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In this study, a comparison of biofilm formation, extracellular polymeric substances (EPS) production, protein and polysaccharides estimation, and protein profiling through SDS-PAGE, FTIR, GC-MS, ESI-MS, SEM, and AFM analysis were done for EPS from epilithic bacteria Brevundimonas faecalis BC1 obtained from monumental rock under normal room temperature and heat stressed condition. Heat stress (60 ± 2 °C) that simulates hot monumental rock surfaces during the summer season caused bacteria BC1 to produce more EPS (8.56 g/L), biofilm, protein and polysaccharides, extra SDS-PAGE protein bands of different molecular weight than their control counterpart. FTIR and GC-MS analysis showed extra polysaccharide formation in the EPS under heat stress and ESI-MS analysis clearly showed differences in structural components of EPS from two different sources. Consistently, SEM and AFM showed more branching structural components with dentate spikes in the EPS obtained from a heat-stressed source than from its counterpart, suggesting their protective role toward heat stress and adhesive potential for biofilm. [ABSTRACT FROM AUTHOR]

Nowadays, miniaturization of high-performance electronic devices leads to higher heat generation, which needs efficient cooling to maintain device temperature below its operating temperature. This work proposed an efficient cooling technique using two-phase flow boiling in a recharging microchannel (RMC) and compared its performance with the conventional simple microchannel (SMC). A three-dimensional numerical investigation is carried out using the volume-of-fluid multiphase model and evaporation–condensation phase-change model in ANSYS Fluent V15. Water with mass fluxes of 100 and 500 kg/(m2·s) enters through the microchannel at inlet subcooling of 5 °C, whereas the substrate bottom surface is subjected to constant heat flux in the range of 10–40 W/cm2. The water saturation temperature is considered as 50 °C, corresponding to the saturation pressure of 12.352 kPa. Results reveal that the RMC shows enhanced heat transfer coefficient, reduced thermal resistance, reduced wall superheat, and reduced substrate temperature compared to SMC. Besides, the RMC shows a reduced pressure drop than the SMC at lower mass flux, whereas it shows an increased pressure drop at higher mass flux. The flow boiling instabilities can mitigate during the bubbly flow regime in RMC. This study suggests the possible application of flow boiling in RMC to cool high-performance electronic devices. [ABSTRACT FROM AUTHOR]

Background: Antimicrobial resistance has become a serious concern and threat to global health. This has triggered the need for the design of new antimicrobials. In this study, poly‐ionic liquid (PIL) homopolymers have been designed by varying the alkyl chain lengths to evaluate their pathogeneses against Gram‐positive (Staphylococcus aureus) and Gram‐negative bacteria (Escherichia coli). Results: The results demonstrated that the antimicrobial and antibiofilm activities depend on the alkyl chain length of PILs (C10 > C8 > C6). To support the experimental findings, in silico analyses were performed to explore the structural and functional information of bacterial RNA polymerase (RNAP) enzymes. A switch region was identified between RNAP β subunit (RpoB) and RNAP β' subunit (RpoC) with 1119 amino acids (aa) and 1504 (2–1505) aa, respectively. The docking analysis reflected the docking energies −5.313 kcal mol−1 for RNAP‐poly‐1‐vinyl‐3‐hexyl imidazolium complex, −4.634 kcal mol−1 for RNAP‐poly‐1‐vinyl‐3‐octyl imidazolium complex, and −3.456 kcal mol−1 for RNAP‐poly‐1‐vinyl‐3‐decyl imidazolium complex. Conclusion: The synthesized PIL samples exhibited antibacterial and antibiofilm activities against E. coli and S. aureus. However, the effect on E. coli was more prominent in comparison to S. aureus. The results indicated that both electrostatic interaction and hydrophobic effect played a vital role in enhancing the antibacterial as well as antibiofilm activities. In addition, in silico analysis identified the 'switch region' between RNAP β subunit (RpoB) and RNAP β subunit (RpoC). The novel target appeared to be a binding region for PILs and restricted the synthesis of bacterial RNA. It can be concluded that imidazolium‐based PILs can be used as safe antibacterial materials in the healthcare sector. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

In recent years, bacterial infection has become one of the significant clinical challenges. The overuse or misuse of antibiotics increases the number of antibiotic‐resistant bacterial pathogens and causes enormous medical burdens with high morbidity and mortality. Several strategies have been adopted to tackle this; poly‐ionic liquids (PILs), a class of ionic liquids (ILs) systems demonstrating a broad spectrum of antimicrobial activities, have been widely used in biomedical applications. During polymerization, the charge density of the cations, molecular weight, and hydrophobic behavior can be regulated to accomplish more potent antibacterial efficacy with low cytotoxicity. However, inadequate literature is available highlighting the application of PIL‐based materials in biomedical applications. Keeping this in mind, the recent advances in PIL‐based biomaterials formed by conjugating PIL with natural and synthetic polymers as effective antimicrobial agents have been the focus area of this review. [ABSTRACT FROM AUTHOR]

The study reports the density (ρ), molar volume (V), partial molar volume (Vm1)/(Vm2) and refractive index (nD) of the binary mixture of 2‐methylimidazole and 1‐butanol/octanol at T=300.15–318.15 K. The accuracy of the experimental results was checked with different refractive mixing models like Lorentz‐Lorentz (L−L), Arago‐Biot (A−B), Gladstone‐Dale (G−D), Newton (N), Heller (H) and Wiener (W) and the root mean square deviation have also been presented.. The excess values were fitted to Redlich‐Kister polynomial equation and the standard deviations were also calculated. The negative VE and ΔnD values at higher mole fraction of 2‐methylimidazole indicate specific interaction between the unlike components due to hydrogen bonding but with rise in temperature the bonds tend to dissociate leading to restricted associations. Density functional theory has also been used to investigate the effective reactivity between 2‐methylimidazole and 1‐butanol/1‐octanol. The difference between ELUMO and EHOMO ranged from −12.9 to 16.523 kcal/mol. 2‐methylimidazole‐1‐octanol displayed greatest reactivity with lowest band energy gap. [ABSTRACT FROM AUTHOR]

In this study 1-vinyl-3-alkyl imidazolium-based ionic liquid monomers (ILs) with different alkyl chain lengths {R = hexyl (A), octyl (B) and decyl (C)} have been synthesized for antibacterial applications. The prepared ILs have been characterized using UV, FT-IR and NMR spectroscopy. The antibacterial activities of the synthesized ILs against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) have been examined by measuring their minimal inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). The results exhibit that these ILs have admirable antibacterial activities with MIC values range from < 1.2 to 12.2 μM for S. aureus and < 2.4 to 12.2 μM for E. coli. A notable dependence of antibacterial and antibiofilm efficacy on the alkyl chain length (ILC> ILB > ILA) has been observed. From in-silico evaluation, the binding energies of β-lactamase protein of S. aureus (PDB ID: 1GHP) are found to be -4.4, -4.6, -4.7 kcal/mol for IL A, IL B, and IL C. For dihydrofolate reductase (DHFR) of S. aureus and E. coli the binding energies -4.6, -4.5, -5.3 kcal/mol and -5.3, -5.4, -5.6 kcal/mol have been noted for IL A, IL B, and IL C respectively. MD simulations (100 ns) have been performed to predict the stability and understand the binding mechanism of the docked complexes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare that there is no conflict of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)