Properties Of Aqueous Solutions Research Articles

Effect of Chirality and Amphiphilicity on the Antimicrobial Activity of Tripodal Lysine-Based Peptides.

A series of tripodal (three-arm) lysine-based peptides were designed and synthesized and their self-assembly properties in aqueous solution and antimicrobial activity were investigated. We compare the behaviors of homochiral tripodal peptides (KKY)3K and a homologue containing the bulky aromatic fluorenylmethoxycarbonyl (Fmoc) group Fmoc-(KKY)3K, and heterochiral analogues containing k (d-Lys), (kkY)3K and Fmoc-(kkY)3K. The molecular conformation and self-assembly in aqueous solutions were probed using various spectroscopic techniques, along with small-angle X-ray scattering (SAXS) and cryogenic-transmission electron microscopy (cryo-TEM). In cell viability assays using fibroblast cell lines, the tripodal peptides without Fmoc were observed to be noncytotoxic over the concentration range studied, and the Fmoc functionalized tripodal peptides were only cytotoxic at the highest concentrations (above the critical aggregation concentration of the lipopeptides). The molecules also show good hemocompatibility at sufficiently low concentration, and antimicrobial activity was assessed via MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) assays. These revealed that the Fmoc-functionalized tripodal peptides had significant activity against both Gram-negative and Gram-positive bacteria, and in the case of Gram-positive Staphylococcus aureus, the antimicrobial activity for Fmoc-(kkY)3K was improved compared to polymyxin B. The mechanism of the antimicrobial assay was found to involve rupture of the bacterial membrane as evident from fluorescence microscopy live/dead cell assays, and scanning electron microscopy images.

Supramolecular phosphorescent assemblies based on cucurbit[8]uril and bromophenylpyridine derivatives for dazomet recognition.

A bromophenylpyridine derivative (N1) was designed, synthesized, and the molecule was incorporated into the cavity of the cucurbit[8]uril (Q[8]) as a guest to form a 2:1 host-guest complex. This complex demonstrates good room temperature phosphorescence (RTP) properties in aqueous solution. The host-guest interaction and optical properties of N1@Q[8] in aqueous solution were studied by means of 1H NMR, ultraviolet-visible absorption spectroscopy, fluorescence spectroscopy, phosphorescence spectroscopy, scanning electron microscopy and inverted fluorescence microscopy. The results show that the bromophenyl part of the guest molecule enters the cavity of Q[8], while the other part of N1 remains outside the cavity, resulting in a 2:1 supramolecular structure. This assembly exhibits specific recognition of dazomet on the phosphorescence spectrum with a detection limit of 8.8329×10-7mol·L-1. Collectively, this finding opens up a new possibility for the potential application of room temperature phosphorescent materials in analytical detection.

A case report on ulcer healing properties of aqueous solution of geranium maculatum mother tincture in chronic neuropathic ulcer of foot

A case report on ulcer healing properties of aqueous solution of geranium maculatum mother tincture in chronic neuropathic ulcer of foot

Volumetric properties of aqueous solutions of small monohydric alcohols. Molecular dynamics simulation

Volumetric properties of aqueous solutions of small monohydric alcohols. Molecular dynamics simulation

Polymercationic Drilling Fluids for Well Construction in Challenging Mining and Geological Conditions

Background: Oil and gas well drilling involves the use water- and hydrocarbon-based drilling fluids for flushing. While hydrocarbon solutions offer several advantages—such as preventing rock softening on the wellbore walls, reducing the formation of caverns due to instability in clay rocks, and dissoving salts (like halite, sylvinite, and bischofite), and preserving the natural reservoir properties of productive formations—they also have significant drawbacks. These disadvantages are related to the properties of the dispersion medium, which limits their overall application. The dispersion medium in hydrocarbon solutions consist of compounds that are both environmentally and flammable, such as kerosene, diesel fuel, olefins, various oils, etc. Increasing concern from government and environmental organizations regarding the environmental impact of drilling fluids using hydrocarbon dispersion medium have promted the industry to focus on water-based solutions. Despite several significant disadvantages, water-based drilling fluids are still more in demand than hydrocarbon ones. Although there is a preference for hydrocarbon systems, approximately 85% of all drilling fluids used worldwide today are water-based. This study focuses on a new approach in the field of water-based drilling fluids: the development, creation and implementation of polymer cationic systems. The idea of developing new water systems involves creatng polymer cationic working fluids that combine the beneficial properties of hydrocarbon and aqueous solutions. Aim: To research and develop modern polymer cationic drilling fluids for well construction in the Republic of Kazakhstan. Materials and methods: Polymer cationic drilling fluids were selected as the objects of study. To address the research objectives, experiments were conducted under both laboratory and field conditions. Results: This article presents the findings of laboratory tests and field trials conducted in the fields of the Russian Federation and the Republic of Kazakhstan. Conclusion: For the first time in global practice, stable polymer cationic drilling fluids have been developed and successfully tested, combining the advantages of aqueous and hydrocarbon systems. Both theoretical and practical principles for managing the properties of polymer cationic solutions have been established. The application of modified polymer cationic drilling fluids in well construction at the at the Astrakhan field and the Uzen field has demonstrated their high performance. This innovation has enabled the prevention of production isuues, increased mechanical speed of drilling, improved wellbore condition, reduced cavern porosity, and successfully completed the construction of over 20 wells. Additionally, it facilitated implementation of high-density solutions for killing brine and other related tasks.

