Search Results (6,941)

The crystallization behavior of poly(aryletherketone) (PAEK) determines its applicable molding process and profoundly affects its mechanical properties. However, research on the crystallization behavior of new PAEKs and their impact on performance is still insufficient. In this work, the isothermal crystallization behavior of a novel PAEK was studied and compared with that of standard poly(etheretherketone) (PEEK). The influence of molding temperatures on the mechanical properties of thermoplastics was revealed by controlling the crystallization temperatures and analyzing the crystallization behavior. The results indicate that due to the disruption of the molecular structure regularity of PAEK, its melting temperature for primary crystallization is generally about 30 °C lower than that of PEEK, which is beneficial for its molding at lower temperatures. At the same undercooling level, the crystallization rate of PAEK is lower than that of PEEK, making it easier to control the crystallinity of PAEK through process parameters. The crystallinity of the thermoplastics increases with the increase in soaking time, thereby improving their tensile strength and modulus. The maximum crystallinity of PAEK is approximately 20.5%, which is lower than PEEK’s value of 31.8%. Therefore, under the same undercooling condition, the tensile strength and modulus of PEEK increase by up to 29.5% and 17.1%, respectively, compared to PAEK. Therefore, by precisely controlling the molding process parameters of PAEK, their crystallization behavior can be managed, enabling the achievement of various properties as needed. Full article

In this study, nanostructured ferberites (FeWO₄) were synthesized via hydrothermal routes in an acidic medium. It was then investigated as an efficient photocatalyst for degrading organic dye molecules, with methylene blue (MB) as a model pollutant. The formation mechanism of ferberite revealed that the physical form of the precursor, FeSO₄·7H₂O, acts as a decisive factor in morphological evolution. Depending on whether it is in a solid or dilute solution form, two distinct nanostructures are produced: nanoplatelets and self-organized microspheres. Both structures are composed of stoichiometric FeWO₄ (Fe: 49%, W: 51%) in a single monoclinic phase (space group P2/c:1) with high purity and crystallinity. The p-type semiconductor behavior was confirmed using Mott–Schottky model and the optical analysis, resulting in small band gap energies (≈1.7 eV) favoring visible absorption light. Photocatalytic tests under simulated solar irradiation revealed rapid and efficient degradation in less than 10 min under near-industrial conditions (pH 5). This was achieved using only a ferberite catalyst and a low concentration of H₂O₂ (4 mM) without additives, dopants, or artificial light sources. Advanced studies based on photocurrent measurements, trapping and stability tests were carried out to identify the main reactive species involved in the photocatalytic process and better understanding of photodegradation mechanisms. These results demonstrate the potential of nanostructured FeWO₄ as a sustainable and effective photocatalyst for water purification applications. Full article

The persistence of the synthetic plastic waste problem makes it one of the most pressing environmental challenges. Sustainable material is an alternative approach to reduce petroleum plastics. In this research, our work aims to convert two biomaterials, water hyacinth (WH) and cassava chip (CC), into value-added biopolymer composite sheets (BCS). The raw materials of both WH and CC were prepared and characterized using physical and chemical treatments. Alkali treatments and chemical modifications were applied to remove lignin, protein, lipid, and other inhibiting components. After that, the two main raw materials of the WH and CC components were varied (100:0, 90:10, 80:20, 70:30, and 60:40, respectively) to investigate the optimal conditions for mixing, blending, and forming processes. Finally, mechanical properties (tensile strength), physical properties (surface morphology using a scanning electron microscope (SEM), crystalline structure by X-ray diffraction (XRD), and water solubility were also evaluated. The results obtained obviously revealed that the BCS reached an optimal ratio of 80:20 and exhibited outstanding properties. We were successful in exploring the potential use of a combination of two kinds of biopolymers under optimal conditions to produce an effective and environmentally friendly BCS in a manner that promotes a sustainable bio-circular economy and zero-waste concepts. Full article

