Dissolved ferrous ions in water pose significant environmental and operational challenges, necessitating efficient and sustainable removal technologies. In this study, a hybrid adsorbent was developed by integrating Zn-Al layered double hydroxide (LDH) with hydrochar derived fromrambutan peel (Nephelium lappaceum L.) via coprecipitation. Characterization confirmed successful composite formation with a substantial increase in specific surface area from 9.621 m2.g-1 for pristine Zn-Al LDH to 52.964 m2.g-1 for the composite, accompanied by enlarged pore volume and enriched oxygen-containing functional groups. Batch adsorption experiments showed strong pH dependence, with optimal Fe(II) removal at pH 6 and equilibrium reached within 120 min. The Zn-Al LDH@NL-HC composite exhibited a markedly higher adsorption capacity (51.501 mg.g-1) compared with Zn-Al LDH (15.692 mg.g-1) and hydrochar alone (8.594 mg.g-1), indicating a significant synergistic effect. Isotherm analysis revealed a maximum adsorption capacity of 76.336 mg.g-1 at elevated temperature, while kinetic data followed a pseudo-second-order model, suggesting chemisorption-dominated uptake. Thermodynamic parameters indicated an endothermic and spontaneous process. Regeneration studies demonstrated excellent stability, with adsorption efficiency maintained at 79.48% after five cycles. The superior performance is attributed to combined mechanisms including electrostatic attraction, surface complexation with oxygen-rich groups, ion exchange within LDH interlayers, and diffusion into mesoporous structures. These findings demonstrate the effective valorization of agricultural waste into a high-performance and reusable adsorbent for Fe(II) remediation in aqueous systems.
Silver nanoparticles (AgNPs) have been widely used in developing antibacterial preparations. AgNPs are used in film preparation to enhance the film’s antibacterial properties. The combination of natural polymers is an effective strategy to enhance mechanical properties, prolong degradation time, preserve gas and vapor permeability, and maintain biocompatibility. This research aims to develop an AgNP-chitosan-carboxymethyl chitosan (CMChi) nanocomposite film that exhibits desirable physical properties and enhances antibacterial activity by incorporating AgNPs. Chitosan-CMChi composite films were prepared using the solvent casting method. Characterization and antibacterial tests using Propionibacterium acnes (P. acnes) were carried out for AgNO3 and AgNP-chitosan-CMChi nanocomposite films. The results showed that a 1 mM AgNO3 solution with 1% lime powder at pH 9 was the optimal formulation for AgNP formation, exhibiting an absorbance of 4.631 at 408.1 nm, a particle size of 68.4 nm, and antibacterial activity. To optimize the chitosan-CMChi composite film, a formula of 1.5% chitosan and 1.5% CMChi was selected, yielding a tensile strength value of 0.514 MPa. The AgNP solution was then added. In the AgNP-chitosan-CMChi nanocomposite film, it was observed that increasing the AgNP volume affected the mechanical strength of the film. The antibacterial activity of the AgNP-chitosan-CMChi nanocomposite film increased with the AgNP concentration. Combining AgNPs with the chitosan-CMChi polymer yields nanocomposite films with good physical properties and enhanced antibacterial activity against P. acnes compared with films without AgNPs.
The generalized k-token graph GFk(G) is a graph with the k-subsets of V(G) as the vertices, and two different vertices are adjacent if and only if the symmetric difference contains at least one edge of G. This model extends the classical k-token graph by relaxing the adjacency condition, leading to increased edge density and altered topological properties. In this paper, we establish the fundamental properties of GFk(G), including its connectivity, duality, and monotonicity. We provide exact formulas for the vertex degrees and the total size of GF2(G), along with combinatorial bounds for k > 2. Furthermore, we characterize the girth and clique numbers, proving that GFk(G) is highly prone to containing triangles even when the base graph is triangle-free. We also explore the inheritance of Hamiltonicity and bipartiteness, demonstrating that while connectivity is preserved, bipartiteness is lost for almost all bipartite graphs with at least four vertices. Our results provide a comprehensive structural characterization of this generalization, bridging the gap between classical token graphs and broader set-theoretic graph constructions.
The mesenchymal stem cells (MSCs) secretome plays multiple roles in tissue regeneration and wound healing due to its content of various bioactive factors, including Fibroblast Growth Factor-2 (FGF-2). To support its topical application, an effective delivery system is required to preserve the stability and bioactivity of the secretome. A hydrogel sponge based on PVA-HPMC-PEG was selected as the delivery matrix due to its porous structure, flexibility, and ability to release active substances, thereby making it a promising candidate for wound healing applications. The objective of this research was to formulate a PVA-HPMC-PEG-based hydrogel sponge for a secretome delivery system. The hydrogel sponge was prepared using the freeze-drying method and optimized by varying the PVA concentration to achieve the desired physicochemical characteristics. The optimal formulation (F4) consists of 20% PVA, 2% HPMC, and 7.5% PEG. Evaluation revealed that this formulation exhibited a flexible sponge-like structure with a swelling percentage of 279.793% ± 0.06, elongation percentage of 107.923% ± 4.98, and physical crosslinking confirmed by FTIR analysis. Scanning Electron Microscopy (SEM) analysis demonstrated pore size ranging from 20 to 215 μm. Furthermore, secretome release was assessed using a Franz diffusion cell, and FGF-2 levels were quantified via ELISA. The results confirmed that the hydrogel sponge effectively facilitated the release of the secretome.
Graph labeling is the process of determining integer values for vertices, edges, or both, based on certain criteria. Let G be a simple graph with the finite vertex set V(G). Prime labeling of G is a bijection ⍺:V(G)→{1,2,…,|V(G)|} for which each pair of adjacent vertices exhibits relatively prime labels. This concept has been extended to odd prime labeling, defined as a bijection ⍺:V(G)→ {1,3,...,2|V(G)|-1} satisfying the condition that the labels assigned to adjacent vertices are relatively prime labels. A graph that displays a (odd) prime labeling is designated as a (odd) prime graph. A recent conjecture state that every prime graph is an odd prime graph. In the present study, we conduct an investigation concerning prime and odd prime labeling, focusing on a range of cycle-related graphs classes. Our methods include the axiomatic descriptive approach and pattern detection techniques. We show that volcano graphs, C_3 ⨀_(x_1 y_0 ) F_n, C_3⊚K ̅_n, tadpole graphs, palm trees, and C_l ⨀_(x_1 y_0 ) mP_(n+1) are all both prime and odd prime graphs.
