Search Results (202)

Novel highly compressible and stretchable nanocomposite (NC) hydrogels were obtained by the free radical polymerization of N-vinylformamide (NVF) in aqueous solution in the presence of Laponite XLG (XLG) as the crosslinker and 2,2′-azobis(2-methylpropionitrile) as the initiator. The expected composition of the NC hydrogels was proved by FTIR, TEM, XRD, and TGA analyses. Swelling degree (SD) and mechanical measurements showed that the properties of the PNVF NC hydrogels were largely different from those of both PNVF hydrogels covalently crosslinked by N,N’-methylenebisacrylamide (MBA) and equivalent poly(N-vinyl-2-pyrrolidone) (PNVP) NC hydrogels. After an initial fast swelling stage, the PNVF NC hydrogels displayed a slow, but steady, SD increase with time, unlike the MBA-crosslinked and NVP hydrogels, which exhibited a much smaller SD change during their second swelling stage. The mechanical testing of the synthesized hydrogels by uniaxial compressive and tensile measurements showed much higher compressibility (>90%) and stretchability (up to ≈840%) in the PNVF NC hydrogels than both PNVP and MBA-crosslinked PNVF hydrogels (compressibility < 80%; stretchability up to ≈114%). Cyclic compression tests revealed higher values for both elastic character and mechanical stability in the PNVF NC hydrogels in comparison to the MBA-crosslinked and PNVP ones. These different mechanical properties were explained by the PNVF NC gels possessing a network made of homogeneously distributed crosslinking sites and flexible polymer chains, thus avoiding extensive chain breakage up to larger stress values. The PNVF NC hydrogels described here may find applications for water purification, due to their high clay content, as well as in the biomedical field based on the biocompatibility of both the polymer and crosslinking agent. Full article

Textile dye effluents, particularly cationic dyes, pose a major environmental challenge, demanding efficient and sustainable adsorbent materials to remove harmful synthetic dyes. In this study, a reference thiourea–formaldehyde (TU/FA) composite and a series of thiourea–poly(acrylic acid)–formaldehyde (TU/PAA/FA) composites were synthesized and systematically characterized. The composites were prepared by varying the volume of poly(acrylic acid) PAA (from 1 to 7.5 mL) to assess how PAA incorporation influences morphology, crystallinity, surface chemistry, charge, and thermal stability. Analytical techniques including SEM, XRD, FT-IR, particle size distribution, zeta potential, and TGA/DTG revealed that increasing PAA content induced more porous and amorphous microstructures, intensified carbonyl absorption, reduced particle size (optimal at 2.5–5 mL PAA), and shifted the zeta potential from near-neutral to highly negative values (−37 to −41 mV). From TU/PAA/FA composite analysis, it was depicted that the TU/PAA-5/FA material has the better characteristics as a potential cationic dye absorbent. Thus, the adsorption performance of this composite toward crystal violet dye was subsequently investigated and compared to the reference material thiourea–formaldehyde (TU/FA). The TU/PAA-5/FA material exhibited the highest capacity (145 mg/g), nearly twice that of TU/FA (74 mg/g), due to the higher density of carboxylic groups facilitating electrostatic attraction. Adsorption was pH-dependent, maximized at pH 6, and decreased with temperature, confirming an exothermic process. Kinetic data followed a pseudo-second-order model (R² = 0.99), implying chemisorption as the rate-limiting step, while Langmuir isotherms (R² > 0.97) indicated monolayer adsorption. Thermodynamic analysis (ΔH° < 0, ΔS° < 0, ΔG° > 0) further supported an exothermic, non-spontaneous mechanism. Overall, the TU/PAA-5/FA composite combines enhanced structural stability with high adsorption efficiency, highlighting its potential as a promising, low-cost material for the removal of cationic dyes from textile effluents. Full article