Microwave pretreatment (MWP) has emerged as a promising strategy to enhance the pyrolysis of lignocellulosic biomass due to its rapid, volumetric, and selective heating. By disrupting the recalcitrant structure of cellulose, hemicellulose, and lignin, MWP improves biomass deconstruction, increases carbohydrate accessibility, and enhances yields of bio-oil, syngas, and biochar. When combined with complementary pretreatments—such as alkali, acid, hydrothermal, ultrasonic, or ionic-liquid methods—MWP further reduces activation energies, facilitating more efficient saccharification and thermal conversion. This review systematically evaluates scientific progress in this field through bibliometric analysis, mapping research trends, evolution, and collaborative networks. Key research questions are addressed regarding the technical advantages of MWP, the physicochemical transformations induced in biomass, and associated environmental benefits. Findings indicate that microwave irradiation promotes hemicellulose depolymerization, reduces cellulose crystallinity, and weakens lignin–carbohydrate linkages, which facilitates subsequent thermal decomposition and contributes to improved pyrolysis efficiency and product quality. From an environmental perspective, MWP contributes to energy savings, mitigates greenhouse gas emissions, and supports the integration of renewable electricity in biomass conversion. Full article

Fucoidan B (FucB) is a sulfated polysaccharide with recognized biological activity. In this study, FucB was chemically modified through redox conjugation with gallic acid (GA) to obtain FucB-GA, aiming to enhance its antioxidant properties. Structural characterization using FTIR, NMR, and electrophoresis confirmed the successful covalent binding of GA to FucB without major structural degradation. The conjugation increased the phenolic content and reduced crystallinity, as shown by XRD and SEM, indicating greater amorphous character, which can favor biological applications. Thermogravimetric analysis demonstrated enhanced thermal stability in FucB-GA. Antioxidant activity was evaluated through various in vitro assays. FucB-GA showed superoxide radical scavenging activity of 91.96%, copper chelating capacity of 43.2%, antioxidant capacity of 37 mg AEE/g, and reducing power of 94.22%, significantly higher results than FucB, while no sample chelated iron. Under the conditions analyzed, gallic acid alone showed minimal or no activity in most assays. These results suggest that conjugation with GA increases the antioxidant potential of FucB, while also improving the activity and bioavailability of GA, likely due to the increase in electron-donating and metal-binding groups. Overall, the study supports the development of FucB-GA as a promising antioxidant compound for pharmaceutical or nutraceutical applications. Full article

Background/Objectives: The present work deals with the sol–gel synthesis of hybrid materials based on a silica–polyvinylpyrrolidone (Si-PVP) system. Methods: The nanohybrids have been prepared using an acidic catalyst at ambient temperature. Ibuprofen (IBP) was used as a model substance in the obtained model drug systems, while tetraethyl orthosilicate (TEOS) was used as a silica precursor. Poly(vinylpyrrolidone) (PVP) and IBP were introduced into the reaction mixture as solutions in ethanol using two different approaches: (i) a direct introduction of a drug solution into the reaction mixture during sol–gel synthesis, and (ii) a solvent deposition technique. Results: XRD data provide evidence that IBP entrapped in the silica–PVP network is in an amorphous state. By SEM it was revealed that in the adsorbate, the IBP particles possess an average particle size of about 20 μm. Based on the obtained IR and UV-Vis spectral results, the existence of hydrogen bonding of IBF with silica and PVP could be suggested. Solid-state NMR analysis allowed the identification of the presence of both crystalline-like and amorphous phases in the hybrid material prepared by the sol–gel method, while it was demonstrated that in the adsorbate, the rigid crystalline dimeric structure of the drug has been preserved. Conclusions: The overall analysis of the structural characteristics of the two materials indicated that in the hybrid material obtained by the sol–gel method, the interactions between the amorphous drug, PVP, and the silica matrix are more pronounced as compared to the adsorbate. An improvement of the drug’s aqueous solubility as well of in vitro drug release profile (up to 8 h) was achieved, demonstrating the potential of the developed drug–silica–organic polymer nanohybrid as a promising drug delivery system. Full article

