Solvent Water Research Articles

Waterborne superhydrophobic bio-epoxy coating on Al alloy for corrosion-resistant and self-cleaning applications

Aluminum (Al) and its alloys are important engineering materials in modern industry due to their numerous advantages and have been widely used in various fields, including aerospace, marine, civilian industries and so on. However, they are prone to corrosion and contamination under harsh environmental conditions, particularly in marine environment when exposed to salty water or moisture for a long time, which can adversely affect their aesthetic appearance and desired functionalities or even cause economic losses and serious accidents. To prevent or delay the corrosion, the hydrophilic nature of Al and its alloy surfaces can be transformed to be hydrophobic or superhydrophobic. In this study, we reported an environment-friendly waterborne superhydrophobic bio-epoxy coating (WSBC) without using volatile solvents. The coating is composed of bio-epoxy resin, nano silica, silane coupling agent as well as hydrophobic curing agent, and applied by spin method on Al alloy substrates. The surface morphology and roughness were characterized by a field emission scanning electron microscope (FESEM) and an atomic force microscope (AFM). The WSBC with 22.2 wt% nano silica loading without considering the solvent of DI water displays a water contact angle (CA) as high as 165.8 ± 3.3° and a sliding angle (SA) as low as 5.3 ± 2.5°. Electrochemical measurement results showed that the as-prepared WSBC has a significant shift from −1.160 V to −0.708 V in the corrosion potential (Ecorr) and 3 orders of magnitude decrease in the corrosion current density (Jcorr), indicating excellent corrosion resistance. The WSBC was further proven to function well after immersion in deionized (DI) water and common organic solvents including ethanol and acetone for 48 h, and weathering resistance test. In addition, the as-prepared WSBC also showed good self-cleaning performance. The developed coating is green and no harm to human health and environment. The facile and eco-friendly process is of great importance for many industrial applications which can provide an attractive way towards anti-wetting surfaces for corrosion protection and self-cleaning effect on a variety of engineering substrates.

Nanoscale Poly(Dopamine)‐Modified ZIF‐8 Particle Hybrid Solvent‐Resistant Thin Film Nanocomposite (TFN) Membranes via Interfacial Polymerization on a Robust Polyether Ether Ketone (PEEK) Substrate

ABSTRACTThis study introduces an innovative approach to fabricating a poly ether ketone (PEEK)‐based thin‐film nanocomposite (TFN) nanofiltration membrane. Ultrafine polydopamine (PDA) modified zeolitic imidazolate framework‐8 (ZIF‐8) nanoparticles were integrated into the polyamide (PA) layer through a process of interfacial polymerization. The impacts of PDA@ZIF‐8 nanoparticle loading on composite membranes were examined, and their separation performances with different solvents and small molecular organics with various molecular weights and charges were evaluated. The PDA modification is credited with inducing a thinner, less crosslinked PA layer, culminating in the formation of a selective barrier that is both loose and ultra‐thin, improving the separation capabilities of membranes. The TFN‐3 membrane, with a 0.01 wt% loading of PDA@ZIF‐8 nanoparticles, emerged as a standout, demonstrating notably enhanced hydrophilicity. The pure water and organic solvent permeances through the TFN‐3 membrane were remarkably enhanced, with recorded values of 6.19 ± 0.26 L h−1 m−2 bar−1 for pure water and 3.44 ± 0.21 L h−1 m−2 bar−1 for methanol. Furthermore, the TFN‐3 membrane showcased impressive molecular retention in ethanol solutions for compounds with a molecular weight cut‐off (MWCO) of 464 g/mol. The PEEK‐based TFN‐3 membrane also exhibited exceptional creep resistance, ensuring consistent performance during long‐term testing. In a 5‐day ethanol separation test, the TFN‐3 membrane maintained a Rose Bengal (RB) retention rate exceeding 99%, underscoring its stability and reliability. The newly developed PEEK‐based TFN membrane not only promises robust solvent resistance and stability but also delivers efficient separation and purification capabilities. It holds great potential for offering effective and sustainable solutions across a spectrum of industries, particularly in pharmaceutical production and chemical processing, where the separation, recovery, and purification of solvents are paramount.