Bacteria such as Salmonella spp. are primarily transmitted through contaminated eggs and infected poultry; however, other routes, including the movement of personnel, vehicles, and lapses in biosecurity protocols, also play a significant role in their dissemination within poultry systems. Control of a wide range of microorganisms, including bacteria, is often carried out using chemical agents, such as formaldehyde, applied in its solid, liquid, or gaseous forms. Reports on the use of formaldehyde in poultry production date back more than a century. However, it continues to attract research interest due to growing concerns about bacterial resistance, embryotoxicity, occupational exposure, the generation of toxic byproducts, and the search for safer alternatives in poultry production systems. It remains widely used worldwide, but comprehensive and updated evaluations of its efficacy, toxicity, and risks to both poultry and workers are still limited. This review aims to synthesize the current knowledge on the use of formaldehyde in poultry production. Overall, the synthesis shows that formaldehyde remains an effective but high-risk sanitizer whose continued use in poultry systems requires rigorous control and monitoring protocols, and that the development and adoption of efficient and safer alternatives is recommended. Full article

Cyanothioacetamide readily reacts with aromatic aldehydes in an aqueous–alcoholic medium in the presence of triethylamine as a catalyst, resulting in arylmethylene cyanothioacetamides (3-aryl-2-cyanothioacrylamides). The latter react with formaldehyde (HCHO), yielding N-(hydroxymethyl) derivatives. This work proposes a method for the preparation of new derivatives of N-(hydroxyalkyl)thioacrylamides. The details of the synthesis and spectral data are discussed. Biological effects are also considered as 2,4-D herbicide antidotes (safeners). Full article

The year 2024 marked the 80th anniversary of Woodward’s total synthesis of quinine. Quinine is a natural alkaloid from the bark of the cinchona tree that has been used for years as an antimalarial drug. The antibacterial effect of quinine salts has also been regarded. With this in mind, a series of original 9-deoxycinchone alkaloid derivatives bearing a dialkylamino- or heterocyclic moiety at the 4 position of the 9-(((4-X-but-2-ynyloxy)methyl)-1,2,3-triazolyl)-substituent was synthesized. The copper-catalyzed three-component A³-coupling reaction of 9-(((4-prop-2-ynyloxy)methyl)-1,2,3-triazolyl)- substituted cinchona alkaloid derivatives with secondary amines and formaldehyde was the main route of synthesis. The present study attempted to examine the antibacterial properties of 9-substituted 9-desoxyquinine-derived compounds and their antibacterial activity against pathogenic bacterial strains, e.g., Staphylococcus aureus, Bacillus subtillis, Bacillus cereus, and Escherichia coli. The difference in the antibacterial activity profile of diastereoisomeric 9-(((4-X-but-2-ynyloxy)methyl)-1,2,3-triazolyl)-substituted derivatives of cinchona alkaloids indicated the importance of the nature of nitrogen substituents in the molecules. In a concentration-dependent pattern, (9R)- and (9S)- (((4-asocan-1yl)-but-2-ynyl-oxy)methyl)-1,2,3-triazolyl)-substituted compounds demonstrated considerable biofilm-inhibitory efficacy against the S. aureus bacterial strain. A detailed study of the molecular interactions with the targeted protein MurB was performed using docking simulations, and the obtained results are quite promising. Full article

Comets are chemically rich and thermally extreme, spanning surface temperatures from ~50 K in the Oort Cloud to >1000 K for sungrazing bodies. These conditions may support key steps of prebiotic chemistry, including the synthesis of nucleic acid precursors. This study present a thermodynamic evaluation of seven candidate reactions, producing nitrogenous bases, sugars, nucleosides, and nucleotides, across the cometary temperature spectrum, 50–1000 K. Purine nucleobase synthesis, including adenine formation via aminoacetonitrile polymerization and HCN polymerization, is strongly exergonic at all temperatures. Sugar formation from formaldehyde is also exergonic, while intermediate pathways, e.g., 2-aminooxazole synthesis, become thermodynamically viable only above ~700 K. Nucleoside formation is thermodynamically neutral at low T but becomes favorable at elevated temperatures, whereas phosphorylation to AMP, i.e., adenosine-monophosphate, a nucleotide serving as a critical regulator of cellular energy status, remains highly endergonic under the entire T range studied. My analysis suggests that, under standard-state assumptions, comets can thermodynamically support formation routes of nitrogenous bases and simple sugars but not a complete nucleotide assembly. This supports a dual-phase origin scenario, where comets act as molecular reservoirs, with further polymerization and biological activation occurring post-delivery on planetary surfaces. Importantly, these findings represent purely thermodynamic assessments under standard-state assumptions and do not address kinetic barriers, catalytic influences, or adsorption effects on ice or mineral surfaces. The results should therefore be viewed as a baseline map of feasibility, subject to modifications in more complex chemical environments. Full article

