addition to being recyclable, the peptide´s relative low production cost may enable the development of a single-use purification process, which would be particularly advantageous for biopharmaceutical manufacturing.

Abstract: Background/Objectives: Microbial resistance to antibiotics has become a major global public health problem, threatening the effectiveness of current therapeutic strategies. The present study seeks to investigate natural compounds originating from fungal sources for their ability to interfere with efflux pump–mediated resistance in multidrug-resistant (MDR) bacteria, with the overarching goal of uncovering new candidates for antimicrobial therapeutic development. A chemical investigation of the ethanol extract of Termitomyces clypeatus was carried out to isolate and identify its constituents. Methods: Structural elucidation of the isolated metabolites was achieved through 1D and 2D NMR spectroscopy supported by mass spectrometric data. The crude extract and the purified compounds were then evaluated for their antibacterial activities individually, in the presence of an efflux pump inhibitor, and in combination with three antibiotics, using standardized microdilution assays. Results: Chromatographic separation of the extract yielded eleven known compounds including three sphingolipids: (9Z,12Z)-N-(1,3,4-trihydroxyoctadecan-2-yl)octadeca-9,12-dienamide (1), 2-hydroxy-N-(1,3,4-trihydroxyoctadecan-2-yl)hexadecanamide (2), and cerebroside B (3); four steroids: ergosterol (4), cerevisterol (5), ergosterol peroxide (6), and 5α,6α-epoxy-(22E,24R)-ergosta-8(14),22-diene-3β,7α-diol (7); one alkaloid: piperine (8); one carbohydrate: D-mannitol (9); and two phthalates: dimethyl phthalate (10) and bis(2-ethylhexyl) terephthalate (11). GC–MS analysis led to the identification of eight fatty acid derivatives (12–19). Sub-fraction A, along with compounds 3, 4, and 8 exhibited notable antibacterial activity against some tested strains with MIC values of 64 μg/mL. These compounds were identified as substrates of bacterial efflux pumps, and their presence enhanced the antibacterial effects of ciprofloxacin, doxycycline, and amikacin. Conclusion: The findings of the present work indicate that Termitomyces clypeatus contains antibacterial compounds with potential therapeutic value, both as standalone agents and as adjuvants that enhance the activity of conventional antibiotics.

Abstract: In this study, extracts of metallurgical slags of the former lead plant in Shymkent and Zhezkent Mining and Processing Plant are used as a liquid mineral fertilizer for growing corn. Slag extraction was carried out by the method of chemical leaching with potassium sulfate and ammonia solution in hydrogen peroxide medium. Macro- and microelement analysis of extracts from slag was carried out. Among the obtained extracts, the slag extract of the second slag store of the former lead plant is the least toxic and the richest in macro- and microelements (27.605 Са 2+; 5.959 Mg2+; 423.751 Cu2+; 86.649 Zn2+; 5.567 Fe2+,3+; 22.652 Mn mg/L). The studied solution was diluted in the ratio of extract: distilled water 1:10 for the extract based on potassium sulfate and 1:200 for the extract based on ammonia and used to evaluate the initial development of seeds and yield of corn. Germination of seed corn and its development after 90 days did not differ from the control variant. The concentration of potentially toxic elements in the dry mass of the plant does not exceed the permissible concentration. The results showed the potential of safe application of this fertilizer in agriculture and rational utilization of industrial waste.

Abstract: Today, interest in natural remedies for biocontrol of crop pests is paramount. Punica granatum L. (pomegranate) is studied worldwide to obtain interesting bioactive compounds. Its anti-parasitic activity is associated with the presence of alkaloids in its roots. In this work, we explored the possibility of obtaining from P. granatum roots pelletierine-like alkaloids, which were extracted, characterized, isolated and used for the biocontrol of pests such as Spodoptera littoralis, Myzus persicae, Rhopalosiphum padi and Meloidogyne javanica. Two different extracts were obtained, characterised and quantified by GC-MS and LC-ESI-HRMS. In vitro assays of nematicidal activity were performed comparing the extracts with isopelletierine and pseudopelletierine as pure molecules. The results of these assays showed a difference in activity between iso- and pseudopelletierine, especially in terms of the nematocidal effect against M. javanica with isopelletierine being more active than pseudopelletierine. This leads us to conclude that only extracts from P. granatum roots with a high concentration of isopelletierine alkaloid can be used in effective pest control products.

