Search Results (51)

This work is devoted to the study of the influence of mechanical activation of aluminum, as well as its modification with graphite on the combustion processes of solid rocket propellant (SRP). Experiments were conducted to determine the ignition induction period, combustion rate and combustion products. Experimental work on ignition and combustion diagnostics was carried out using a diagnostic system at the Institute of Space Propulsion (ISP) of Nanjing University of Science and Technology. A multifunctional combustion diagnostic system was used to characterize the combustion processes of finished SRP samples. A high-speed camera was used to capture the combustion surface regression for various fuels, which can be used to derive their burning rate. The addition of graphite during the mechanochemical activation (MCA) of aluminum significantly affected particle shape and the state of the oxide film, improving the batch homogeneity and increasing the specific surface area. The optimal graphite concentration was approximately 10%, providing additional activation, while 20% graphite caused recoating of the particles and reduced processing efficiency. At constant pressure, it was found that MCA and the introduction of graphite accelerated composite combustion without disrupting stable combustion, with a relatively uniform front. The highest combustion velocity (3.0 mm s⁻¹) was achieved with 10% graphite due to effective heat transfer and catalysis, while increasing its content to 20% reduced the combustion velocity, indicating an optimum of approximately 10%. Full article

This study investigates the biogenic synthesis of copper oxide nanoparticles (CuO NPs) using the aqueous extract of pistachio seed coat as a stabilizing and reducing agent, and a better alternative to the traditional physicochemical approach. The CuO NPs were synthesized by a sustainable approach and characterized using XRD, UV–visible, FTIR, FESEM-EDX, and HRTEM-SAED, and are emphasized for their significance in comprehending how morphology, size, and surface chemistry affect the performance of CuO NPs. The UV–visible spectrophotometry showed an absorption at 273 nm, demonstrating the formation of CuO NPs. SEM and TEM provided a spherical shape with a size range of 50–100 nm. CuO NPs’ antifungal activity was examined against the fungal strains A. niger and P. chrysogenum, and their antibacterial efficacy was evaluated using the agar well disc diffusion method against E. coli and S. aureus. Staphylococcus aureus had the largest inhibitory zone, measuring 18 mm at 100 µg/mL, while Aspergillus niger had the smallest, measuring 8 mm at 25 mg. The IC₅₀ value of the sample was 319.55 ± 3.21 µg/mL. The IC₅₀ value indicates that the CuO NPs exhibit moderate antioxidant potential. The synthesized CuO NPs exhibited excellent catalytic efficiency in the cyclization reaction of chalcones. The findings of the present study highlight CuO NPs synthesis by an eco-friendly, cost-effective and sustainable method from pistachio shell extract. The synthesized CuO NPs demonstrated notable biological and catalytic activity that underscores their future need in various fields such as pharmaceutical, biomedical and industrial catalysis. Full article

Melanin-like polymers, particularly polydopamine, have gained significant attention as photothermal materials due to their broad light absorption (ultraviolet to near-infrared), high photothermal conversion efficiency, negligible fluorescence, good biocompatibility regarding unmodified melanin-like polymers, and universal adhesion. Upon light irradiation, these bioinspired polymers convert absorbed optical energy into heat through molecular vibration and electron–phonon coupling, making them ideal for diverse photothermal applications. This review comprehensively summarizes recent advances in using melanin-like polymers for photothermal purposes. In biomedical engineering, they serve as efficient agents for photothermal therapy and synergistic antibacterial treatment. In catalysis, their photothermal effect enhances pollutant degradation, hydrogen production, and chemical warfare agent detoxification. For water remediation, melanin-like polymers are fabricated into evaporators, membranes, and aerogels for solar-driven steam generation, desalination, and oil spill cleanup. They also enable sensitive photothermal sensing, near-infrared imaging, and laser desorption ionization mass spectrometry imaging. Furthermore, these materials are incorporated into soft actuators and self-healing elastomers for light-controlled shape memory, programmable folding, and remote manipulation. Finally, we discuss remaining challenges such as long-term stability, biocompatibility, scalability, and color limitations and provide future perspectives for advancing melanin-like photothermal materials toward practical applications. Full article