The chemical bath deposition of ZnO nanowires is of high interest for many functional devices, but the typical use of hexamethylenetetramine (HMTA) molecules forming formaldehyde as a harmful substance raises health, environment, and regulation issues. After a careful review of the multiple roles of HMTA molecules, we unambiguously show, using X-ray near-edge structure absorption spectroscopy with synchrotron radiation, that they do not form any complexes with the Zn(II) species, both in the low- and high-pH regions. In contrast and in agreement with thermodynamic computations, [Zn(H₂O)₆]²⁺ and Zn(NH₃)₄²⁺ ion complexes are revealed to be the predominant Zn(II) species in the low- and high-pH regions. The use of HMTA molecules is found to be critical to form ZnO nanowires with a high aspect ratio in the low-pH region. In contrast, HMTA molecules are shown to be fully substituted by ammonia in the high-pH region to form ZnO nanowires with a high structural and optical quality. The removal of HMTA molecules for the chemical bath deposition of ZnO nanowires in the high-pH region represents a significant step forward towards the development of a chemical synthesis fully compatible with green chemistry. Full article

As a continuation of our research on the synthesis and study of biological properties of new derivatives of 3-aminopyridin-2(1H)-ones, we investigated the Leuckart–Wallach and Eschweiler–Clarke reactions with selected 3-aminopyridin-2(1H)-ones and 3-(arylmethyl)pyridin-2(1H)-ones. It was found that under the conditions of the Leuckart–Wallach reaction with aromatic aldehydes in formic acid, mainly formamides of the indicated 3-aminopyridones are formed. The Eschweiler–Clarke reaction of 3-aminopyridin-2(1H)-ones and 3-(arylmethyl)pyridin-2(1H)-ones with an aqueous solution of formaldehyde result in the formation of tertiary N–benzyl(methyl)amino)-pyridin-2(1H)-ones in almost quantitative yield. The 3-aminopyridin-2(1H)-ones derivatives synthesized by us were used for the biological screening of cytoprotective activity in the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test to determine the viability of fibroblast cells isolated from the NIH/Swiss mouse embryo (NIH/3T3, Gibco). It was found that many of the studied compounds under the conditions of our experiment exhibited significant cytoprotective effects, thereby enhancing cell survival. Full article

Resol phenol–formaldehyde (PF) resin was modified with 2.5 and 5.0 wt% polymethylhydrosiloxane (PMHS). This study characterizes the modified resin and its subsequently fabricated glass fiber (GF)-reinforced composites (30–60 wt% GF). Formation of an organic–inorganic hybrid network, via reaction between Si-H groups of PMHS and hydroxyl (-OH) groups of the resol resin, was confirmed by FTIR and ¹H NMR. DSC and TGA/DTG revealed enhanced thermal stability for PMHS-modified resin: the decomposition temperature of Resol–PMHS 5.0% increased to 483 °C (neat resin: 438 °C), and char yield at 800 °C rose to 57% (neat resin: 38%). The 60 wt% GF-reinforced Resol–PMHS 5.0% composite exhibited tensile, flexural, and impact strengths of 145 ± 7 MPa, 160 ± 7 MPa, and 71 ± 5 kJ/m², respectively, superior to the unmodified resin composite (136 ± 6 MPa, 112 ± 6 MPa, and 51 ± 5 kJ/m²). SEM observations indicated improved fiber–matrix interfacial adhesion and reduced delamination. These results demonstrate that PMHS modification effectively enhances the thermo-mechanical properties of the PF resin and its composites, highlighting potential for industrial applications. Full article

