Search Results (15,108)

This study examines the high-temperature degradation of Hastelloy C276, a corrosion-resistant nickel-based alloy, during exposure to combustion products generated by methane and 99% cracked ammonia. Using a high-pressure optical combustor (HPOC) at 4 bar and exhaust temperatures of 815–860 °C, standard tensile specimens were exposed for five hours to fully developed post-flame exhaust gases, simulating real industrial turbine or burner conditions. The surfaces and subsurface regions of the samples were analysed using scanning electron microscopy (SEM; Zeiss Sigma HD FEG-SEM, Carl Zeiss, Oberkochen, Germany) and energy-dispersive X-ray spectroscopy (EDX; Oxford Instruments X-MaxN detectors, Oxford Instruments, Abingdon, United Kingdom), while mechanical properties were evaluated by tensile testing, and the gas-phase compositions were tracked in detail for each fuel blend. Results show that exposure to methane causes moderate oxidation and some grain boundary carburisation, with localised carbon enrichment detected by high-resolution EDX mapping. In contrast, 99% cracked ammonia resulted in much more aggressive selective oxidation, as evidenced by extensive surface roughening, significant chromium depletion, and higher oxygen incorporation, correlating with increased NO_x in the exhaust gas. Tensile testing reveals that methane exposure causes severe embrittlement (yield strength +41%, elongation −53%) through grain boundary carbide precipitation, while cracked ammonia exposure results in moderate degradation (yield strength +4%, elongation −24%) with fully preserved ultimate tensile strength (870 MPa), despite more aggressive surface oxidation. These counterintuitive findings demonstrate that grain boundary integrity is more critical than surface condition for mechanical reliability. These findings underscore the importance of evaluating material compatibility in low-carbon and hydrogen/ammonia-fuelled combustion systems and establish critical microstructural benchmarks for the anticipated mechanical testing in future work. Full article

The characterization of environmental Pseudomonas spp. from pharmaceutical industries is a relatively underexplored area of research. This study used 40 isolates of Pseudomonas from a pharmaceutical company that had been presumptively identified as Pseudomonas aeruginosa by VITEK^®2. The isolates were characterized using 16S rRNA sequencing, Multilocus Sequence Typing (MLST), Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass (MALDI–TOF MS), Fourier Transform Infrared (FT-IR) spectroscopy, ERIC-PCR, antimicrobial susceptibility profiling, and biofilm formation assessment on stainless steel surfaces. Twenty isolates were confirmed as P. aeruginosa. Sixteen isolates were only identified to the genus level of Pseudomonas, and the remaining four isolates were identified as Enterococcus faecalis (n = 2), Proteus spp. (n = 1), and Staphylococcus saprophyticus subsp. bovis/S. edaphicus/S. saprophyticus subsp. saprophyticus/S. pseudoxylosus/S. xylosus/S. caeli/S. ureilyticus. Typing of the 20 P. aeruginosa strains yielded 18 distinct FT-IR profiles and 19 ERIC-PCR profiles. The MLST analysis identified eight new sequence types (ST4292–ST4299). All strains were classified as multidrug-resistant (MDR), exhibiting resistance to multiple antimicrobial classes. Biofilm formation was observed in 28 (77.8%) Pseudomonas spp. strains on polystyrene surfaces, classified as moderately or strongly adherent, while all P. aeruginosa strains formed biofilms on stainless steel. Of the three disinfectants tested, sodium hypochlorite at 0.01% showed the best performance, reducing or eliminating biofilm formation in 24 (85.7%) strains. The regular evaluation of disinfection effectiveness in pharmaceutical industries is essential, as the presence of biofilm-forming strains can compromise production and contaminate final products. Full article

This work addresses the influence of Ni on the natural passivation process of stainless steels (SSs) in alkaline media simulating concrete pore solution by a combination of electrochemical and X-ray photoelectron spectroscopy (XPS) surface analysis. It was found that the involvement of Ni in the passive film on the SS promoted Fe depletion at the passive film/substrate interface and increased the content of Cr oxide during natural passivation, thereby enhancing the corrosion resistance of the passive film. The passive film with Ni has a higher breakdown potential and can be more easily re-passivated compared with a passive film without Ni. Full article