The Formation Mechanism of Zein Gel Induced by Amyloid-like Fibrils

The preparation of zein gels often leads to unstable product quality due to poor reproducibility, posing substantial challenges for the food industry and biomedical applications. Thus, it is essential to study the gelation mechanism and key factors responsible for gelation. Herein, we report four types of assembled structures from zein solutions in binary ethanol–water solvents with either a high concentration (30% w/v) and a low concentration (5% w/v), namely, spheres, spheres with tangential structures, amyloid-like fibrils, and sub-agglomerates with crystal structures. The tangential structure at the edges of the spheres was first observed by transmission electron microscopy (TEM) at the initial stage, offering a model for studying protein folding and aggregation mechanisms. By observing the gelation processes with TEM for morphology, cryo-TEM to confirm structure preservation, HR-TEM for fine details, and negatively stained TEM to reveal hidden features, along with small-angle X-ray scattering (SAXS), we identified two types of gels: one was mainly network structures formed by sphere–sphere fusion, which was thermoreversible, and the other one was irreversible gel due to the increase in the amount of amyloid-like fibrils. Results show that the existence of thermoreversible zein gels indicates potential effective regulation tools of zein gel properties. In addition, amyloid-like fibrils were first isolated from native zein. During amyloid-like fibril formation, the number of tangential structures increased considerably, which were composed of thinner fibrils. High-resolution TEM showed a substructure with a 0.35 nm interplanar spacing, providing evidence of β-sheet aggregates also as confirmed by SAXS. This unique substructure has not been reported in other edible proteins. Moreover, understanding the fibrillation mechanism of zein provides a basis for controlling and developing novel food structures for food protein function and offers insights into neurodegenerative diseases.

Siamese neem tree as a natural preservative: Chemical profile, antioxidant properties, and antibacterial efficacy against foodborne pathogens and spoilage bacteria

The objective of the present study was to investigate the effect of various ethanol in water solvent systems (0, 25, 50, 75 and 100% v/v) on the extraction crude yield, total phenolic content, total flavonoid content, and chemical profile of Azadirachta indica (Siamese neem tree) leaf extracts. In addition, the antioxidant and antimicrobial properties were investigated using in vitro assays. Crude yield was highest for the water extract (5.78 g/100 g DW) and decreased with increased ethanol. Total phenolic and flavonoid contents were highest in the 75% ethanol extract (26.95 mg GAE/g crude and 23.73 mg QE/g crude, respectively). GC-MS analysis of the 75% ethanol extract revealed 33 bioactive compounds, accounting for 96.33% of the total area. Significant components included benzene, 1,4-bis(phenylmethyl)- (15.05%), and naphthalene, 1,6-dimethyl- (10.98%); also present were sterols, fatty acids, hydrocarbons, aromatic, and heterocyclic compounds, indicating a complex chemical profile. In antioxidant assays, the 75% ethanol extract revealed the highest DPPH radical scavenging activity (IC50: 143.03 mg/L), reducing power (IC50: 378.69 mg/L), and lipid peroxidation (IC50: 526.25 mg/L). However, the absolute ethanol extract exhibited both the highest metal chelating activity (IC50: 382.60 mg/L) and the strongest antimicrobial activity, inhibiting all 11 tested foodborne pathogenic and spoilage bacteria. The lowest minimum inhibitory concentration (MIC) of 25 mg/mL was observed for Staphylococcus aureus, Aeromonas hydrophila, Pseudomonas fluorescens, Latilactobacillus sakei, Streptococcus sp., and Lactococcus cremoris, with inhibition zone diameters of 27.21, 28.79, 28.19, 17.60, 15.09 and 11.20 mm, respectively. Similarly, the lowest minimum bactericidal concentration (MBC) of 25 mg/mL was obtained for S. aureus and L. sakei, indicating potent antibacterial effects against these species. Future studies should include direct comparative analyses of neem extracts and synthetic preservatives to evaluate further their relative efficacy and applicability in real-world food systems.