Formaldehyde is illegally applied to vegetables by vendors as a preservative to extend their shelf life, and it poses health risks to consumers. Herein, a series of WO₃ with different morphologies were synthesized and employed as the sensing material in gas sensors to detect formaldehyde in vegetables rapidly. Among all the samples, the WO₃ nanoplate sensor exhibited the best sensitivity (16.5@200 ppm), a rapid response/recovery time (10/12 s), superior selectivity, and a low limit of detection (500 ppb). This was mainly attributed to its abundant mesopores and large specific surface area, which enhanced the formaldehyde adsorption capacity and adsorption/desorption rates while providing more active sites, thereby improving the sensor’s response speed and resistance variation range. The WO₃ nanoplate sensor also achieved reliable formaldehyde detection in actual vegetable samples (baby cabbage). This study provides systematic guidance for optimizing the gas-sensing performance of functional materials. It establishes a foundation for developing rapid, non-destructive formaldehyde detection technologies applicable for vegetable quality control. Full article

Wood adhesives play a critical role in the wood processing industry; however, traditional formaldehyde-based adhesives pose health risks and are reliant on non-renewable resources. This study aims to develop a bio-based wood adhesive with excellent water resistance, focusing on environmentally friendly solutions. The synthesis of an oxidized starch-lignin (OSTL) composite adhesive was accomplished by modifying starch via oxidation and subsequent cross-linking with lignin. Ammonium persulfate (APS) was employed for oxidation of starch, introducing aldehyde groups that upgrade its reactivity with lignin. Subsequently, the oxidized starch (OST) was cross-linked with the phenolic rings of lignin, resulting in a strong network structure. The oxidation of starch and its cross-linking mechanism with lignin were investigated using the Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H-NMR), and X-ray photoelectron spectroscopy (XPS) techniques, proving the formation of aldehyde and carboxyl groups with subsequent reaction possibilities. The effects of oxidant dosage, oxidation time, and the ratio of starch to lignin on the adhesive properties were systematically studied. The results demonstrated that the OSTL adhesive, prepared under optimized conditions, exhibited outstanding adhesion strength (1.23 MPa in dry state) and water resistance (0.94 MPa after 24 h cold water immersion, 1.04 MPa after 3 h in hot water, and 0.69 MPa after 3 h in boiling water), significantly outperforming conventional wood adhesives in terms of cold water, hot water, and boiling water resistance. In addition, the thermal behavior of the OSTL adhesive was further validated using differential scanning calorimetry (DSC) as well as thermogravimetric analysis (TGA). This study presents new insights and technical support for the development of green, environmentally friendly, and highly water-resistant lignin-based bio-adhesives. Full article

This work reports a study on the structural characterization, evaluation of thermal stability, and non-isothermal decomposition kinetics of urea–formaldehyde (UF) resin modified with hydrochar (obtained by the hydrothermal carbonization of spent mushroom substrate (SMS)) (UF-HC). The structural characterization of UF-HC, performed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction analyses, showed that UF-HC consists of a large number of spheroidal particles, which are joined, thus forming clusters. It constitutes agglomerates, which are composed of crystals that have curved plate-like forms, including crystalline UF structure and graphite lattices with an oxidized face (graphene oxide, GO). The measurement of inherent thermal stability and non-isothermal decomposition kinetic analysis was carried out using simultaneous thermogravimetric–differential thermal analyses (TGA-DTA) at various heating rates. Parameters that are obtained from thermal stability assessment have indicated the significant thermal stability of UF-HC. Substantial variation in activation energy and the pre-exponential factor with the advancement of decomposition process verifies the multi-step reaction pathway. The decomposition process takes place through three independent single-step reactions and one consecutive reactions step. The consecutive stage represents a path to the industrial production of valuable heterocyclic organic compounds (furan) and N-heterocyclic compounds (pyrroles), building a green-protocol trail. It was found that a high heating rate stimulates a high production of furan from cellulose degradation via the ring opening step, while a low heating rate favors the production of urea compounds (methylolurea hemiformal (HFn)) by means of methylene ether bridges breaking. Full article