Non-Contact Interaction Between Phorbol Myristate Acetate and Aqueous Alcohol Solutions Under Combined Magnetic Fields.

Previous research has demonstrated that a combined magnetic field (CMF) plays a critical role in modifying the properties of aqueous solutions, leading to an increase in the luminol-enhanced chemiluminescence of neutrophils. Using this model, the distant interaction between aqueous solutions was demonstrated, and the role of a CMF in the regulation of this phenomenon was established. In the current study, highly diluted (HD) phorbol myristate acetate (PMA) solution (the donor) was incubated with aqueous ethanol (the acceptor), both in a CMF-generating device and under geomagnetic field (GMF), for 0, 20, and 60 min. After a 60 min incubation at a 0 cm distance with HD PMA under both GMF and CMF, acceptor samples added to neutrophils increased neutrophil chemiluminescence by approximately sevenfold. The ability of HD PMA, which had been incubated with an acceptor, to activate ROS production diminished within 60 min of observation. However, the HD PMA sample remained an effective donor for up to 6 days after preparation. At a 10 cm distance between the donor and acceptor, the activation of the acceptor did not occur. These findings provide new insights into the phenomenon of distant interaction of solutions, whose mechanisms are suggested to be related to the quantum electrodynamics of water molecular dynamic structures.

Supercritical density fluctuations and structural heterogeneity in supercooled water-glycerol microdroplets

Recent experiments and theoretical studies strongly indicate that water exhibits a liquid-liquid phase transition (LLPT) in the supercooled domain. An open question is how the LLPT of water can affect the properties of aqueous solutions. Here, we study the structural and thermodynamic properties of supercooled glycerol-water microdroplets at dilute conditions (χg = 3.2% glycerol mole fraction). The combination of rapid evaporative cooling with femtosecond X-ray scattering allows us to outrun crystallization and gain access to the deeply supercooled regime down to T = 229.3 K. We find that the density fluctuations of the glycerol-water solution or, equivalently, its isothermal compressibility, κT, increases upon cooling. This is confirmed by molecular dynamics simulations, which indicate that the presence of glycerol shifts the temperature of maximum κT from T = 230 K in pure water down to T = 223 K in the solution. Our findings elucidate the interplay between the complex behavior of water, including its LLPT, and the properties of aqueous solutions at low temperatures, which can have practical consequences in cryogenic biological applications and cryopreservation techniques.

Conceptual Model of Digitization of the Municipal Wastewater Disposal Systems

In the modern world, intelligent and digital wastewater disposal systems are increasingly in demand for real-time decision-making on the environmental efficiency of wastewater disposal. The aim of the study is to develop wastewater management processes for monitoring and predicting the parameters of sewerage networks. This paper presents the results of physical modeling of changes in the properties of aqueous solutions transported through the sewerage network to the treatment plant. It was found that the quality of wastewater without additional pollutants is stable, but under the influence of complex, disturbing factors, significant fluctuations in parameters are observed, requiring preventive control to prevent secondary pollution. In order to eliminate the disadvantages of prototypes and improve the environmental safety of wastewater disposal, a conceptual model of digitalization of the wastewater disposal system of water supply and sewerage facilities in the segment “Transport—wastewater treatment” based on the criteria of environmental efficiency of treatment facilities was justified and created. This model for regulating wastewater discharge parameters considers the quality indicators of domestic and industrial wastewater, which excite technological processes at municipal wastewater treatment plants and makes corrections through local treatment methods. This will reduce the risk of secondary pollution and increase management efficiency and environmental compliance of treatment facilities but, at the same time, requires significant investment, infrastructure modernization, qualified personnel and solutions to the issues of integrating processes into a single system. Also, a conceptual scheme of monitoring and forecasting sewerage network parameters and the sequence of sewerage system digitalization using the example of a settlement was created. Further research will be aimed at building a digital system of regulation of water supply and sewerage facilities in the segment based on the criterion of the ecological efficiency of treatment facilities with regard to disturbance.

