ACS Physical Chemistry Au最新文献

This work proposes the use of Coffee Silver Skin, a by-product of coffee production, as an adsorbent substrate for the removal of the antibiotic Norfloxacin from water and assesses the possibility of regenerating it through advanced oxidation processes. In detail, the study was developed by showing the best conditions for the pollutant removal, in which the adsorption process occurred with the main involvement of electrostatic interactions. A preliminary desorption approach in the presence of salt-based solutions, i.e., NaCl and 0.1 M MgCl₂, was followed with the aim of desorbing the non-photodegraded Norfloxacin from the regenerated adsorbent. Therefore, indirectly, the quantitative evaluation of photodestroyed Norfloxacin was assessed according to selected working conditions: UV light, UV light/H₂O₂, UV light/TiO₂, and UV light/TiO₂/H₂O₂. Moreover, a comparison with the literature devoted to Norfloxacin photodegradation directly in water was accomplished. The use of UV light/TiO₂ occurred as the best approach for the purpose of obtaining the complete degradation of Norfloxacin in 6 h. On the other hand, the use of H₂O₂ did not improve the process. Thus, to reduce the irradiation time, Norfloxacin degradation was evaluated simultaneously during its release from the adsorbent, in a 0.1 M MgCl₂ solution, retrieving a similar and well-known behavior observed when the pollutant was degraded in water. In 3 h, the desorbed Norfloxacin was destroyed, enabling the recycling of Coffee Silver Skin for up to 3 cycles.

This work investigates the molecular dynamics of the peptide nanofiber E₂(SW)₆E₂, a biomolecule/structure in an aqueous solution, characterized by hydrophilic and hydrophobic contrasts. Through classical molecular dynamics simulations, the study examines the energetic, structural, and dynamic properties of this nanofiber, with a focus on energetic and hydrogen bond (HB) interactions between peptides and peptide-water. Simulations of different fiber lengths indicate that larger models exhibit increased structural stability and longer HB lifetimes, contributing to enhanced fiber flexibility and integrity. Additionally, the analysis of the mass density profile along the nanofiber length reveals local decreases (but not zero) in mass density. The results further emphasize the potential of these structures for applications in ion and drug transport due to their hydrophobic core and hydrophilic surface. This work provides a comprehensive understanding of molecular interactions in self-assembled bionanomaterials in aqueous solutions.

Solution-based single-molecule conductance measurements of α,ω-bis-(carboxylic acids) are conveniently performed using a high-boiling-point nonconducting ethereal solvent. First-principles calculations support experimental observations that linear oligoalkanes exhibit the expected exponential decay of conductance with length, whereas junctions comprising cyclic bridge hydrocarbons of different lengths and/or structures exhibit a similar conductance.

Ionic liquids (ILs) have been widely used as alternative solvents for the stabilization, storage, and extraction of DNA. However, studies on the interaction between ammonium-based ILs and DNA, particularly focusing on the effect of anions, remain limited. Tetrabutylammonium (TBA) cation-based ILs with propanoate, bromide, glutamate, and threoninate anions were used to analyze IL–DNA interactions through UV–vis titrations, steady-state and time-resolved fluorescence, and molecular docking. The conformational stability and thermal stability of DNA in IL solutions were analyzed through circular dichroism spectroscopy and UV thermal studies, respectively. Viscosity measurements of the IL solutions were carried out to support the data obtained from UV thermal studies. The TBA cation displays multiple modes of interaction at the groove through electrostatic, hydrophobic, and hydrogen bonding. Among the studied anions, the propanoate anion exhibits significant hydrophobic interactions in addition to hydrogen bonding, whereas glutamate and threoninate primarily engage in hydrogen bonding. The difference in the effect of the ILs on DNA underscores the significant influence of the anions on IL–DNA interactions.

Intrinsically disordered proteins (IDPs) perform diverse biological functions without adopting stable folded structures, instead existing as dynamic ensembles of flexible conformations. While these conformations were traditionally attributed to weak, nonspecific interactions, emerging evidence emphasizes the role of transient, specific interactions. Here, we investigate how charged amino acids within IDP sequences influence the prevalence of these interactions. Using model peptides, we establish an empirical relationship between the fraction of transient interactions and a novel sequence metric, the effective charge patch length. Extending this analysis to IDP ensembles with varying levels of transient interactions, we uncover heteropolymeric structural behaviors, including network formation in phase-separated condensates. A large-scale analysis reveals that approximately 20% of disordered regions in the human proteome exhibit charge-driven transient interactions, contributing to heteropolymeric conformational ensembles. Finally, we explore the functional enrichment of these interactions, underscoring their potential role in mediating diverse biological processes.

Sodium-ion batteries are emerging as a cost-effective and sustainable alternative to the lithium-ion technology. Prussian blue compounds are demonstrating considerable potential as cathode materials, offering exceptional structural stability and rapid sodium-ion diffusion capabilities. However, in spite of the importance of Prussian Blue for the emerging technology of sodium-ion batteries, surprisingly many atomistic details of the structural changes upon charging and dis-charging are not yet clarified. This study aims to assess stable sodium configurations and derive reliable site occupancy statistics. We employ periodic density functional theory (DFT) to construct the first complete convex hull for the cubic system, encompassing all 24d sites, thereby exploring the entire configurational space available within these compounds. We identify a new, more stable sodium arrangement within the fully sodiated, cubic Prussian Blue structure, which has to be considered for reliable atomistic modeling. The convex hull identifies a single stable intermediate sodium concentration (x = 1), which aligns with observed voltage plateaus in open-circuit voltage measurements. Furthermore, a comparative analysis of the cubic phase and its rhombohedral counterpart is conducted, demonstrating qualitative consistency with phase transition for higher sodium concentrations (x > 1). These results strengthen the evidence that Prussian Blue compounds offer exceptional potential as cathode materials, providing valuable insights into their intricate sodium orderings.