Search Results (83)

The agrifood industry shows one of the widest ranges of possible end products from crops, such as fruits, legumes, cereals, and tubers. The raw material is generally collected and processed industrially, producing a significant amount of organic waste. The overall picture is made more complex by the wide variety of nature and composition, and by the difficulty identifying the possible uses of the wastes coming from the processing industry. Such wastes are often disposed of in landfills or treated in waste-to-energy plants depending on the area where they are produced. The circular economy approach has suggested numerous possible generic strategies to improve waste management, involving the exploitation of waste to obtain new value-added products. The use of fibers from legume waste from the canning industry in the bioplastics production sector is a promising and relatively little explored line, particularly for the fibers of beans and green beans. With this in mind, in this article, green bean and borlotti bean fibers obtained from the treatment of wastes were used as reinforcing material for polycaprolactone (PCL)-based biocomposites by melt blending. Analyses were carried out about the morphological, spectroscopic, thermal, and mechanical properties of the starting and the obtained materials. Full article

Bioconjugation reactions are critical to the modification of peptides and proteins, permitting the introduction of biophysical probes onto proteins as well as drugs for use in antibody-targeted medicines. A diverse set of chemical reagents can be employed in these circumstances to covalently label protein side chains, such as the amine moiety in the side chain of lysine and the thiol functionality in cysteine residues, two of the more frequently employed sites for modification. To provide researchers with a thermodynamic survey of the reaction of these residues with frequently employed chemical modification reagents as well as reactive cellular intermediates also known to modify proteins non-enzymatically, a theoretical investigation of the overall thermodynamics of models of these reactions was undertaken at the T1 and G3(MP2) thermochemical recipe levels (gas phase), the M06-2X/6-311+G(2df,2p)/B3LYP/6-31G(d) (gas and water phase), and the M06-2X/cc-PVTZ(-f)++ density functional levels of theory (water phase). Discussions of the relationship between the reagent structure and the overall thermodynamics of amine or thiol modification are presented. Of additional interest are the observations that routine cellular intermediates such as certain thioesters, acyl phosphates, and acetyl-L-carnitine can contribute to non-enzymatic protein modifications. These reactions and representative click chemistry reactions were also investigated. The computational survey presented herein (>320 reaction computations were undertaken) should serve as a valuable resource for researchers undertaking protein bioconjugation. A concluding section addresses the ability of computation to provide predictions as to the potential for protein modification by new chemical entities, with a cautionary note on protein modification side reactions that may occur when employing synthetic substrates to measure enzyme kinetic activities. Full article

Computer modeling, machine learning, and artificial intelligence are currently considered cutting-edge topics in chemistry and materials science. The application of information technologies in natural sciences can help researchers collect big data and understand patterns that are not obvious to humans. In this perspective, I would like to highlight the recent achievements of our research group and other researchers in relation to computer modeling and machine learning in chemistry and materials science. Full article

Glyptostrobus pensilis (Staunton ex D. Don) K. Koch is a critically endangered species, native to southeastern China and also very locally found in Dak Lak Province, Vietnam. Essential oil isolated from leaves is a monoterpene-rich oil containing mainly limonene (33.3%), α-pinene (23.4%) and bornyl acetate (9.2%). The composition of G. pensilis wood oil is rather complex and the identification of individual components needed fractionation over column chromatography. The main components, identified by GC(RI), GC-MS and ¹³C NMR, were cedrol (29.3%), occidentalol (6.6%) and occidentalol isomer (5.9%). Full article

This study presents a comprehensive analysis of the synthesis and photophysical properties of thiazolidine-functionalized chiral ionic liquids (CILs) derived from L-cysteine. The synthesis involves a four-step route, encompassing N-protection, coupling reactions with bromoalcohols, and ionic liquid formation. The optical properties of the compounds were evaluated using UV–Vis absorption and fluorescence emission spectroscopies, revealing distinct behavior for different heterocycles and counter-ions. Notably, the investigation reveals that thiazolidine-based CILs exhibit unconventional intrinsic luminescence characteristics. Building upon these photophysical properties, an interaction study was conducted between copper (II) and the CILs. The findings exhibit a robust linear relationship between the optical response and the concentration of the metal ion. Through the calculation of the Stern–Volmer quenching constant, it was determined that the 1:1 binding model is applicable. This research underscores the potential of UV–Vis absorption spectroscopy as a highly sensitive method for detecting metal ions. By elucidating the synthesis, photophysical behavior, and metal ion interaction of thiazolidine-based CILs, this study contributes valuable insights into the field of functionalized ionic liquids and their potential applications in various areas. Full article