In this work, a multifunctional surface engineering strategy was developed to impart both flame-retardant and hydrophobic properties to cotton fabrics. In the first stage, cellulose fibers were modified with poly(methylvinyl)siloxane containing trimethoxysilyl groups, 2,4,6,8-tetramethyl-divinyl-bis(trimethoxysilylpropyltioethyl)cyclotetrasiloxane, or tetrakis(vinyldimethylsiloxy)tetrakis(trimethoxysilylpropyltioethyl)octasilsesquioxane (POSS). All modifiers contained alkoxysilyl groups capable of forming covalent bonds with cellulose hydroxyl groups. The modification was performed using a dip-coating process followed by thermal curing. This procedure enabled the formation of Si-O-C linkages and the generation of a reactive organosilicon layer on the cotton surface. In the second step, O,O′-diethyl dithiophosphate was grafted directly onto the vinyl-functionalized fabrics via a thiol-ene click reaction. This process resulted in the formation of a phosphorus- and sulfur-containing protective layer anchored within the siloxane-based network. The obtained hybrid coatings were characterized using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and SEM-EDS. These analyses confirmed the presence and uniform distribution of the modifiers on the fiber surface. Microscale combustion calorimetry demonstrated a substantial reduction in the heat release rate. Thermogravimetric analysis (TG/DTG) revealed increased char formation and altered thermal degradation pathways. The limiting oxygen index (LOI) increased for all modified fabrics, confirming enhanced flame resistance. Water contact angle measurements showed values above 130°, indicating effective hydrophobicity. As a result, multifunctional textile surfaces were obtained. In addition, the modified fabrics exhibited partial durability toward laundering and retained measurable flame-retardant and hydrophobic performance after repeated washing cycles. Full article

In this study, ZnO–GO nanocomposites were synthesized from waste Zn–C batteries and used for the photocatalytic degradation of malachite green (MG) under UV light. ZnO–GO nanocomposites with different GO contents (1, 2.5, and 5 wt%) were prepared at room temperature and characterized by XRD, SEM, EDS, and UV–Vis spectroscopy. The GO content significantly affects the morphology, optical properties, and photocatalytic activity of the nanocomposites. In the presence of ZnO NPs, a malachite green degradation efficiency of 96.25% was achieved in 90 min, while ZnO–1%GO, ZnO–2.5%GO, and ZnO–5%GO achieved 95.35%, 97.27%, and 99.6% MG degradation, respectively, in just 30 min. The photocatalytic degradation process of MG was optimized using Response Surface Methodology (RSM). The effects of GO content, catalyst dosage, initial MG concentration, and irradiation time on the efficiency of photocatalytic degradation were investigated, and optimal conditions were determined. Under optimal conditions, a photocatalytic degradation efficiency of 98.51% was achieved. These results indicate that ZnO–GO nanocomposites synthesized from waste Zn–C batteries are efficient and environmentally friendly photocatalysts for the treatment of dye-contaminated wastewater. Full article

Carbon-reinforced epoxy laminated composite (CREC) structures are increasingly utilized in high-speed marine vehicles (HSMVs) due to their high specific strength and stiffness; however, they are frequently subjected to impact loads like slamming and aggressive environmental agents during operation. This study experimentally investigates the Compression After Impact (CAI) behavior of CREC plates with varying lamination sequences under both atmospheric and accelerated aging conditions. The samples were produced using the vacuum-assisted resin infusion method with three specific orientation types: quasi-isotropic, cross-ply, and angle-ply. To simulate the marine environment, specimens were subjected to accelerated aging in a salt fog and cyclic corrosion cabin for periods of 2, 4, and 6 weeks. Before and following the aging process, low-velocity impact tests were conducted at an energy level of 30 J, after which the residual compressive strength was measured by CAI tests. At the end of the aging process, after the sixth week, the performance of plates with different layer configuration characteristics can be summarized as follows: Plates 1 and 2, which are quasi-isotropic, exhibit opposite behavior. Plate 1, with an initial toughness of 23,000 mJ, increases its performance to 27,000 mJ as it ages, while these values are around 27,000 and 17,000 mJ, respectively, for Plate 2. It is thought that the difference in configurations creates this difference, and the presence of the 0° layer under the effect of compression load at the beginning and end of the configuration has a performance-enhancing effect. In Plates 3 and 4, which have a cross-ply configuration, almost the same performance is observed; the performance, which is initially 13,000 mJ, increases to around 23,000 mJ with the effect of aging. Among the options, angle-ply Plates 5 and 6 demonstrate the highest performance with values around 35,000 mJ, along with an undefined aging effect. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analyses confirmed the presence of matrix cracking, fiber breakage, and salt accumulation (Na and Ca compounds) on the aged surfaces. The study concludes that the impact of environmental aging on CRECs is not uniformly negative; while it degrades certain configurations, it can enhance the toughness and energy absorption of brittle, cross-ply structures through matrix plasticization. Full article

