This study focuses on the solid phase extraction of biogenic amines (BAs) using a sol-gel adsorbent immobilized with a hydrazone ligand, named 2-hydroxy-5-nitrobenzaldehyde-2,4-dinitrophenylhydrazone. The hydrazone compound was synthesized and characterized through Fourier Transform Infrared Spectroscopy (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The efficiency of the sorbent material for extracting BAs was evaluated using the solid phase extraction (SPE) method. Key experimental parameters affecting BA extraction, including pH, equilibrium time, ligand concentration, and biogenic amine (BA) concentration, were systematically investigated. The results indicated a strong recovery of BAs from aqueous samples, demonstrating a significant affinity between the sol-gel matrix containing the hydrazone ligand and the target analytes. The findings demonstrate that incorporating the hydrazone ligand resulted in a marked enhancement of extraction efficiency at a concentation of 17 & times; 10(-3) M. Notably, the method exhibited high selectivity for aliphatic biogenic amines such as putrescine (PUT), cadaverine (CAD), and spermidine (SPD). This extraction method was successfully applied to food samples, yielding good recovery rates.
The development of aluminum-based cladding materials for nuclear fuel confinement is advancing in line with the increasing demand for high-density fuels. Alloying aluminum with magnesium (Mg), iron (Fe), and nickel (Ni) is expected to improve mechanical strength and thermal stability, thereby compensating for the higher hardness associated with high-density fuels. Heat treatment is a proven strategy to further enhance the performance of Al-based alloys in nuclear applications. In this study, Al-Mg-Fe-Ni alloys were fabricated by arc melting, homogenized, rolled, and subjected to heat treatment at 500 degrees C for 1.5, 3, and 4.5 h. Structural analysis using XRD and GSAS confirmed the formation of a substitutional solid solution with partial preferred orientation. Heat treatment decreased hardness due to recovery and partial recrystallization, but increased bulk density. The sample treated for 1.5 h exhibited the best balance, with a hardness of 82.81 +/- 0.06 HV and a density of 2.7232 +/- 0.0002 g/cm(3). These results demonstrate that controlled thermal treatment can be used to optimize the structure-property relationship of Al-based alloys, offering valuable insights for the design of advanced cladding materials for high-density nuclear fuels.
Co-creation has increasingly gained traction as a means to search for innovative solutions to wicked problems, including in the pursuit of the green transition. Whereas several contributions on the forms, determinants and successful outcomes of co-creation for the green transition focus on the Global North, experiences from the Global South – where non-state actors often drive local green co-creation – are increasingly drawing attention. The extant literature seems to suggest that state actors play different roles in different countries and regions, with a directive leadership role being more pronounced in the Global North than in the Global South. To explore the role(s) government actors play in the orchestration of local green co-creation in the Global South, we rely on a multiple case study drawing on the GOGREEN project database, examining the governance factors that shape the co-creation of green transitions through the study of 36 case studies across 28 countries. Relevant case studies from the Global South suggest two possible roles that government actors may play: (i) governments welcome local co-creation processes ‘out of opportunity’, exploiting opportunities for co-creation where non-state actors mobilize local resources and government has limited capacity; and (ii) governments support local green co-creation ‘out of necessity’ in contexts where non-state actors initiate such processes in response to pressing needs despite initial reluctance by government actors due to various reasons.
Dihydropyrimidinones (DHPMs) are heterocyclic compounds with various biological activities. These biological activities are important for pharmacological applications. DHPMs are commonly synthesized via the Biginelli reaction, which requires an efficient and recyclable catalyst to achieve high yields under optimized reaction conditions. Homogeneous catalysts have been widely used in the Biginelli reaction because of their high catalytic activity. However, their difficult separation from the reaction mixture and limited reusability have driven the development of heterogeneous catalysts with improved recovery and recycling performance. Previous studies on heterogeneous catalysts have reported several limitations, such as high catalyst loading, prolonged reaction times, reduced activity upon reuse, and complicated recovery procedures. As a result, this study aims to prepare CuO/Fe 3 O 4 /GO and NiO/Fe 3 O 4 /GO magnetic heterogeneous catalysts for the synthesis of a target DHPM compound. The catalysts were prepared through stepwise surface modification of Fe 3 O 4 , followed by the addition of graphene oxide, CuO, and NiO. Structural characterization confirmed the successful formation of the composites. Catalytic evaluation showed that CuO/Fe 3 O 4 /GO produced the highest yield of the target DHPM compound (85%) under optimized reaction conditions (10 wt% catalyst, 80 °C), whereas NiO/Fe 3 O 4 /GO produced a 50% yield under the same conditions. Raman analysis indicated a small difference in the degree of structural disorder between CuO/Fe 3 O 4 /GO and NiO/Fe 3 O 4 /GO. In addition, CuO/Fe 3 O 4 /GO exhibited a smaller average particle size, which may contribute to its higher catalytic performance. Furthermore, the CuO/Fe 3 O 4 /GO catalyst remained active after five reaction cycles, with a yield of 81%. These findings indicate that CuO/Fe 3 O 4 /GO is a promising reusable magnetic heterogeneous catalyst for DHPM synthesis.
A TiO2/PrCrO3nanocomposite was synthesized using an eco-friendly approach in which Acalypha wilkesiana leaf extract served as a natural mediator. The photocatalytic performance of the prepared material was evaluated under visible light irradiation using Malachite Green (MG) as a model dye pollutant. Structural characterization confirmed the presence of TiO2, PrCrO3 phases and the composite on a nanoscale. Optical studies revealed that the composite exhibited a narrowed band gap of 2.09 eV compared to TiO2(3.54 eV) and PrCrO3 (1.84 eV), indicating improved absorption in the visible region. A reduced photoluminescence intensity further suggested more efficient charge separation. In photocatalytic tests, the TiO2/PrCrO3 system achieved 92.0% MG removal within 120 min, outperforming TiO2(59.62%) and PrCrO3 (73.51%). The apparent reaction rate constant (2.10 & times; 10-2 min-1) was significantly higher than that of TiO2and the catalyst-free system. The optimal catalyst loading was identified as 50 mg. Scavenger experiments demonstrated the participation of center dot OH, center dot O2-, and h+ species, as evidenced by decreased degradation efficiency in their presence. The enhanced photocatalytic activity is attributed to improved interfacial charge separation in the TiO2/PrCrO3heterojunction. Based on the theoretically estimated band-edge positions and reactive-species trapping results, a direct Z-scheme pathway is proposed, in which electrons remain in the conduction band of PrCrO3 and holes remain in the valence band of TiO2, preserving the redox potentials required for center dot O2-and center dot OH generation. Overall, the TiO2/PrCrO3 nanocomposite shows strong potential as an efficient visible-light-driven photocatalyst for dye removal.