In this study, mullite single-crystal whiskers were prepared by sintering mullite gel powders using HF as a catalyst via the sol–gel process. The effects of the Al₂O₃:SiO₂ molar ratio on the morphology of mullite whiskers in the Al–Si–F system were comprehensively explored during the catalytic reaction. Furthermore, the synergistic effects of the Si:Al ratio and the catalyst content on the growth mechanism of mullite whiskers were evaluated. The morphological characteristics of the whiskers were determined using transmission electron microscopy and scanning electron microscopy. Moreover, morphological parameters, including the diameter and length of whiskers, were statistically analyzed using the Image J software. Additionally, the compositional variation and phase evolution during the whisker growth process were examined via energy-dispersive spectroscopy and X-ray diffraction, respectively, and the corresponding growth mechanism was elucidated. When HF-mediated catalysis reaches a sufficient level (Al₂O₃:SiO₂:HF = 1:1.5:4.3), the low SiO₂ content in the system leads to Al enrichment and the formation of flake-shaped Al₂O₃ structures, indicating an effect analogous to that of increasing catalyst content. Conversely, the simultaneous reduction in the contents of HF and SiO₂ induces different catalytic reactions because of their synergy. Specifically, at relatively low SiO₂ and HF contents, F ions enter the Al–Si–O system via SiF₄, leading to the generation of fluorine-containing topaz, which subsequently transforms into mullite. At relatively high SiO₂ and HF contents, mullite can be directly synthesized via the reaction of AlF3 and SiF₄. With a gradual reduction in the SiO₂ and HF contents, the mullite whiskers exhibit a varying morphology, predominantly transitioning from rod-shaped to flake-shaped and subsequently to rod-shaped structures. This is due to the synergistic effects of the phase transformation and catalytic reactions within the Al–Si–O system. Full article

Leadership lies at the core of public administration, yet research on boundary-spanning leadership has paid limited attention to the micro-level behaviors through which regional collaboration is enacted. Drawing on empirical evidence from China and a mixed-methods research design, this study examines relational leadership behaviors (RLBs) in regional collaborative governance (RCG). It identifies three types of collaborative leaders—leaders embedded in network administrative organizations, leaders within specialized collaborative departments, and leaders exchanged between regions—and four core RLBs: relational initiative, reconciliation, catalysis, and linkage. These behaviors enhance the perceived effectiveness of RCG by fostering trust, managing conflicts, and integrating diverse interests. The findings further show that RLBs are shaped by the collaborative context, including institutional arrangements, leader roles, task complexity, and the temporal dynamics of collaboration. By incorporating relational leadership into a process-oriented perspective, this study extends RCG theory and offers practical insights for improving governance effectiveness in RCG. Full article

Al-rich NH₄-ZSM-5 with highly oriented crystals was directly synthesized through a one-pot hydrothermal technique, using ammonium nitrate as a metal-free mineralizer. The samples were characterized by XRD, N₂ adsorption–desorption, SEM, FTIR, Py-FTIR, ²⁷Al MAS NMR, ²⁹Si MAS NMR, ¹H MAS NMR, and TGA techniques. The impact of aluminum source, ammonium source, and H₂O/SiO₂ molar ratio was studied. XRD results showed that the ZSM-5 catalyst with a low Si/Al ratio (13) was successfully synthesized without any amorphous phase, including a microporous/mesoporous structure. A low H₂O/SiO₂ molar ratio (75) resulted in coffin-shape surface morphology, large b-axis-oriented particles (ca. 19 µm), and high specific surface area (>300 m² g⁻¹), providing a large portion of straight channels (90.5%). The catalytic activity of the catalysts was evaluated in the CO₂ hydrogenation reaction in tandem configuration with a Na/Fe₂O₃ catalyst. The results confirmed that highly b-oriented crystals improved the product shape selectivity to p-xylene by affecting the diffusion resistance. Therefore, the developed catalyst provided high CO₂ conversion (45%) and high aromatic selectivity (77%), with p-xylene accounting for 82% of the produced xylene compounds, over a long-term time on stream (17 h). These results demonstrate the effectiveness of the direct synthesis strategy in producing Al-rich ZSM-5 catalysts with tailored textural and acidic properties for tandem and shape-selective catalysis. Full article