Abstract: As the key enzyme catalyzing the final step in the biosynthesis of heme and chlorophyll, protoporphyrinogen oxidase (PPO) has become a crucial target for herbicide development. To date, more than 40 PPO-inhibiting herbicides have been developed, exhibiting multiple advantageous characteristics: they combine high efficacy with environmental friendliness, feature low effective concentrations, rapid action, long-lasting effects, and excellent control of both monocotyledonous and dicotyledonous weeds. In recent years, significant progress has been made in the structural biology of PPO—five crystal structures from tobacco, humans, and various bacteria have been resolved, most of which are presented as enzyme-inhibitor complexes. Although the development of such herbicides spans over five decades, novel PPO inhibitors still hold broad potential for innovation due to the resistance of early applied PPOs. This review systematically summarizes the three-dimensional structures of PPO from different sources, the interaction mechanisms between the enzyme and inhibitors, studies on quantitative structure-activity relationships of inhibitors, and outlines molecular design directions for the next generation of PPO inhibitors.

Abstract: This work demonstrates an efficient and reproducible method for the covalent biofunctionalization of epoxy solder mask surfaces on printed circuit boards (PCBs) produced using a conventional manufacturing process, enabling the implementation of capacitive biosensors without the need for any additional PCB fabrication steps and thereby supporting low-cost biosensing applications. Surface activation was achieved using 600 mM 3-mercaptopropionic acid (3-MPA) and 600 mM EDC/NHS, followed by immobilization of 600 µM bovine serum albumin (BSA) as a model protein, achieving spatial variability below 10%. This methodology can be directly applied to other proteins by simply substituting the biomolecule of interest. ATR-FTIR analysis confirmed successful chemical modification through the appearance of characteristic carboxyl and amide bands, while BCA assays verified effective protein attachment. The sensing performance of the functionalized surface was evaluated using electrochemical impedance spectroscopy on interdigitated PCB-based electrodes. A clear decrease in the impedance module was observed at 1 MHz after BSA immobilization and subsequent anti-BSA binding with a variation of 2826 ± 235 Ω and 4214 ± 239 Ω respectively (p < 0.001). Remarkably, anti-BSA was detected at concentrations as low as 10 ppb. These results highlight not only the strong biochemical activity and stability of the modified solder mask surface, but also its potential for scalable, robust, and cost-effective PCB-integrated biosensors for clinical biomarker detection and point-of-care diagnostics, as well as other widespread diagnostic and sensing applications.

Abstract: Development of new polymers, that cannot be achieved by using conventional catalysts has been the central research objective, and copolymerization is an effective strategy to modify the materials’ (thermal, physical, mechanical and electronic) properties. Modified half-titanocenes, Cp’TiX2(Y) (Cp’ = cyclopentadienyl; X = Cl, Me etc.; Y = anionic donor such as phenoxide, ketimide, amidinate etc.), are known to be the effective catalysts. This review introduces several selected efforts for efficient synthesis of ethylene copolymers containing cyclic olefins, biobased conjugated dienes, disubstituted α-olefins including effect of cocatalysts. Moreover, here introduces analysis using XAS (X-ray absorption spectroscopy), which has been recognized as powerful method providing direct information of the catalytically active species, such as coordination numbers and the distances of the coordinated atoms as well as oxidation state and the geometry of the metal centre in catalyst solution.

Abstract: Aldolases are powerful biocatalysts for the stereoselective formation of carbon–carbon bonds and are widely used in the synthesis of chiral intermediates for pharmaceutical applications. Among them, 2-deoxyribose-5-phosphate aldolase (DERA) has been extensively exploited for the preparation of the conserved side chain of statins. In this work, we report a novel chemoenzymatic approach for the synthesis of nucleobase-substituted lactol products as potential precursors of new statin analogues. A C49M variant of DERA from Pectobacterium atrosepticum (PaDERA C49M) was employed to catalyze sequential aldol additions using aldehyde-functionalized nucleobases as non-natural electrophilic substrates. The formation of nucleobase-containing lactols was confirmed, demonstrating for the first time the acceptance of nucleobase-derived aldehydes in DERA-catalyzed aldol reactions. This strategy provides access to structurally novel statin side-chain precursors and expands the synthetic potential of DERA toward the generation of new classes of bioactive compounds.