Searching anode materials is an important task for the development of sodium-ion batteries. In this regard, bronze-phase titanium dioxide, TiO₂(B), has been considered as one of the promising materials, owing to its crystal structure with open channels and voids facilitating Na⁺ diffusion and storage. However, the electrochemical de-/sodiation mechanism of TiO₂(B) has not been clearly comprehended, and further experiments are required. Herein, in situ and ex situ observations by a combination of X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, gas chromatography–mass spectrometry was used to provide additional insights into the electrochemical reaction scenario of bronze-phase TiO₂ in Na-ion batteries. The findings reveal that de-/sodiation of TiO₂(B) occurs through a reversible intercalation reaction and without the involvement of the conversion reaction (no metallic titanium is formed and no oxygen is released). At the same time, upon the first Na⁺ uptake process, crystalline TiO₂(B) becomes partially amorphous, but is still driven by the Ti⁴⁺/Ti³⁺ redox couple. Importantly, TiO₂(B) has pseudocapacitive electrochemical behavior during de-/sodiation based on a quantitative analysis of the cyclic voltammetry data. The results obtained in this study complement existing insights into the sodium storage mechanisms of TiO₂(B) and provide useful knowledge for further improving its anode performance for SIBs application. Full article

Mesoporous silica nanoparticles have been synthesized through sol–gel synthesis in basic conditions. Gemini surfactants having urea in the headgroups were used as pore-forming agents. The effect of the spacer length of the surfactant on the particle morphology was studied on the sub-micrometer and nanometer scales using nitrogen porosimetry, small-angle X-ray scattering (SAXS), ultra-small-angle neutron scattering, and scanning and transmission electron microscopy (SEM, TEM). Depending on the spacer, spherical and/or cylindrical nanoparticles formed in different proportions, as revealed by statistical analysis of SEM micrographs. All prepared materials showed the hexagonal pore structure characteristic of the MCM-41 molecular sieves, with the exception of the sample prepared using the gemini surfactant with the shortest spacer length. The influence of the spacer length on the lattice parameter of the pore network, as well as the average size of the ordered domains, has been assessed by SAXS and TEM. Detailed analysis of the TEM images revealed a spread of the lattice parameter in a range of 10–20%. The broadening of the diffraction peaks was shown to be due to the combination of the effects of the finite domain size and the variance of the lattice parameter across the crystalline domains. The structural differences between the silica gels synthesized with the different surfactants were related to the variation of the micelle morphologies, reported in previous light scattering and small-angle scattering experiments. No connection could be revealed between the micelle shape and size and the pore sizes, showing that surfactants with a broad range of spacer lengths can equally well be used for the preparation of MCM-41 materials. Full article

X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) are analytical techniques enabling precise analysis of the electronic structure and local atomic environment in chemical compounds and materials. Their application spans materials science, chemistry, biology, and environmental sciences, supporting studies on catalytic mechanisms, redox processes, and metal speciation. A key advantage of both techniques is element selectivity, allowing the analysis of specific elements without matrix interference. Their high sensitivity to chemical state and coordination enables determination of oxidation states, electronic configuration, and local geometry. These methods are applicable to solids, liquids, and gases without special sample preparation. Modern XAS and XES studies are typically performed using synchrotron radiation, which provides an intense, monochromatic X-ray source and allows advanced in situ and operando experiments. Sub-techniques such as XANES (X-ray absorption near-edge structure), EXAFS (Extended X-ray Absorption Fine Structure), and RIXS (resonant inelastic X-ray scattering) offer enhanced insights into oxidation states, local structure, and electronic excitations. Despite their broad scientific use, applications in pharmaceutical research remain limited. Nevertheless, recent studies highlight their potential in analyzing crystalline active pharmaceutical ingredients (APIs), drug–biomolecule interactions, and differences in drug activity. This review introduces the fundamental aspects of XAS and XES, with an emphasis on practical considerations for pharmaceutical applications, including experimental design and basic spectral interpretation. Full article