The aim of this study was to investigate the effects of three lipopolysaccharides (LPS), obtained from Hafnia alvei PCM 1200, Proteus penneri 12, and Proteus vulgaris 9/57, on the fluidity of liposomal lipid membranes. The experiments were performed on liposomes composed of egg yolk lecithin (EYL) in the liquid-crystalline phase and synthetic lecithin (DPPC) in the gel phase. The experimental results were compared with data obtained from a computational model of the membrane surface layer. Membrane fluidity was assessed using EPR spectroscopy with the spin probes TEMPO (surface layer; changes in the F parameter) and 16-DOXYL (hydrophobic core; changes in the τ parameter). In EYL liposomes, all LPS samples induced a reduction in surface-layer fluidity (decrease in the F/F₀ ratio). In contrast, effects on the hydrophobic core (τ/τ₀) were observed only at low dopant concentrations (<0.2%), above which membrane fluidity plateaued. In DPPC membranes, the response was more complex: local minima in F/F₀ and maxima in τ/τ₀ were detected, indicating transient alterations in membrane stiffening and plasticization that depended on the specific LPS applied. Computational simulations of the membrane surface further confirmed the greater susceptibility of low-mobility systems (corresponding to the gel phase) to dopant-induced perturbations. In the model, the best agreement with the EPR data was obtained when an effective dopant charge of q = 3 was assumed. Full article

Polylactic acid (PLA) films were directly fluorinated using fluorine gas at room temperature under varying conditions: fluorine concentrations of 190–760 Torr and reaction times of 10–60 min. Some of the fluorinated samples were subsequently dried at 70 °C for 2 d. Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses verified the successful introduction of fluorine and the formation of -CF_x and C=OF groups on the PLA surface after fluorination. The fluorination level initially increased with increasing reaction time or fluorine concentration but then decreased because of the formation and escape of CF₄ gasification. Drying further reduced the surface fluorine content. Both fluorination and drying increased the glass transition temperature of PLA, which was attributed to the increase in surface polarity and crosslinking density of the polymer. Fluorination significantly improved the surface hydrophilicity of PLA, with the water contact angle decreasing from 64.09°to 18.75°. This was due to the formation of a rough, porous surface caused by the introduction of polar fluorine atoms, as observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). However, drying the fluorinated samples increased the water contact angle to 91.46°, resulting in hydrophobicity owing to increased surface crosslinking. This study demonstrates a simple and effective method for tuning the hydrophilic–hydrophobic properties of PLA surfaces using direct fluorination and thermal treatment. Full article

This study addresses the issues of poor stability and difficulty in recovery of free horseradish peroxidase (HRP) by developing a multi-level composite immobilized carrier that combines high loading capacity with long-term stability. The SiO₂@MnO₂@MAF-7 core–shell structured carrier was prepared via a solvothermal self-assembly method. Three immobilization strategies—adsorption, covalent cross-linking, and encapsulation—were systematically compared for their immobilization efficacy on HRP. The material structure was analyzed using techniques such as specific surface area analysis (BET), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) to characterize the material structure. Enzyme kinetic parameter determination experiments were conducted to systematically evaluate the performance advantages of the immobilized enzyme. BET analysis showed that SiO₂@MnO₂@MAF-7 had a specific surface area of 251.99 m²/g and a mesoporous area of 12.47 nm, and its HRP loading was 50.37 U/mg (immobilization efficiency 85.03%). Compared with free HRP, the Km value of the immobilized enzyme was decreased by 42%, the activity retention rate was increased by 35–50% at 80 °C and pH 4–9, and the activity was maintained by 65% after five repeated uses. In this study, MAF-7 was combined with MnO₂/SiO₂ for HRP immobilization for the first time, and the triple effect of rigid support-catalytic synergy-confined protection synergistically improved the stability of the enzyme, providing a new strategy for the industrial application of oxidoreductases. Full article