Pulsed liquid-based nanoparticle synthesis has emerged as a versatile and environmentally friendly approach for producing a wide range of nanomaterials with tunable properties. Unlike conventional chemical methods, pulsed techniques—such as pulsed laser ablation in liquids (PLAL), electrical discharge, and other energy-pulsing methods—enable the synthesis of high-purity nanoparticles without the need for toxic precursors or stabilizing agents. This review provides a comprehensive overview of the fundamental mechanisms driving nanoparticle formation under pulsed conditions, including plasma–liquid interactions, cavitation, and shockwave dynamics. We discuss the influence of key synthesis parameters, explore different pulsed energy sources, and highlight the resulting effects on nanoparticle size, shape, and composition. The review also surveys a broad spectrum of material systems and outlines advanced characterization techniques for analyzing synthesized nanostructures. Furthermore, we examine current and emerging applications in biomedicine, catalysis, sensing, energy, and environmental remediation. Finally, we address critical challenges such as scalability, reproducibility, and mechanistic complexity, and propose future directions for advancing the field through hybrid synthesis strategies, real-time diagnostics, and machine learning integration. By bridging mechanistic insights with practical applications, this review aims to guide researchers toward more controlled, sustainable, and innovative nanoparticle synthesis approaches. Full article

Catalysis research is complex and interdisciplinary, involving diverse physical effects and challenging data practices. Research data often captures only selected aspects, such as specific reactants and products, limiting its utility for machine learning and the implementation of FAIR (Findable, Accessible, Interoperable, Reusable) workflows. To improve this, semantic structuring through ontologies is essential. This work extends the established ontologies by refining logical relations and integrating semantic tools such as the Web Ontology Language or the Shape Constraint Language. It incorporates application programming interfaces from chemical databases, such as the Kyoto Encyclopedia of Genes and Genomes and the National Institute of Health’s PubChem database, and builds upon established ontologies. A key innovation lies in automatically decomposing chemical substances through database entries and chemical identifier representations to identify functional groups, enabling more generalized reaction classification. Using new semantic functionality, functional groups are flexibly addressed, improving the classification of reactions such as saponification and ester cleavage with simultaneous oxidation. A graphical interface (GUI) supports user interaction with the knowledge graph, enabling ontological reasoning and querying. This approach demonstrates improved specificity of the newly established ontology over its predecessors and offers a more user-friendly interface for engaging with structured chemical knowledge. Future work will focus on expanding ontology coverage to support a wider range of reactions in catalysis research. Full article

UiO-66-NH₂ is a metal–organic framework (MOF) with open metal sites, making it a promising candidate for adsorption and catalysis. However, the powdery texture of MOFs and the use of toxic solvents during synthesis limit their application. A novel solution to this issue is to create a layered porous composite by encasing the MOF within a flexible and structurally robust aerogel substrate using safe, eco-friendly, and green solvents such as ethanol. The fibrous MOF aerogels, characterized by a desirable macroscopic shape of cylindrical block and hierarchical porosity, were synthesized by two approaches: in situ growth of amine-functionalized UiO-66-NH₂ crystals on a TEMPO-oxidized cellulose nanofiber (TOCNF) and ex situ crosslinking of UiO-66-NH₂ crystals onto a TOCNF network to form UiO-66-NH₂/TOCNF. The incorporation of MOF into the cellulose nanofibrils via the in situ method reduces their aggregation potential, alters the nucleation/growth balance to produce smaller MOF crystals, and enhances mechanical flexibility, as evidenced by SEM images. The three adsorbents, including UiO-66-NH₂, ex situ UiO-66-NH₂/TOCNF, and in situ UiO-66-NH₂/TOCNF, were synthesized and used in this study. The effects of pH, time, temperature, and initial concentration were studied. A maximum adsorption capacity (Qmax) of 549.45 mg/g for Congo Red (CR) and 171.23 mg/g for Orange II (ORII) was observed at pH 6, using 10 mg of in situ UiO-66-NH₂/TOCNF at 40 °C with a contact time of 75 min for CR and 2 h for ORII. The adsorption of both dyes primarily occurs through monolayer chemisorption on the in situ UiO-66-NH₂/TOCNF. The main removal mechanisms were hydrogen bonding and surface complexation. The noteworthy adsorption capacity of in situ UiO-66-NH₂/TOCNF coupled with environment-friendly fabrication techniques indicates its potential applications on a large scale in real wastewater systems. Full article

