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Crystal structure and physicochemical properties of Cu(II) azo pyridone dye complex
No full textThe design of new biologically active compounds through coordination of heterocyclic azo dyes with transition metals represents an important research direction, since complexation often enhances or modifies the pharmacological potential of the ligands [1]. Transition metal complexes of azo dyes have been reported to exhibit antimicrobial, anti-inflammatory, antioxidant, and antitumor activities [2], in addition to their wellestablished application in dyeing, optics, and recording media. Within this group, azo pyridone dyes are recognized as promising chelating agents, where the azo-hydrazone tautomerism governs the coordination process. In the reaction of 5-(4-chlorophenylazo)-1-ethyl-3-cyano-6-hydroxy-4-methyl-2- pyridone (HL) with
Cu(CH₃COO)₂·H₂O in N,N-dimethylformamide (DMF) at room temperature, a complex [CuL₂(DMF)]·DMF was prepared [3]. The complex was characterized by UV–Vis and ATR–FTIR spectroscopy, simultaneous TG/DSC, and single- crystal X-ray diffraction. The asymmetric unit of the complex comprises one Cu(II) atom, two chelate ligands (L), one coordinated and one noncoordinated DMF molecule (Figure 1). The Cu(II) atom adopts a squarepyramidal
geometry, defined by two N and two O donor atoms from the ligands and one O atom from the solvent. The crystal packing is stabilized by weak noncovalent interactions, including C–H···O/N, π–π stacking, C–H···π contacts, and Cl···Cl interactions
Tailoring Supramolecular Assemblies of Drug-like Spirohydantoin Derivatives
No full textTo expand biologically relevant chemical space of hydantoin derivatives, we designed and synthesized a series of molecules built around this scaffold with a tetralin moiety in a spiro arrangement and a 4-substituted benzyl group (Figure 1). Such a molecular design enabled us to study the infuence how conformational fexibility and substitution patterns infuence intermolecular interactions and supramolecular organization. Single-crystal X-ray diffraction revealed that these structures are primarily stabilized by N–H∙∙∙O hydrogen bonds, forming either discrete R22(8) dimers or infinite chain motifs. However, medium to weak interactions proved to be decisive in constructing extended supramolecular architectures, especially in the case where these hydrogen bonds were absent. Computational analyses provided complementary insights: interaction energy calculations and molecular electrostatic potential (MEP) surface mapping clarified the hierarchy of hydrogen bonds involving different acceptor sites.
Overall, this study highlights the role of substituent effects and electronic properties in shaping the supramolecular assemblies and solid-state structures. These insights not only advance crystal engineering strategies but also highlight the versatility of hydantoin derivatives as promising building blocks for materials science and pharmaceutical applications.
Figure 1. Chemical structures of the investigated compounds
Bioinformatic discovery of novel collagen-binding aggregation factors in lactic acid bacteria
No full textLactic acid bacteria (LABs) are a unique group of microorganisms found in the diet of nearly
all humans and form an integral part of the healthy human microbiome. Some LAB strains
exhibit a remarkable ability for autoaggregation, mediated by Snowflake Forming Collagen
Binding Aggregation Factors (SFCBAFs)—a fascinating group of proteins described so far
only in LABs. To date, only five SFCBAFs have been characterized in detail: AggL from
Lactococcus lactis, AggE from Enterococcus faecium, AggLb from Lacticaseibacillus paracasei, AggLr from Lactococcus raffinolactis, and AggA from Tetragenococcus halophilus.
In this study, we present bioinformatically predicted novel SFCBAF candidates and demonstrate their widespread distribution among LAB species. Furthermore, we provide evidence
that such proteins may not be exclusive to LABs, as homologous sequences were also identified in phylogenetically distant bacteria such as Staphylococcus aureus, Oceanobacillus
spp., Bacillus spp., and others, expanding our understanding of this unique protein family
Evolucija mikrostrukture pod različitim uslovima homogenizacije i njen uticaj na procese rekristalizacije tokom toplog valjanja legure AA5182
No full textThis study investigates microstructure development of AA5182 Al-Mg alloy under various homogenization conditions and how these conditions affect recrystallization processes and texture development during the laboratory hot-rolling. Homogenization treatments were conducted for 16 h at 490 °C and for 4 h, 16 h and 96 h at 550 °C. Scanning electron microscopy (SEM) characterization including energy-dispersive X-ray spectroscopy (EDX) revealed the presence of Al3(Fe,Mn) and Alm(Fe,Mn) phases as Fe/Mn-bearing microconstituents in the as-cast state. These transformed into Al6(Fe,Mn) and α-Al(Fe,Mn)Si during homogenization treatments. The treatments also led to precipitation of Al6(Mn,Fe) and α-Al(Fe,Mn)Si dispersoid particles. The results of electron backscattered diffraction (EBSD) indicated that a weak deformation texture was present after hot-rolling. The morphology of grains and the degree of restoration were significantly influenced by homogenization conditions. The distribution and density of dispersoids had a strong effect on the mechanisms of recovery and recrystallization.Ova studija ispituje razvoj mikrostrukture legure AA5182 Al–Mg pri različitim uslovima homogenizacije kao i uticaj tih