Polyethylene terephthalate (PET) films were modified by direct fluorination using fluorine gas at room temperature and 660 torr for reaction times ranging from 10 min to 5 h. Some of the fluorinated samples were dried at 70 °C for 7 days. FT-IR and XPS analyses confirmed the successful incorporation of fluorine into the PET structure, with the formation of -CHF- and -CF₂- groups. The degree of fluorination increased with the reaction time, but excessive reaction led to the formation and loss of CF₄. Drying further decreased the fluorine content due to the continued CF₄ formation. XRD revealed that fluorination increased the crystallinity of PET owing to increased polarity, whereas drying decreased the crystallinity owing to increased crosslinking. The DSC results showed an increase in the glass transition temperature (T_g) after fluorination and drying, which was attributed to increased polarity and crosslinking, respectively. The surface hydrophilicity of PET increased significantly with fluorination time, and the water contact angle decreased to as low as 3.35°. This was due to the introduction of polar fluorine atoms and the development of a rough and porous surface morphology, as observed by AFM. Interestingly, drying of the fluorinated samples led to an increase in the water contact angle, with a maximum of 85.95°, owing to increased crosslinking and particle formation on the surface. This study demonstrates a simple and effective method for controlling the hydrophilicity and hydrophobicity of PET surfaces via direct fluorination and drying. Full article

The use of molybdenum-based alloys as materials for components operating under high temperatures and significant mechanical loads is widely recognized due to their excellent mechanical properties. However, their low high-temperature resistance remains a critical limitation, which can be effectively mitigated by applying protective coatings. In this study, we investigate the influence of a two-step coating process on the properties and performance of the TZM molybdenum alloy. In the first step, pack cementation was performed. Simultaneous surface saturation with aluminum and silicon, a process known as aluminosiliconizing, was conducted at 1000 °C for 6 h. The saturating mixture comprised powders of aluminum, silicon, aluminum oxide, and ammonium chloride. The second step involved the application of a pre-ceramic coating based on polyhydrosiloxane modified with silicon and boron. This treatment effectively eliminated pores and cracks within the coating. Thermodynamic calculations were carried out to evaluate the likelihood of aluminizing and siliconizing reactions under the applied conditions. Aluminosiliconizing of the TZM alloy resulted in the formation of a protective layer 20–30 µm thick. The multiphase structure of this layer included intermetallics (Al₆₃Mo₃₇, MoAl₃), nitrides (Mo₂N, AlN, Si₃N₄), oxide (Al₂O₃), and a solid solution α-Mo(Al). Subsequent treatment with silicon- and boron-modified polyhydrosiloxane led to the development of a thicker surface layer, 130–160 µm in thickness, composed of crystalline Si, amorphous SiO₂, and likely amorphous boron. A transitional oxide layer ((Al,Si)₂O₃) 5–7 µm thick was also observed. The resulting coating demonstrated excellent structural integrity and chemical inertness in an argon atmosphere at temperatures up to 1100 °C. High-temperature stability at 800 °C was observed for both coating types: aluminosiliconizing, and aluminosiliconizing followed by the pre-ceramic coating. Moreover, additional oxide layers of SiO₂ and B₂O₃ formed on the two-step coated TZM alloy during heating at 800 °C for 24 h. These layers acted as an effective barrier, preventing the evaporation of the substrate material. Full article