Formaldehyde, a pervasive indoor air pollutant posing significant health risks, has driven extensive research into advanced mitigation strategies to ensure safer living environments. Herein, this study presents a synthesis method for the large-scale production of hydrogenated TiO₂ (P25) loaded with PtAu nanoalloys (P25(H)-PtAu), using a combination of ball milling and high-temperature annealing. Hydrogenation-induced defect-rich TiO₂ efficiently improves visible light absorption, enhancing the utilization of visible light in photocatalytic reactions. Mechanochemical ball milling was employed to prepare ultrasmall PtAu nanoalloys with a size of 3.7 ± 0.1 nm, which were uniformly dispersed on the surface of P25(H). Density functional theory (DFT) results indicate that PtAu nanoalloys synergistically enhance charge separation via Schottky junctions and surface reaction kinetics by optimizing reactant adsorption. As a result, P25(H)-PtAu achieves industrially relevant formaldehyde removal efficiency (97.8%) under ambient light conditions while maintaining scalability (10 g batches). This work provides a scalable framework for developing manufacturable photocatalysts, with immediate applications in heating, ventilation and air conditioning systems, and air purifiers. Full article

Gold nanoparticles (AuNPs) are a promising tool for drug delivery due to their unique chemical properties that make them biocompatible and easy to functionalize. However, when AuNPs are introduced into biological systems, they are coated by the so-called protein corona (PC), which affects their biodistribution and limits their therapeutic efficacy. The functionalization of AuNPs with endogenous carbohydrates can be a possible strategy to reduce immune recognition, thus enhancing their biocompatibility and circulation time. Suitable candidates for this approach are the ABO blood sugar antigens, di- and tri-saccharides that represent the terminal portion of some glycolipids and glycoproteins present on the surface of human red blood cells and other tissues. In this work, we illustrate the synthesis of trisaccharide antigen A derivative, whose last step is worthy of investigation. During the final hydrogenolysis reaction, intended to remove protecting groups, an unexpected side reaction occurred, the isolated product bearing an N,N-dimethyl moiety on the anomeric propyl linker. This side reaction might be ascribed to the in situ formation of formaldehyde and successive imine formation and reduction. The obtained compound can be used as a monomeric control compound in biochemical and structural biology studies involving ABO blood sugar antigens. Full article

Coatings can achieve the property of changing color with temperature variations by adding thermochromic microcapsules, which can bring a variable surface to the substrate. Ultraviolet ray (UV)-cured primers have the advantages of a fast curing rate, low-temperature curing, and low pollution. Thermochromic microcapsules can expand the application range of UV primers. Thermochromic microcapsules were synthesized through an orthogonal test, using crystal violet lactone, bisphenol A, and decanol as the core materials in a 1:4:50 mass ratio, with urea formaldehyde resin as the wall material. The effects of the addition of batches of the urea, the mass ratio of the formaldehyde solution to the urea, the hydrophilic–lipophilic balance (HLB) value of the emulsifier, and core-to-wall mass ratio on microcapsules yields, encapsulation rates, thermochromic color differences (ΔE), and formaldehyde releases during synthesis were investigated. The results were normalized, with the thermochromic ΔE as the primary reference for analysis. The results indicate that the HLB value of the emulsifier was the key factor that affected the microcapsule performance. In a single-factor test, the HLB value was adjusted within the range of 6.00 to 10.00. It was found that when the HLB value was 10.00, the microcapsules exhibited the best comprehensive performance, with a yield of 43.29%, an encapsulation rate of 45%, a thermochromic ΔE of 4.60, and a formaldehyde concentration released of 1.310 mg/L. The 11# microcapsules with the optimal morphology and better comprehensive performance were compared with the best 14# microcapsules. Different amounts of these microcapsules were added to the UV primer to investigate the effects of the 11# and 14# microcapsules on the mechanical and optical properties of the UV primer. The main component of the UV primer was polyurethane acrylic resin, propylene glycol diacrylate, and hexanediol diacrylate. When 14# microcapsules were added to the UV primer at a concentration of 10%, the primer exhibited the best comprehensive performance, with a fracture elongation of 17.44%, a roughness of 0.15 μm, and a visible light transmittance of 83%. Microcapsule technology was used to modify UV primers, endowing them with thermochromic properties and expanding the application range of thermochromic microcapsules. Full article