Abstract: A series of Fe-ZSM-5 catalysts with varying Fe loadings were synthesized via a hydrothermal method. Their catalytic performance was evaluated for the selective catalytic reduction (SCR) of NOx with ammonia. The catalyst with a Fe:Al molar ratio of 1:1 demonstrated the highest NOx conversion (99.9%) and exhibited a broader operating temperature window (240–390°C) compared to catalysts with other Fe/Al ratios. Characterization by X-ray diffraction (XRD),scanning electron microscopy(SEM), and X-ray photoelectron spectroscopy(XPS) confirmed that the incorporation of iron ions preserved the high crystallinity and MFI structure of the ZSM-5 zeolite. NH3-temperature-programmed desorption (NH3-TPD) profiles revealed the presence of two distinct acid sites at approximately 250 °C and 400 °C.

Abstract:

The photocatalytic dehydrogenative coupling of methanol to produce the high-value-added chemical ethylene glycol (EG) has garnered widespread attention owing to its environmental benignity and mild reaction conditions. The ternary metal sulfide Zn₂In₂S₅(ZIS), by virtue of its unique stoichiometric ratio, demonstrates a high intrinsic selectivity for the activation of the α-C-H bond in methanol. However, pristine ZIS faces the challenge of rapid recombination of photogenerated electron-hole pairs, which severely restricts its photocatalytic efficiency. In this study, the conductive polymer polyaniline (PANI) was successfully coupled with the ZIS photocatalyst via a simple one-step hydrothermal polymerization method to fabricate a series of PANI/ZIS nanocomposite photocatalysts. Systematic evaluation results indicate that the optimal catalyst, 7.5%-PANI/ZIS, exhibits exceptional catalytic performance under visible light, achieving an ethylene glycol generation rate as high as 4.87 mmol/g/h, representing a 6.76-fold enhancement over pristine ZIS (0.72 mmol/g/h). The significant performance enhancement is attributed to the synergistic effects of PANI and ZIS, which formed Type-II heterojunction effectively promotes the separation and transport of photogenerated charges and significantly reduces the charge transfer resistance. This research provides new insights into interfacial engineering based on conductive polymers and is of significant scientific importance for the high-value utilization of C1 small molecules.

Abstract: Three alloys, two based on cobalt and one on nickel, containing 5 or 10 wt.%Al for their resistance to hot oxidation, and Ta and C for forming TaC carbides for they creep–resistance at high temperature, were synthesized by casting. They were subjected to the control of their as–cast microstructures and to oxidation tests at 1200°C for 50 hours in a thermobalance. The initial microstructures of the two low Al alloys, both containing 5 wt.%Al, are not significantly modified by the Al introduction by comparison to the more usual {25 to 30 wt.%Cr}–containing original alloys. In contrast, their oxidation behaviors are either catastrophic (Co alloy) or acceptable but not really alumina–forming. To improve the oxidation resistance of the Co alloy a version with 10 wt.%Al was additionally elaborated. Increasing the Al content improved significantly the oxidation behavior but also induced obvious modifications in the microstructure, with the appearance of the Co3Al intermetallic replacing almost a half of the volume fraction of the Co solid solution matrix. Except the 5wt.%Al cobalt alloy over which a thick double–structured scale made of CoO and of a mix of CoO and spinel formed, the 5wt.%Al nickel alloy and the 10wt.%Al cobalt alloy were covered a duplex external oxide scale with an outermost spinel oxide and an innermost alumina oxide, rather protective considering the parabolic constants but threatened by spallation even for the rather slow cooling. The responsibility of tantalum, the oxide of which seems deleterious for adherence, was pointed out.