In response to the increasing demand for environmentally friendly and cost-effective adsorbents in wastewater treatment, this study reports the green synthesis, characterization, and application of a magnetic epichlorohydrin Rosa canina (m-ECH-RC) nanocomposite for removing Safranin O (SO), a commonly used cationic dye in textile effluents. The synthesized material was characterized using Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and zeta potential analyses to reveal its surface morphology, pore structure, functional groups, crystallinity, and colloidal stability. Adsorption performance was systematically tested under various conditions, including pH, adsorbent dose, contact time, ionic strength, and initial dye concentration. Kinetic analyses revealed that the adsorption process of Safranin O dye mainly obeys pseudo-second-order kinetics, but intraparticle and film diffusion also contribute to the process. As a result of the Isotherm analysis, it was found that the adsorption process conformed to the Langmuir model. Testing on real textile wastewater samples demonstrated a removal efficiency of 75.09% under optimized conditions. Reusability experiments further revealed that the material maintained high adsorption–desorption performance for up to five cycles, emphasizing its potential for practical use. These findings suggest that m-ECH-RC is a viable and sustainable adsorbent for treating dye-laden industrial effluents. Full article

Chitin deacetylases (CDAs), which catalyze the deacetylation of chitin to produce chitosan, have garnered significant interest due to their environmental compatibility and ability to control product quality. However, the low conversion efficiency resulting from chitin’s high molecular weight and crystallinity, as well as structural limitations of CDAs, has impeded their industrial application. In this study, we present the integrated approach combining bioinformatics and computational tools (adaptive Poisson–Boltzmann solver, Fpocket, and ProteinPlus) to systematically analyze sequence features and variations in active pocket properties among CDAs from diverse origins. Experimental evaluation of the deacetylation activity of AnCDA, AsCDA, BaCDA, and ScCDA, each with distinct pocket characteristics, on chitin substrates with varying molecular parameters revealed that CDAs with high hydrophobicity scores and low surface-to-volume ratios exhibited superior efficiency in converting high-molecular-weight chitin. These findings guide the rational selection and engineering of CDAs for industrial biocatalysis. Full article

The crystallization behavior of polymers affects the structure of aggregated states, which influences the properties of materials. Atomic force microscopy (AFM) is a helpful characterization tool with high spatial resolution at the nanometer-to-micrometer scale and low-destruction imaging capabilities, making it an important means of studying polymer crystallography. This review is intended for scientists in polymer materials and physics, aiming to inspire how the rich applications of AFM can be harnessed to address fundamental scientific questions in polymer crystallization. This paper reviews recent advances in polymer crystallization characterization based on AFM, focusing on its applications in visualizing hierarchical polymer crystal structures (single crystals, spherulites, dendritic crystals, and shish kebab crystals), investigating crystallization kinetics (in situ monitoring of crystal growth), and analyzing structure–property relationships (structural changes under temperature and stress). Finally, we introduce the application of the latest AFM technology in addressing key issues in polymer crystallization, such as single-molecule force spectroscopy (SMFS) and atomic force microscopy–infrared spectroscopy (AFM-IR). As AFM technology advances toward higher precision, greater efficiency, and increased functionality, it is expected to deliver more exciting developments in the field of polymer crystallization. Full article

This study investigates iron acetylacetonate (Fe(acac)₃) as a catalyst for enhancing high-temperature oxidation (HTO) during in situ combustion (ISC) of heavy oil. Thermal analysis revealed that Fe(acac)₃ decomposes at 360 °C to form crystalline magnetite (Fe₃O₄). This transformation precedes the HTO regime. Differential scanning calorimetry demonstrated significantly intensified HTO reactions in catalytic systems, as peak temperatures were lower than those in non-catalytic reactions. Kinetic analysis showed that the catalyst reduces HTO activation energy by 15.6%, substantially increasing reaction rates across the HTO temperature range. X-ray powder diffraction confirmed that the mixed-valence Fe²⁺/Fe³⁺ configuration in the magnetite structure facilitates electron transfer during oxidation, enabling more complete combustion at lower temperatures. These findings represent a novel approach to catalyst design, from general activity to temperature-specific activation for a more stable and efficient in situ combustion process. Full article