uslova na procese rekristalizacije i razvoj teksture tokom laboratorijskog toplog valjanja. Homogenizacija je sprovedena u
trajanju od 16 h na 490 °C, kao i u trajanju od 4 h, 16 h i 96 h na 550 °C. Karakterizacija primenom skenirajuće elektronske
mikroskopije (SEM), uključujući energijski disperzivnu rendgensku spektroskopiju (EDX), otkrila je prisustvo faza
Al3(Fe,Mn) i Alm(Fe,Mn) kao mikro-konstituenata koji sadrže Fe/Mn u livenom stanju. Tokom homogenizacije ove faze su
transformisane u Al6(Fe,Mn) i α-Al(Fe,Mn)Si. Različiti tretmani doveli su do izdvajanja disperzoidnih čestica Al6
(Mn,Fe) i
α-Al(Fe,Mn)Si. Rezultati difrakcije povratno rasejanih elektrona (EBSD) ukazali su na prisustvo slabe deformacione
teksture nakon toplog valjanja. Morfologija zrna i stepen restauracije bili su značajno uslovljeni parametrima
homogenizacije. Raspodela i gustina disperzoida snažno su uticale na mehanizme oporavljanja i rekristalizacije
Enhanced separation of valuable compounds from Spirulina using supercritical carbon dioxide: Influence of pretreatments and co-solvent addition on composition and bioactivity of extracts
No full textThere is a lack of information on pretreatments that improve the separation of biologically valuable extracts from Spirulina using supercritical carbon dioxide (scCO2). Therefore, this study was focused on testing microwave irradiation and rapid gas decompression pretreatments for the recovery of Spirulina extracts that express antioxidant, antimicrobial, and cytotoxic activity. Extractions from native and pretreated microalgae were performed using scCO2 at 40 MPa and 40 °C, without or with ethanol as a co-solvent. Results revealed that the extraction process was positively influenced to some extent by the application of each pretreatment and co-solvent addition. Specifically, extraction yield was improved up to 8.7-fold, separation of γ-linolenic acid increased from 7.3% to 35.6 %, chlorophyll A content increased from 12.1 to 272.1 mg/g extract, and tocopherol amount rose from 1.3 to 24.7 mg α-TE/g dry biomass. On the other hand, separations performed with co-solvent decreased the content of carotenoids from 100.2 to 35.6 mg/g as well as the antioxidant activity of extracts and their cytotoxicity on human hypopharyngeal squamous cell carcinoma. Moreover, the addition of ethanol to scCO2 had an adverse effect on the flavonoid content (which ranged from 45.8 to 82.4 mg RE/g) and the antimicrobial activity of extracts against 32 microbial strains. This exploratory study provides guidelines for the design, operation, and intensification of an environmentally friendly separation of added-value Spirulina extracts
Investigation of processing methods for the recovery of gold, copper, and nickel values from RAM connectors
No full textRandom-access memory (RAM) can be a valuable source for metals such as Au, Cu, and Ni. The RAM connectors consist of end contacts (Cu, Ni, Au) and a fber-reinforced Cu laminated structure. The study investigates two process routes involving leaching and pyrolysis (as a pre-or post-treatment). Various parameters (acid concentration, solid–liquid ratio, time, and H2O2 dosage) are evaluated during the direct leaching of connectors (without crushing) using HNO3 and MSA. The optimal parameters are 4M MSA at solid-to-liquid ratio (S/L)- 1/20, at 50 °C for 180 min, resulting in Cu ~57.6% and Ni ~91% dissolution. Further, the Cu powder (98% purity) from the leach solution is recovered by chemical reduction using ascorbic acid. The rest of the Cu present as tracks in RAM strips is recovered by pyrolysis (550 °C, 1h) followed by density separation. Alternatively, pyrolysis is applied as a pre-treatment for organic decomposition and detachment of gold contacts. Subsequently, the gold contacts are leached to dissolve the Cu and Ni values at optimal conditions. However, the dissolution of Ni is hindered due to char formation (in the case of MSA leaching), and the fnal gold residue contains char as an impurity. Leaching followed by pyrolysis leads to 94% of copper (as Cu precipitate and Cu from tracks) and 97% of gold (as gold fngers) recovery in solid form, while nickel is recovered in the leach solution
The role of epithelial-mesenchymal interfacial tension in biological systems
No full textThe interfacial tension between two cell subpopulations in direct contact represents a key physical parameter responsible for the self-organization of tissues during biological processes such as morphogenesis and the spreading of cancers. Higher interfacial tension (i) reduces the spreading of cancer-mesenchymal cells through the epithelial subpopulation, (ii) ensures efficient cell segregation in co-cultured systems, (iii) can induce extrusion of cancer-mesenchymal cells along the biointerface with the epithelial subpopulation, and (iv) results in the generation of higher mechanical stress along the biointerface. Inhomogeneous distribution of the interfacial tension leads to the Marangoni effect, which further facilitates the rearrangement of cells. The formation of mobile stiffness gradients, known as durotaxis, under in vivo conditions is directly related to an inhomogeneous distribution of the interfacial tension. As the product of homotypic and heterotypic cell–cell interactions, the interfacial tension depends on the distance between the subpopulations, which varies over time. This review (i) summarizes biological aspects related to the homotypic and heterotypic cell–cell interactions along the biointerface, together with the viscoelasticity of cell subpopulations caused by collective cell migration and by compression (de-wetting)/extension (wetting) of the subpopulations; and (ii) describes these same biological aspects from a biophysical/mathematical perspective by pointing to the role played by the interfacial tension