Synthesis and Characterization of Bis (mercaptoacetamido)-butanediol Dihydrazone Coordination Polymers

Coordination polymers of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd (II) with bis-bidentate ligand delivered from mercaptoacetic acid and 2,3 butanedione dihydrazone have been prepared. All polychelates are coloured, amorphous solid insoluble in water and common organic solvents and characterized with the aid of analytical, magnetic, spectral and thermal studies. The Mn(II),Co(II) and Ni(II) polychelates are of a six co-ordinated octahedral structure, where as Zn(II) and Cd(II) polychelates are found to be four co-ordinated while Cu(II) exhibit square planer structure respectively. Elemental analysis indicators a metal: ligand ratio 1:1 by using graphical Freeman–Carrol method various thermodynamics parameters have also been evaluated. Thermal stability of the complexes have been tested for their antibacterial activity against the bacteria E coli, Bacillus sp, stappylocous and Pseudomonus sp. The solid state conductivity of ligand and complexes were also measured in their compressed pettet from in the temperature range 310-450 K and all complexes were are found to be semiconducting in behaviour.

The effect of infrared-assisted thermal and hydrothermal treatments on low-quality wheat flour obtained from tail-end passages and cracker quality

Low-quality wheat flour (LQF) is a by-product with high nutritional value but poor shelf life and technological properties. In this study, infrared (IR)-assisted thermal and hydrothermal treatments were applied to stabilize LQF and improve its functional properties. For the hydrothermal treatments, LQF was adjusted to 15%, 20%, 25%, and 30% moisture content. Samples were processed at 800 W IR emitter power until moisture content dropped below 8%.While the treatments had little effect on the core composition of the flour, they led to an increase in its maximum, final, and setback viscosities. Thermal treatment increased water absorption and solvent retention capacity, shortened dough development time (DDT), and did not affect extensibility. Hydrothermal treatments, however, led to an increase in extension resistance and DDT. The 15% initial moisture content improved dough stability and extensibility, but these characteristics declined at higher moisture levels.In crackers produced from the treated flours, increasing initial moisture levels improved the spread ratio, though moisture levels of 25–30% reduced hardness and created a brittle texture. These findings revealed that varying initial moisture levels allowed for selective modifications in the stabilization of LQF, with acceptable changes in color and composition.

Impact of Na-Carboxymethyl Cellulose Binder Type on Hard Carbon Performance and SEI Formation in Sodium-Ion Batteries.

The development of hard carbon (HC) electrodes using biobased binders, formulated in water solvent, is of great interest for Na-ion batteries. Five Na-carboxymethyl cellulose (CMC) binders with different molecular weights and degrees of substitution were investigated. The increase in the CMC molecular weight led to an increase in the volume of water necessary for slurry preparation and a decrease in the electrode mass loading. Moreover, the adhesion of the slurry was strongly impacted by the aluminum current collector properties. A high initial Coulombic efficiency, iCE (up to ∼90%), and reversible capacity (up to 334 mAh g-1 at C/10) were obtained in Na half-cells. Post-mortem XPS analyses performed on several electrodes under various conditions allowed a better understanding of the formation and composition of the solid electrolyte interphase (SEI) layer. The genesis of SEI was initially chemically driven: to a small extent, by HC and to a greater extent, by the Na metal. However, SEI formation was mainly governed by the electrochemical-driven degradation of the electrolyte salt and solvent. The SEI layer composed of an inorganic-rich core and an organic-rich shell significantly decreased the resistance of the HC electrode, allowing superior iCE while maintaining high capacity retention (96.2%), after 100 cycles at 1C.