Heptachlor (HEP) is an insecticide metabolized by cytochrome P450 (CYP) enzymes in the human liver, resulting in the formation of heptachlor epoxide (HEPX). HEPX can persist in the human body for a long duration. Therefore, it can be extremely harmful. A comprehensive understanding of HEP’s metabolic fate may provide a theoretical basis for mitigating associated hazards. However, the specific human CYP isoforms that metabolize HEP, and their metabolic mechanisms, remain unclear. In this study, eight human CYP isoforms were used as catalytic enzymes to investigate the metabolic mechanism of HEP using molecular docking, molecular dynamics simulations, and quantum mechanical calculations. These results indicate that HEP primarily binds to CYP enzymes through hydrophobic interactions, and that the binding positions of HEP are determined by the composition and shape of the hydrophobic pockets near the active site. Based on the reaction distance, CYP2A6, CYP3A4, and CYP3A5 were the only three enzymes that could metabolize HEP. The epoxidation of HEP catalyzed by the doublet state of compound I was effectively concerted, and the rate-determining step was the electrophilic attack of the oxygen atom on HEP. The energy barriers of the rate-determining step vary significantly among different enzymes. A comparison of these energy barriers suggested that CYP3A5 is the most likely enzyme for HEP catalysis in humans. Full article

The remarkable versatility of gold nanoparticles (AuNPs) makes them innovative agents across various fields, including drug delivery, biosensing, catalysis, bioimaging, and vaccine development. This paper provides a detailed review of the important role of AuNPs in drug delivery and therapeutics. We begin by exploring traditional drug delivery systems (DDS), highlighting the role of nanoparticles in revolutionizing drug delivery techniques. We then describe the unique and intriguing properties of AuNPs that make them exceptional for drug delivery. Their shapes, functionalization, drug-loading bonds, targeting mechanisms, release mechanisms, therapeutic effects, and cellular uptake methods are discussed, along with relevant examples from the literature. Lastly, we present the drug delivery applications of AuNPs across various medical domains, including cancer, cardiovascular diseases, ocular diseases, and diabetes, with a focus on in vitro and in vivo cancer research. Full article

Ceria and ceria-based catalysts are very important in redox and acid-base catalysis. Nanoceria have also been found to be important in biomedical applications. To design efficient materials, it is necessary to thoroughly understand the surface chemistry of ceria, and one of the techniques that provides such information about the surface is the vibrational spectroscopy of probe molecules. Although the most commonly used probe is CO, it has some disadvantages when applied to ceria and ceria-based catalysts. CO can easily reduce the material, forming carbonate-like species, and can be disproportionate, thus modifying the surface. Here, we offer a pioneering study of the adsorption of ¹⁵N₂ at 100 K, demonstrating that dinitrogen can be more advantageous than CO when studying ceria-based materials. As an inert gas, N₂ is not able to oxidize or reduce cerium cations and does not form any surface anionic species able to modify the surface. It is infrared and transparent, and thus there is no need to subtract the gas phase spectrum, something that often increases the noise level. Being a weaker base than CO, N₂ has a negligible induction effect. By using stoichiometric nano-shaped ceria samples, we concluded that ¹⁵N₂ can distinguish between surface Ce⁴⁺ sites on different, low index planes; with cations on the {110} facets and on some of the edges, Ce⁴⁺−¹⁵N₂ species with IR bands at 2258–2257 cm⁻¹ are formed. Bridging species, where one of the N atoms from the molecule interacts with two Ce⁴⁺ cations, are formed on the {100} facets (2253–2252 cm⁻¹), while the interaction with the {111} facets is very weak and does not lead to the formation of measurable amounts of complexes. All species are formed by electrostatic interaction and disappear during evacuation at 100 K. In addition, N₂ provides more accurate information than CO on the acidity of the different OH groups because it does not change the binding mode of the hydroxyls. Full article