The scientific community recognizes coffee grounds (Coffea arabica) as an important biological residue, which led to using the Eversa^® Transform 2.0 lipase as an in silico enzymatic catalyst for coffee grounds’ free fatty acids (FFA). Molecular modeling studies, including molecular docking, were performed, which revealed the structures of the lipase and showed the primary interactions between the ligands and the amino acid residues in the active site of the enzyme. Of the ligands tested, 6,9-methyl octadienoate had the best free energy of −6.1 kcal/mol, while methyl octadecenoate and methyl eicosanoate had energies of −5.7 kcal/mol. Molecular dynamics confirmed the stability of the bonds with low Root Mean Square Deviation (RMSD) values. The MMGBSA study showed that methyl octadecenoate had the best free energy estimate, and CASTp identified key active sites for potential enzyme immobilization in experimental studies. Overall, this study provides efficient and promising results for future experimental investigations, showing a classification of oils present in coffee grounds and their binding affinity with Eversa. Full article

Air filtration is an urgent global need because, in many countries and regions, the high concentration of inhalable suspended particles in the air is causing irreversible damage to human health. The use of nanofibrous membranes can help to reduce airborne particulate matter because of their large surface area, extremely porous structure, and adjustable pore size. However, despite their unique properties, the main drawbacks of nanofibre membranes are their poor mechanical properties. This review focuses on nanofibrous membranes prepared by electrospinning, a versatile technique in which the process parameters allow control of the morphology and dimensional characteristics of the nanofibres. Recent literature on air filtration is reviewed, focusing on the performance of materials such as pure or mixed polymers, organic–inorganic composites, and ‘green’ materials in the form of nanofibrous membranes. Finally, the recently proposed layered structures for nanofibre-based air filters are reviewed, offering the latest and most innovative solutions. Full article

The condensation product of the reaction between aniline and salicylaldehyde was a 2-(2-hydroxybenzylidinemine)—aniline Schiff base bidentate ligand (L). L was used to generate complexes by interacting with the metal ions lanthanum(III), zirconium(IV), yttrium(III), and copper(II), in addition to cobalt(II). Various physicochemical techniques were utilized to analyze the synthesized L and its metal chelates, including elemental analysis (CHN), conductimetry (Λ), magnetic susceptibility investigations (μ_eff), Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (¹H NMR) spectroscopy, ultraviolet–visible (UV-Vis.) spectrophotometry, and thermal studies (TG/DTG). FT-IR revealed that the L molecule acted as a bidentate ligand by binding to metal ions via both the oxygen atom of the phenolic group in addition to the nitrogen atom of the azomethine group. Additionally, ¹H NMR data indicated the formation of complexes via the oxygen atom of the phenolic group. An octahedral geometrical structure for all of the chelates was proposed according to the UV-Vis. spectra and magnetic moment investigations. Thermal analysis provided insight into the pattern of L in addition to its chelates’ breakdown. In addition, the investigation furnished details on the chelates’ potential chemical formulas, the characteristics of adsorbed or lattice H₂O molecules, and the water that is coordinated but separated from the structure at temperatures exceeding 120 °C. The thermodynamic parameters utilizing Coats–Redfern in addition to Horowitz–Metzger equations were studied. The antimicrobial effectiveness of L and its chelates against distinct species of bacteria and fungi was studied using the disc diffusion method. Cu(II) and Y(III) chelates had significant antimicrobial activity against Staphylococcus aureus and Micrococcus luteus. Full article

Cladanthus mixtus (L.) Chevall., Asteraceae, also known as Moroccan chamomile, is a spontaneous, annual plant growing wild in North-Western Morocco. Economically, the essential oil of C. mixtus is of high interest, Morocco being the only supplier on the international market. Two essential oil samples (EO) were isolated from aerial parts of Cladanthus mixtus (L.) Chevall., and analyzed by a combination of chromatographic and spectroscopic techniques (gas chromatography (GC) in combination with retention indices (RI), gas chromatography-mass spectrometry (GC/MS), and ¹³C NMR spectroscopy). Computer matching against the in-house ¹³C NMR library allowed the identification of the eight components at appreciable contents, namely 3,6,6,9-bis-epoxy-farnesa-1,7(14),10-triene, and its 3-epi, 9-epi, and 3,9-diepi epimers, and 6,9-epoxy-farnesa-1,7(14),10-trien-3-ol and its 3-epi, 6-epi, and 3,6-diepi epimers. Our results confirm the tremendous chemical variability of Moroccan C. mixtus essential oil and the usefulness of ¹³C NMR analysis, in combination with GC(RI), for the identification of uncommon oxygenated sesquiterpenes that induce an original composition. Full article