Preparation and Characterization of Poly(acrylic acid-co-vinyl imidazole) Hydrogel-Supported Palladium Catalyst for Tsuji–Trost and Suzuki Reactions in Aqueous Media

In this study, a novel polyacrylate-co-vinyl imidazole hydrogel-supported palladium (Pd) catalyst (P(AA-co-VI)@Pd) was prepared through heat-initiated polymerization, starting with the formation of a complex between vinyl imidazole and palladium chloride, followed by the addition of 75% neutralized acrylic acid (AA), crosslinking agent, and initiator. The structure and morphology of the catalyst were characterized using ICP-OES, SEM, EDX, Mapping, FT-IR, TGA, XRD, XPS and TEM techniques. It was confirmed that the catalyst exhibited excellent compatibility with water solvent and uniform distribution of Pd. The P(AA-co-VI)@Pd hydrogel catalyst demonstrated remarkable catalytic activity and ease of separation. Notably, in a Tsuji–Trost reaction, employing water as the solvent, it achieved a conversion rate as high as 94% at very low catalyst dosages, indicating its superior catalytic performance. Moreover, after six consecutive cycles, the catalyst maintained good activity and structural stability, highlighting its exceptional reusability and environmental friendliness. Furthermore, the outstanding efficiency of the catalyst was also observed in a Suzuki coupling reaction where both conversion rate and yield reached 100% and 99%, respectively, within just one hour reaction time, thus further validating its universality and efficacy across various chemical reactions.

Influences of Coagulant Polarity on the Modulus of the Chitin Hydrogel.

The chitin hydrogel draws great attention in biomedical fields owing to its high similarity and good affinity for peptides. The conversion of raw chitin to the designed hydrogel through a sol-gel process prevails, while the modulus of the chitin hydrogel is significantly influenced by the factors of gelation technology (i.e., coagulation, involving polymer chain rearrangement and the reconstruction of multiple interactions). Water and several organic solvents such as ethanol, DMAc, and DMSO are effective coagulants for aqueous chitin/KOH/urea solutions. In particular, the concentration of aqueous ethanol solutions displays a high dependency on the modulus of chitin hydrogels. However, recent reports about chitin hydrogel fabrication seldom demonstrate the effect of coagulant factors on hydrogel performance. Our study found that the polarity of the coagulant and its diffusion index for entry into the chitin solution during the coagulation process had a direct influence on the hydrogel modulus. The influence of the two factors was investigated to find out their quantified relationship with the hydrogel modulus, which will inspire a practical method to develop new coagulants to prepare modulus-manipulable chitin hydrogels.

Toward nanosuspension preparation by modeling the solubility of levofloxacin and ofloxacin in ethanol + water solvent mixtures at different temperatures

The present study was conducted to assess the solubility of levofloxacin and ofloxacin in different mono- and mixed solvent systems at different temperatures to provide an experimental basis for the preparation of levofloxacin and ofloxacin nanosuspensions. To this end, the solubility of both compounds was evaluated using a solid–liquid equilibrium technique in DMSO, acetone, ethanol, NMP, and water monosolvents and ethanol–water mixed solvents at different volume fractions and temperatures. The modified versions of the van’t Hoff and Gibbs equations were recruited to calculate the thermodynamic properties of the solutions. The correlation between the solubility data of levofloxacin and ofloxacin and different mathematical models, including the Yalkowsky, Jouyban-Acree, and van’t Hoff models and their combinations was studied. According to the results, the highest and lowest solubility of levofloxacin and ofloxacin were attainable in 1 (pure ethanol monosolvent) and 0.1 v/v of ethanol fractions in ethanol/water mixed solvent. Moreover, the solubility of both compounds was superior at higher temperatures. Afterwards, the nanosuspensions were prepared using the solvent-antisolvent method. Different characterization techniques revealed the formation of the smallest particles with relatively irregular morphology in the 0.1 v/v volume fraction of ethanol in water. The XRD analysis exhibited the typical crystalline diffractions of levofloxacin and ofloxacin and the thermal transitions and stability of both compounds were investigated using DSC and TGA techniques. The results obtained in this study could be used to enhance the solubility and bioavailability of levofloxacin and ofloxacin during the drug formulation development and manufacturing processes.