This study examines the relationship between needle age and rust resistance in Picea crassifolia, focusing on the needle morphology, including size, shape, and physiological traits. One-year-old spruce needles are more susceptible to rust, while two-year-old needles show effective resistance. Using RNA-seq on the Illumina HiSeq500 platform, we analyzed both healthy and diseased one-year-old needles (N and B), as well as healthy one-year-old and two-year-old needles (N and L). We applied a fold change (FC) threshold of ≥2 and a false discovery rate (FDR) of <0.01, alongside GO annotation and KEGG pathway enrichment, to identify differentially expressed genes (DEGs). In N vs. B, DEGs were significantly enriched in processes such as metabolism, cellular function, catalysis, binding, ribosomal function, plant-pathogen interactions, endoplasmic reticulum protein processing, and signal transduction, revealing a polygenic network regulating the rust response. Similarly, in N vs. L, electron microscopy highlighted morphological differences in the wax layers of needles, with subsequent transcriptome sequencing uncovering genes involved in the development of one-year-old and two-year-old needles. DEGs were primarily found in pathways related to cutin, suberin, wax biosynthesis, fatty acid metabolism, photosynthesis, and phenylalanine synthesis. Two-year-old needles displayed reduced stomatal density, higher lignin content, and a thicker wax layer compared to one-year-old needles. Validation of the RNA-seq data through RT-qPCR on 10 DEGs confirmed the consistency of gene expression trends, enhancing our understanding of Picea crassifolia’s genetic response to rust and supporting future research into its disease resistance. Full article

Bismuth sulfide (Bi₂S₃) nanostructures have gained significant attention in the fields of catalysis, optoelectronics, and biomedicine due to their unique physicochemical properties. This paper introduces a simple and cost-effective method for producing Bi₂S₃ microstructures at low temperatures (25 and 70 °C). These microstructures are formed by the hierarchical self-assembly of Bi₂S₃ nanoparticles, which are typically 15–40 nm in size. The nanoparticles are synthesized by the co-precipitation of thioglycolic acid, thioacetamide, and bismuth nitrate in water. The study delves into the phase composition and morphological evolution of the microstructures, concerning the chemical composition of the solution and the synthesis temperature. X-ray analysis has confirmed the formation of single-phase bismuthinite Bi₂S₃. The synthesis process generates primary building blocks in the form of 15–40 nm Bi₂S₃ nanocrystals, which then go through a hierarchical self-assembly process to produce a range of micrometer-sized structures. A scanning electron microscopy examination revealed that the primary nanoparticles self-assemble into quasi-1D worm-like nanostructures, which then self-assemble to create sponge-shaped microstructures. These structures subsequently self-organize and refine into either flower- or dandelion-like microstructures, mostly depending on the synthesis temperature and the chemistry of the digestion medium. Full article

Polyaniline (PANI) constitutes a very propitious conductive polymer utilized in several biomedical, as well as environmental applications, including tissue engineering, catalysis, and photocatalysis, due to its unique properties. In this study, nano-PANI/N-TiO₂ and nano-PANI/Ag-TiO₂ photocatalytic composites were fabricated via aniline’s oxidative polymerization, while the Ag-and N-chemically modified TiO₂ nanopowders were synthesized through the sol–gel approach. All produced materials were fully characterized. Through micro-Raman and FT-IR analysis, the co-existence of PANI and chemically modified TiO₂ particles was confirmed, while via XRD analysis the composites’ average crystallite size was determined as ≈20 nm. The semi-crystal structure of polyaniline exhibits higher photocatalytic efficiency compared to that of other less crystalline forms. The spherical-shaped developed materials are innovative, stable (zeta potential in the range from −26 to −37 mV), and cost-effective, characterized by enhanced photocatalytic efficiency under visible light (energy band gaps ≈ 2 eV), and synthesized with relatively simple methods, with the possibility of recycling and reusing them in potential future applications in industry, in wastewater treatment as well as in biomedicine. Thus, the PANI-encapsulated Ag and N chemically modified TiO₂ nanocomposites exhibit high degradation efficiency towards Rhodamine B dye upon visible-light irradiation, presenting simultaneously high biocompatibility in different normal cell lines. Full article