A composite based on θ-Al₂O₃ microspheres coated with graphene oxide (GO) and reduced graphene oxide (RGO) was prepared and evaluated as a sorbent for the removal of synthetic dyes from aqueous solutions. GO was synthesized by a modified Hummers’ method and deposited onto alumina microspheres via ultrasound-assisted treatment under various conditions, followed by supercritical reduction to obtain the Al₂O₃_RGO composite. The structure, morphology, and composition of the materials were characterized by Raman spectroscopy, SEM, TGA/DSC, FTIR, and XRD, revealing the formation of mono- and few-layer GO/RGO coatings on the substrate surface. Adsorption tests for cationic methylene blue (MB) dye and anionic methyl orange (MO) dye demonstrated that the alumina substrate was inactive, whereas GO- and RGO-coated microspheres exhibited high adsorption efficiency for MB and partial uptake of MO from water solutions. In mixed-dye solutions, both Al₂O₃_GO and Al₂O₃_RGO composites showed selectivity toward MB, and the RGO-based composite demonstrated enhanced MB adsorption at low concentrations. The results highlight GO/RGO-coated θ-Al₂O₃ microspheres as convenient and selective composite sorbents for water purification processes. Full article

Continuous excessive CO₂ emissions have a negative impact on the environment. In order to address the issue of CO₂ emission control, its conversion to some valuable commodities is the way forward in dealing with this issue. Additionally, the conversion of CO₂ to some valuable product such as methanol fuel will not only tackle the issue but also result in producing energy. Here, the co-precipitation method was used to synthesize Cu-ZnO bimetallic catalysts based on TiO₂ support to be applied for CO₂ conversion to methanol fuel. To elucidate the role of potassium (K) as a promoter, varied concentrations of K were added to parent Cu-ZnO/TiO₂ catalysts. A number of analytical techniques were used to scrutinize the physico-chemical properties of calcined Cu-ZnO/TiO₂ catalysts. The crystalline nature of TiO₂ catalyst support with high metal oxide dispersion were the major findings disclosed based on X-ray diffraction examinations. The combination of the mesoporous and microporous character of the K-promoted Cu-ZnO/TiO₂ catalysts was discovered using the N₂ adsorption–desorption technique. Similarly, N₂ adsorption–desorption studies also revealed surface defects by K-promotion. The creation of surface defects was also endorsed by X-ray photoelectron spectroscopy (XPS) by showing additional XPS peaks for O1s in higher binding energy (BE) regions. XPS also showed the oxidation states of K-promoted Cu-ZnO/TiO₂ catalysts as well as metal–support interactions. Activity results demonstrated the active profile of K-promoted Cu-ZnO/TiO₂ catalysts for methanol synthesis via CO₂ reduction in a liquid phase slurry reactor. The methanol synthesis rate was accelerated from 35 to 53 g.MeOH/kg.cat.h by incorporating of K to parent Cu-ZnO/TiO₂ catalysts at reaction temperature and pressure of 210 °C and 30 bar, respectively. Structure–activity investigations revealed a promoting role of K by facilitating Cu reduction as well metal–support interaction. The comparative study further revealed the importance of K promotion for the title reaction. Full article

Background: Liposomes have been successfully used in clinics as an excellent drug delivery system. However, once they enter the body, they adsorb surrounding proteins and form a protein corona, which affects how liposomes behave in vivo. Therefore, controlling the formation of the protein corona is crucial for achieving effective treatment outcomes. Among the many variables affecting liposome protein corona formation, the composition of the liposomes themselves and the surrounding ionic environment are two particularly critical factors. Methods: In this context, this study selected bovine serum albumin as a model protein to investigate the influence and mechanism of physiologically relevant inorganic ions (magnesium chloride) and varying proportions of cationic lipid components (1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)) on protein adsorption behavior of liposomes. We evaluated characterization parameters, including particle size and zeta potential, and employed various spectroscopic techniques to elucidate the changes during the interaction between bovine serum albumin and liposomes. Results: The zeta potential results showed that liposomes without DOTAP exhibited a significantly negative potential (−45.20 ± 0.24 mV), while the zeta potential became increasingly positive with higher DOTAP proportions (+19.64 ± 0.39 mV and +51.03 ± 1.74 mV). Correspondingly, the amount of protein adsorption also increased with the rising DOTAP content. Furthermore, fluorescence spectroscopy indicated that the addition of either DOTAP or magnesium ions led to a decrease in both the K_sv and K_a parameters. Conclusions: Specific hypothetical models were advanced subsequently; per the varying proportion of DOTAP, we proposed an insertion or surface adsorption model, and further examined the influence of magnesium chloride on the interactions between the liposomes and proteins. We believe this study will provide a new research paradigm for the design and application of liposomes, laying a foundation for further in vivo investigations. Full article