Determination of pKa Values of C-H Bonds in Polar Fluorinated Arenes Referred to a New CF3SO2-Substituted Anchor Compound.

pKa values of C-H bonds remain unreported and challenging in fluorous solvents because of these solvents' unique physicochemical properties, although they have been measured, theorized and predicted successfully in water and common organic solvents. Herein, a new CF3SO2-substituted anchor compound designed for matching the physicochemical properties of polar fluorinated arenes is synthesized. Its self-dissociation constants in these solvents are used as bases for experimentally determining the pKa values of 36 C-H compounds in them. These experimentally determined pKa values exhibit excellent linear free-energy relationships and correlate well with their corresponding DFT-calculated values. These data indicate that the polar fluorinated arenes are thermodynamically more favorable for deprotonation of ketone derivatives than acetonitrile as reaction media, resulting in enhanced deprotonation-promoted CO2 fixation. The pKa values determined in this work can be used as an important guidance tool for reactions involving the formation and cleavage of C-H bonds in polar fluorinated arenes.

Mechanics-Switchable and Antiswelling Colloidal Hydrogels Inspired by the Cononsolvency Effect.

Stiffness switching hydrogels have been in high demand for intelligent devices, adhesion science, soft robotics, and flexible electronics. However, it is challenging to post-tune the mechanical properties of a hydrogel once the polymer network structure is formed. Inspired by the cononsolvency effect, we prepared a mechanics-switching colloidal hydrogel through the precipitation polymerization of methacrylamide in mixed dimethyl sulfoxide and water solvents. The colloidal network enables the hydrogels to simultaneously strengthen, stiffen, and toughen. The colloidal hydrogels not only display a broad spectrum of adjustable mechanical properties (ranging from 0.08 to 57.1 MPa) via solvent response but also accomplish reversible stiffness conversion through the solvent-tuned conformational adjustment of colloidal polymer networks, with the maximum modulus conversion reaching 1427, and exhibit solvent-responsive shape memory. Based on the stable and tight colloidal network, the hydrogels exhibit antiswelling properties in various aqueous solutions and solvents. The colloidal hydrogel would provide more possibilities in various applications, such as antiimpact protection, shape memory, electronic switches, and intelligent engineering materials. It is envisioned that this work will provide key opportunities in developing mechanics-switching and on-demand tuning of soft materials for tissue engineering, flexible electronics, and biomedical science.

Lagrangian formulation of nuclear-electronic orbital Ehrenfest dynamics with real-time TDDFT for extended periodic systems.

We present a Lagrangian-based implementation of Ehrenfest dynamics with nuclear-electronic orbital (NEO) theory and real-time time-dependent density functional theory for extended periodic systems. In addition to a quantum dynamical treatment of electrons and selected protons, this approach allows for the classical movement of all other nuclei to be taken into account in simulations of condensed matter systems. Furthermore, we introduce a Lagrangian formulation for the traveling proton basis approach and propose new schemes to enhance its application for extended periodic systems. Validation and proof-of-principle applications are performed on electronically excited proton transfer in the o-hydroxybenzaldehyde molecule with explicit solvating water molecules. These simulations demonstrate the importance of solvation dynamics and a quantum treatment of transferring protons. This work broadens the applicability of the NEO Ehrenfest dynamics approach for studying complex heterogeneous systems in the condensed phase.

Appraisal of surface-active properties and micellization behaviour of imidazolium gemini surfactants

ABSTRACT A series of imidazolium gemini surfactants with three different hydrophobic chains have been synthesised and analysed by 1HNMR, 13CNMR, FTIR, ESI-MS and TGA. The conductivity of these surfactants has been taken at 293, 298, 303 and 308 K in water, and results have indicated that these gemini surfactants act as weak electrolytes. Thermodynamic properties calculated from conductance have confirmed that micellization was spontaneous and more favourable in comparison to dissociation process. Density as well as viscosity measurements were indicating that there exist significant interactions between these gemini surfactants and solvent (water) molecules. Surface active properties have confirmed that imidazolium gemini surfactants are excellent candidates to lower the surface tension at air/water interface and having affinity to form aggregates in the bulk solution after CMC. Thermogravimetric analysis (TGA) has indicated that all the three surfactants have thermal stability up to 535–600 °C. The thermal stability was increasing with increasing hydrophobic chain, and the activation energy for thermal decomposition was found in the range of 20.43–36.55 kJ/mol. Moreover, antimicrobial activities were examined and inferred that these compounds exhibit excellent antimicrobial activity against B. cereus and C. albicans.