Interplay between viscoelasticity and stiffness as essential properties in mechanobiology
No full textOver the last ten years, there has been a significant surge in mechanobiological research aimed at elucidating how substrate stiffness alters cell biology and the stiffness of multicellular systems. Although the concept of ‘stiffness,’ is employed to describe the material characteristics of both cells and their substrates, it lacks a precise definition within the realms of soft matter physics and rheology. Generally, stiffness can be understood as the degree to which a material resists deformation when subjected to a mechanical force. It is well established that both multicellular systems and substrate matrices exhibit viscoelastic behaviour. The stiffness of these viscoelastic systems is not constant; rather, it is influenced by the interplay between energy storage, which tends to increase stiffness, and energy dissipation, which tends to reduce it. These processes can occur simultaneously or at different rates. The traction forces exerted by cells can induce alterations in the substrate matrix, thereby modifying its stiffness, which in turn affects the efficiency of cell migration and the overall stiffness of a multicellular system. The mechanisms through which cells detect variations in the viscoelastic properties of their surroundings are still being explored, and they are influenced by the rates and magnitudes of energy storage and dissipation. This discussion of stiffness is contextualized through the examination of collective migration in epithelial and mesenchymal monolayers on collagen I matrices, drawing on both experimental findings and rheological constitutive models
Versatile role of Bacillus velezensis: Biocontrol of Fusarium poae and wireworms and barley plant growth promotion
No full textThe major losses in cereal production are most commonly caused by phytopathogenic fungi and insect larvae, indicating the need for sustainable pest control management. Although bacterial bioinoculants offer an eco-friendly alternative for plant protection and growth promotion (PGP), their effects on Fusaium poae and Agriotes lineatus larvae have not been comprehensively studied yet. To find an effective biological control agent against these pests, Bacillus strains were isolated from soil and tested for PGP and biocontrol traits, including the presence of antibiotic and toxin-coding genes. Out of eleven strains, B. velezensis BHC 5.6 showed a wide range of PGP and biocontrol abilities, while the presence of fenD, bmyB, srfAA, spaS genes was also detected. Only two strains, P. megaterium BHC 5.5 and B. velezensis BHC 5.6, showed antifungal effect against F. poae with inhibition percentage of 62% and 67%, respectively. The highest insecticidal effect against wireworms was recorded for B. velezensis BHC 5.6 (56.67%) and B. safensis BHC 11.4 (43.33%). The PGP activity of B. velezensis BHC 5.6 was also confirmed in a pot experiment, where an increment of barley yield was recorded both for infected (17.09%) and uninfected barley seeds (10.12%). This is the first time demonstrating that the B. velezensis BHC 5.6 could be used for integrated pest management of F. poae and A. lineatus larvae in barley and for plant growth promoting. Therefore, the implementation of this strain could contribute to the food safety in sustainable agricultural practices
Functionalized composites based on polyvinyl alcohol and activated charcoal for advanced wound application
No full textChronic wounds remain a pressing healthcare challenge, often complicated by microbial colonization and persistent inflammation. To address the growing need for multifunctional wound dressings, this study explores polyvinyl alcohol (PVA) hydrogels combined with activated charcoal (AC), and further functionalized with either silver ions (SI) or povidone-iodine (PI). The aim was to combine moisture retention, antimicrobial efficacy, malodor control, and structural stability in a single material. PVA–AC hydrogels were synthesized through a freezing-thawing method and subsequently loaded with antimicrobial agents via immersion in either 100 or 1000 ppm water solutions. Characterization revealed successful incorporation of both SI and PI onto AC, although only silver-functionalized hydrogels demonstrated significant antimicrobial activity against clinical isolate of Klebsiella pneumoniae, showing a 3–4-fold reduction in bacterial count. PI-functionalized samples, in contrast, failed to release detectable iodine into the simulated wound fluid, likely due to strong adsorption onto AC. Swelling tests showed moderate fluid uptake, with slightly lower values in AC-containing samples. These findings suggest that PVA–AC–SI hydrogels hold promise as effective antimicrobial dressings, while the modular nature of the developed material supports future adaptation with other therapeutic agents