Metal nanoparticles (NP) are increasingly used in biomedical applications. Among them, silver NPs (AgNPs) are used as active components in antibacterial coatings for wound dressings, medical devices, implants, cosmetics, textiles, and food packaging. On the other hand, AgNPs can be toxic to humans, depending on the dose and route of exposure, as agents delivering silver to cells. The cysteine residues are the primary molecular targets in such exposures, due to the high affinity of Ag⁺ ions to thiol groups. The Endothelial monocyte-activating polypeptide II (EMAP II), a cleaved C-terminal peptide of the intracellular aminoacyl-tRNA synthetase multifunctional protein AIMP1, contains five cysteines exposed at its surface. This prompted the question of whether they can be targeted by Ag⁺ ions present at the AgNPs surface or released from AgNPs in the course of oxidative metabolism of the cell. We explored the interactions between recombinant EMAP II, tRNA, and AgNPs using UV-Vis and fluorescence spectroscopy, providing insight into the effects of AgNPs dissolution kinetics on interaction EMAP II with tRNA. In addition, the EMAP II fragments binding to intact AgNPs were established by heteronuclear ¹H-¹⁵N HSQC spectra utilizing a paramagnetic probe. Structural analysis of the EMAP II reveal that the 3D structure of protein was destabilized (partially denatured) by the binding of Ag⁺ ions released from AgNPs at the most exposed cysteines. Surprisingly, this effect enhanced tRNA affinity to EMAP II, lowering its $K_d$. The course of the EMAP II/tRNA/AgNP reaction was also modulated by other factors, such as the presence of Mg²⁺ ions and TCEP, a thiol-group protector used to mimic the reducing conditions of the cell. Full article

To reduce CO₂ emissions into the environment, the automotive sector uses microalloyed structural steels coated with electrophoretic paint in various components, such as the chassis, to reduce weight and increase corrosion resistance. AHSSs are coated with electrophoretic paint (E-coat). Still, to improve adhesion, they undergo a pretreatment, such as zinc phosphate or zirconium oxide. This research will analyze the effects and behavior of these coatings during corrosion on a complex-phase (CP) 780 AHSS using different electrochemical techniques, including cyclic potentiodynamic polarization (CPP), electrochemical noise (EN), and electrochemical impedance spectroscopy (EIS). The CP 780 AHSS was immersed in a 3.5 wt. % sodium chloride solution. Results show that AHSS CP 780 presented a mixed corrosion mechanism due to the heterogeneity of the surface of the zinc phosphate and zirconium oxide pretreatments. On the other hand, the samples with an E-coat paint coating and pretreatment (Zn₃(PO₄)₂/E-coat and ZrO₂/E-coat) have the lowest current densities with values of 6.44 × 10⁻¹¹ 1.02 × 10⁻⁹ A/cm² and also do not show a tendency towards localized corrosion or negative hysteresis. Full article

In this paper, a new polymeric membrane including polymers (cellulose acetate, polyethylene glycol 400), copolymer poly(4-vinylpyridine)-block-polystyrene, and TiO₂ nanoparticles were synthesized by the phase inversion method. In order to investigate the presence and the influence of the TiO₂ nanoparticles on the membrane matrix, a polymeric membrane without TiO₂ nanoparticles was prepared by the same preparation method. The structure of the polymeric membranes was characterized by several techniques, such as Fourier transform infrared spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and impedance spectroscopy. Also, the water contact angle, water retention, and porosity were determined. The results showed that the TiO₂ nanoparticles were incorporated into the pores and onto the surface of the polymeric membrane, which resulted in a more uniform structure. In addition, these polymeric membranes were tested for the removal of cadmium ions from synthetic waste-water using a laboratory-scale electrochemical separation system with a custom-built setup. The results showed that the polymeric membrane with TiO₂ nanoparticles showed a high cadmium ions removal rate (95.53%), compared to the polymeric membrane without TiO₂ nanoparticles (85.29%), after a 1.5 h electrochemical separation test. The final results indicated that the polymeric membranes prepared with TiO₂ nanoparticles had excellent thermal stability and exhibited the best ionic conductivity. The electrochemical separation system proved that the obtained polymeric membranes effectively remove cadmium from the synthetic waste-water. Full article