Computational Characterization of the DAD Photoisomerization: Functionalization, Protonation, and Solvation Effects.

Photoswitches are becoming increasingly popular in pharmacology due to the possibility of modifying their activity with light. Hence, it is crucial to understand the photophysics of these compounds to identify promising light-activated drugs. We focused our study on DAD, an azobenzene derivative that, according to a previous experimental investigation, can restore visual function in blind mice due to trans-cis photoisomerization upon light absorption. With the present computational study, we aim to characterize the absorption spectrum of DAD, and to understand its photoisomerization mechanism by means of conformational search analysis, quantum mechanical (QM) and hybrid QM/continuum calculations, and classical molecular dynamics simulations. Moreover, we explored the effect of the derivation (DAD vs azobenzene), the protonation (DAD vs DADH22+, the two possible protonation states) and the solvation (vacuum vs water) on the photoisomerization. Similarly to azobenzene, we showed that the photoisomerization of both protonation states of DAD begin with the population of the bright S2 state. Then, it crosses to the S1 surface and relaxes along the rotation of the azo dihedral to a S1/S0 crossing point. The latter is close to a transition state that connects the trans and cis geometries on the ground state. Finally, our results suggested that amino derivation, nonprotonation and water solvation could improve the quantum yield of the photoisomerization.

Reduction of 4‐Nitrophenol Catalyzed by Gold Nanoclusters with Aggregation‐Induced‐Emission: Emission Intensity Correlated Activity and Mechanistic Exploration

AbstractThiolate‐protected Au nanoclusters (NCs) have developed as a promising class of model catalysts to achieve fundamental understanding of metal nanocatalysis. Whereas, the packing mode of peripheral ligand on metal core is changeful in the reaction medium and show elusive impact on catalytic activity. In this work, using glutathione (GSH) protected Au NCs (Au@GSH NCs) with aggregation‐induced‐emission (AIE) characteristics as model catalyst for the hydrogenation of 4‐nitrophenol (4‐NP), photoluminescence (PL) intensity correlated catalytic activity of Au@GSH NCs was successfully mediated by the addition of Ag+ in the preparation or poor solvent in the reaction medium, showing a relationship of “as one falls, another rises.” Au NCs with intense PL implied a dense packing of peripheral ligand, which hampered the accessibility of active site and thus exhibited slowest catalytic reaction kinetics of the reduction of 4‐NP and vice versa. Based on this methodology, a case study of the effect of salt additives on the catalytic activity is carried out, different mechanisms are distinguished by the change in the PL intensity, and with the combination of diagnostic deuterium isotope experiments, it has been demonstrated that the proton from water solvent is involved in the reaction and that the proton transfer process is the rate‐determining step, the contribution of ionic additives to the hydrogen bonding network determines their effect on the reaction kinetics. The correlation between PL intensity and catalytic activity of Au NCs could provide an efficient way to design highly active Au NC catalysts and give a new insight to understand the unique optoelectronic properties of Au NCs and reaction mechanism.

Combining the Powerful Antioxidant and Antimicrobial Activities of Pomegranate Waste Extracts with Whey Protein Coating-Forming Ability for Food Preservation Strategies.