Following the trend of finding better thermoelectric materials among synthetic analogs of copper–chalcogenide minerals, we have synthesized iron-bearing colusites of a general formula Cu_26−xFe_xV₂Sn₆S₃₂. They crystallize in the cubic space group P-43n with the unit cell parameter increasing linearly with the iron content. At a low iron concentration, the crystal structure features disorder manifested by an anti-site effect and a shift of a part of the tin atoms from their ideal positions, which is absent for higher iron contents. The magnetization and ⁵⁷Fe/¹¹⁹Sn Mössbauer studies showed that, for x = 1, iron is present as Fe³⁺, whereas for x > 1, Fe²⁺ and Fe³⁺ coexist. Additionally, weak antiferromagnetic interactions between iron atoms and fast on the ⁵⁷Fe Mössbauer time scale (10⁷–10⁹ s⁻¹) electron transfer between adjacent Fe²⁺ and Fe³⁺ centers were revealed. Thermoelectric studies showed that iron-bearing colusites are p-type semiconductors with low thermal conductivity stemming from their complex crystal structure and structural disorder. The highest ZT of 0.78 at 700 K was found for the x = 1 iron content, where iron is present as Fe³⁺ only. Full article

We performed an enzymatic screening of synthetic peptides based on β-amyloid precursor protein substrates. The template peptide sequence was a decapeptide derived from our previous screening study, which determined several effective unnatural amino acids. In this study, new libraries containing some unnatural amino acid compounds were prepared in the solid phase and digested with the β-site amyloid precursor protein-cleaving enzyme. The reaction mixture was analyzed using high-performance liquid chromatography combined with mass spectrometry. The peptides that showed a higher cleavage than the template sequence were determined and reported. Full article

Infinitene was synthesized in a previous study in 2021, and the molecule showed high strain energy. It was not clear how the strain affected the aromatic character of the molecule. To discuss this problem, the aromatic properties of dodecacene, [12]circulene, and infinitene have been studied. The structures of these compounds have been optimized at the DFT/B3LYP/6-311G + (d,p) level of theory, and the energy of the π orbitals has been used to determine the D’ index of the aromaticity. D′ for dodecacene, [12]circulene, and infinitene were 1.45, 1.45, and 1.50, respectively, showing that infinitene is an aromatic compound but with a lower aromatic character, which is in agreement with the observed strain. Full article

Diseases caused by infections are becoming harder to treat as the antibiotics used become less effective. A combination of strategies to develop active biomaterials that enhance antibacterial effects are desirable, especially ones that cause fewer side effects and promote healing properties. The combination of nanotechnology with substances that have intrinsic antibacterial activity can result in the advance of innovative biomedical materials. In this sense, the goal of this work is to provide a summary of natural rubber latex materials obtained from the Hevea brasiliensis tree loaded with metallic and metal oxide nanoparticles. These nanoparticles have unique size-dependent chemical and physical characteristic that make them appropriate for use in pharmaceutical and medical devices, while natural rubber latex is a natural and biocompatible polymer with an intrinsic antibacterial effect. Moreover, we outline here the origin, extraction methods, and composition of natural rubber latex and different techniques for the synthesis of nanoparticles, including physical, chemical, and biological approaches. Finally, we summarize, for the first time, the state of the art in obtaining natural rubber-based materials with metallic and metallic oxide nanoparticles for biomedical applications. Full article

Coordination compounds of Co(II), Cu(II), Y(III), Zr(IV) and La(III) ions were synthesized from the N-salicylidene aniline (L) derived from the condensation of aniline with salicylaldhyde and 1,10-phenanthroline (phen) as a secondary mixed ligand. L, phen and their complexes were characterized using various physiochemical methods, such as elemental analyses (CHN), Fourier-transform infrared spectroscopy (FT-IR), molar conductance (Λ), magnetic susceptibility (μeff), proton nuclear magnetic resonance (¹H NMR), ultraviolet–visible spectroscopy (UV–Vis) and thermogravimetric analysis (TG/DTG). The analytical and spectroscopic data supporting the chemical formulas of the metal complexes and chelation of L and phen with the metal ions forming octahedral complexes. FT-IR spectra demonstrated that L chelated with metal ions as a bidentate ligand via the oxygen atom of the phenolic group with a band in the range 3378–3437 cm⁻¹ and the nitrogen atom of the azomethine group at 1612 cm⁻¹. In addition, phen chelated through two nitrogen atoms in the range 1525–1565 cm⁻¹. The ¹H NMR results confirmed the IR assumption that the ligand connected to the metal ions via the phenolic’s oxygen atom. The molar conductance measurements of the complexes revealed high values of the electrolytic nature of these complexes in the range of 90.40–125.80 S cm² mol⁻¹. Thermal analysis (TG/DTG) was used to differentiate between coordinated and hydrated water molecules and the thermal stability of the complexes. Finally, the anti-microbial activities of the complexes were investigated against fungi (Candida albicans), Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) and Gram-positive bacteria (Staphylococcus aureus and Micrococcus sp.) using the disc diffusion method. The La(III) complex was significant against C. albicans compared with all other compounds and reference standard control. Full article