Different solvents water, ethanol and ethanol/water (6:4 v/v), were compared in the extraction of pomegranate peels and seeds (PPS) in terms of recovery yields, antioxidant properties, and antimicrobial action against typical spoilage bacterial and fungal species. The best performing extract (ethanol/water (6:4 v/v) was shown to contain mostly ellagic acid and punicalagin as phenolic compounds (5% overall) and hydrolysable tannins (16% as ellagic acid equivalents) and was able to inhibit the growth of the acidophilic Alicyclobacillus acidoterrestris at a concentration as low as 1%. The preservation of the organoleptic profile of A. acidoterrestris-inoculated apple juice with extract at 1% over 20 days was also observed thanks to the complete inhibition of bacterial growth, while the extract at 0.1% warranted a significant (40%) inhibition of the enzymatic browning of apple smoothies over the first 30 min. When incorporated in whey proteins' isolate (WPI) at 5% w/w, the hydroalcoholic extract conferred well appreciable antioxidant properties to the resulting coating-forming hydrogel, comparable to those expected for the pure extract considering the amount present. The WPI coatings loaded with the hydroalcoholic extract at 5% were able to delay the browning of cut fruit by ca. 33% against a 22% inhibition observed with the sole WPI. In addition, the functionalized coating showed an inhibition of lipid peroxidation of Gouda cheese 2-fold higher with respect to that observed with WPI alone. These results open good perspectives toward sustainable food preservation strategies, highlighting the potential of PPS extract for the implementation of WPI-based active packaging.

A computational study of the size effect of SiO2 spherical nanoparticles in water solvent.

This study comprehensively describes the interaction between SiO2 spherical nanoparticles and water molecules as a solvent medium. Our goal is to provide valuable insights into the significance of nanoparticle size in understanding their behavior and the resulting changes in the physical properties of materials. Our results indicate that SiO2 nanoparticles exhibit a strong affinity for water, which increases with the nanoparticle size. Our investigation can be relevant for the design of new composite materials with applications ranging from medical prostheses to quantum electronics, optoelectronic devices, catalysis, and photoluminescence. We have concentrated on the study of the amorphous, where size effects seem to be more pronounced. A computational study was carried out within the molecular dynamics simulations framework available in the GROMACS-v2019.2 software, with force fields consistent with DFTand the CHARMM36 utilized in the molecular description of the systems. The water model used was the TIP3P implemented in CHARMM36 force fields. A comprehensive analysis of molecular interactions of various system configurations was performed, including radial distribution function (RDF), mean square displacement (RMSD), hydrogen bonding analysis,interfacial analysis, andstudying system size'seffect on mechanical properties.

Computational Study on the Octahedral Surfaces of Magnetite Nanoparticles and Their Solvent Interaction.

Magnetite nanoparticles (MNPs) play an important role in geological and environmental systems because of their redox reactivity and ability to sequester a wide range of metals and metalloids. X-ray absorption spectroscopy conducted at metal and metalloid edges has suggested that the magnetite {111} faces of octahedrally shaped nanoparticles play a dominant role in the redox and sorption processes of these elements. However, studies directly probing the magnetite surfaces, especially in their fully solvated state, are scarce. Therefore, we investigated the speciation and stability over a wide Eh/pH range of octahedrally shaped MNPs of 2 nm size by means of Kohn-Sham density functional theory with Hubbard correction (DFT+U). By altering the protonation state of the crystals, a redox-sensitive response of the octahedrally coordinated Fe could be achieved. Furthermore, the preferential H distribution could be identified, highlighting the difference between the edges, vertices, and facets of the nanocrystals. Subsequently, the interactions of the MNPs with a solvent of pure water or a 0.5 M NaCl solution were studied by classical molecular dynamics (MD) simulations. Finally, a comparison of the corresponding macroscopic magnetite (111) surface to the investigated MNPs was conducted.

Superacid-Synthesized Fluorinated Diamines Act as Selective hCA IV Inhibitors.

Carbonic anhydrase (CA) IV is a membrane-bound enzyme involved in important physio-pathological processes, such as excitation-contraction coupling in heart muscle, central nervous system (CNS) extracellular buffering, and mediation of inflammatory response after stroke. Known since the mid-1980s, this isoform is still largely unexplored when compared to other isoforms, mostly for the current lack of inhibitors targeting selectively this isoform. The discovery of selective CA IV inhibitors is thus largely awaited. In this work, we report β-(di) fluoropropyl diamines as effective CA IV inhibitors, opening real perspectives for a new mode of selective inhibition of this isoform. Inhibition data reveal that the essential structure core to ensure a potent and selective inhibition of CA IV is the N-propyldiamine. Molecular modeling studies were employed to understand the binding mode of the synthesized amines. Conformational searches within the active site space carried out in an implicit solvent (water) model were also conducted.