Effect of Iodide Ion Concentration on the Physicochemical Properties of Aqueous Sodium Phosphate Solutions as Fertilizer

Effect of Iodide Ion Concentration on the Physicochemical Properties of Aqueous Sodium Phosphate Solutions as Fertilizer

Nanoarchitectonics of SiO2 composite hydrogel in inorganic solution: Simulation and experimental analysis

Polyacrylamide hydrogels are widely used in medicine, petrochemical, water treatment and other fields, among which polyacrylamide hydrogels play an important role in oilfield Profile control and water shutoff and enhanced oil recovery, however, there are few reports on the effect of different inorganic salt solutions on the properties of SiO2 composite hydrogel. In this paper, a cross-linked SiO2 composite hydrogel was constructed using Materials Studio software for the first time, and its structure and properties in inorganic salt aqueous solutions were studied. The results show that the addition of inorganic salts can weaken the interaction between water molecules and hydrogels, and this effect is minimal in calcium chloride solution. The radial distribution function shows that there are strong hydrogen bonds between nitrogen and oxygen atoms in the amide group and water molecules, but there are van der Waals forces between oxygen and water atoms, and the addition of inorganic salts will enhance the hydration of nitrogen atoms in the amide group and the interaction between monovalent ions and amide groups was greater than that between bivalent ions. At the same time, the addition of inorganic salts can also enhance the diffusion ability of water molecules and the fluidity of polymer chains. Among the four inorganic salt solutions, Calcium chloride solution has the least effect on the polymer chain and the cross-linked SiO2 composite hydrogel has the best expansion performance in calcium chloride solution, which is basically consistent with the experimental results, this has a potential application prospect in the reservoir with high calcium content for profile control and water plugging and enhanced oil recovery.

BiVO4-Based Chloride Oxidation for Hypochlorous Acid (HOCl) Production, and Analysis of the Causes of Saturation Phenomenon

Hypochlorous acid (HOCl) is commonly used in antibacterial and disinfection treatments due to its strong oxidizing properties in aqueous solutions. Chlor-alkali process, an electrolysis method based on sodium chloride (NaCl), is the primary method for producing HOCl in industry. However, this process incurs significant energy costs, approximately 150 TWh annually, and presents dangers of environmental pollution. To address these issues and achieve environmental and economic benefits, reducing energy consumption in HOCl production using renewable energy sources such as solar power is proposed as a viable solution. Various metal oxides like TiO2, WO3, and BiVO4 have been utilized in photocatalytic systems. Among these, BiVO4 photocathodes, with a bandgap energy of around 2.4 eV, efficiently absorb a significant portion of visible light spectrum, enabling effective oxygen generation from water. However, the low value of generated oxygen (O2) prompts the development of novel photocatalytic systems from a product value perspective. Chloride oxidation reactions, instead of water oxidation, present another promising avenue in photocatalytic systems.In this study, we easily fabricate BiVO4 electrodes via spin-coating method. We investigate the synthesis of high-value chemicals by using the oxidation of Cl- to hypochlorous acid at the anode in electrolytes containing Cl-, such as sodium chloride (NaCl) solution. Furthermore, saturation phenomena were observed during the oxidation of sodium chloride to hypochlorous acid; when the oxidation reaction persisted for over an hour, the production of hypochlorous acid reached saturation, indicating no further increase. We aim to identify and analyze the fundamental causes of this phenomenon to understand the limiting factors in this process.AcknowledgementsThis work was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program-Alchemist Project) (NTIS-1415187362, 20025773, Development of building-Integrated Carbon Control Technologies) funded By the Ministry of Trade, Industry & Energy(MOTIE, Korea)This work is financially supported by Korea Water Cluster (KWC) as Korea Water Cluster ProjectLab

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.

Efficient Removal of Cationic Dye by Biomimetic Amorphous Calcium Carbonate: Behavior and Mechanisms.

The search for efficient, environmentally friendly adsorbents is critical for purifying dye wastewater. In this study, we produced a first-of-its-kind effective biomimetic amorphous calcium carbonate (BACC) using bacterial processes and evaluated its capacity to adsorb a hazardous organic cationic dye-methylene blue (MB). BACC can adsorb a maximum of 494.86 mg/g of MB, and this excellent adsorption performance was maintained during different solution temperature (10-55 °C) and broad pH (3-12) conditions. The favorable adsorption characteristics of BACC can be attributable to its hydrophobic property, porosity, electronegativity, and perfect dispersity in aqueous solution. During adsorption, MB can form Cl-Ca, S-O, N-Ca, and H-bonds on the surface of BACC. Since BACC has excellent resistance to adsorption interference in different water bodies and in real dye wastewater, and can also be effectively recycled six times, our study is an important step forward in dye wastewater treatment applications.

Effect of Pyrrolidinium Based Ionic Liquid on Thermo Physical and Electrochemical Properties of Binary Aqueous Solutions of Benzylamine and Benzamide at Different Equidistant Temperatures (288.15 K to 318.15 K)

Effect of Pyrrolidinium Based Ionic Liquid on Thermo Physical and Electrochemical Properties of Binary Aqueous Solutions of Benzylamine and Benzamide at Different Equidistant Temperatures (288.15 K to 318.15 K)

Enhanced hydrolysis of MgH₂ by transition metal oxides and NaH: Performance, mechanisms, and optimization

MgH₂ is recognized as a promising material for hydrogen production due to its high hydrogen density, abundant availability, and non-polluting hydrolysis by-products, making it a viable hydrogen source for fuel cells. This study, for the first time, investigates the hydrogen production performance of the MgH₂-MOx-NaH (M = Ti, Zr, Mo, Fe, V, Bi) system, which exhibits remarkable hydrolysis properties in aqueous solutions. A series of MgH₂-MOx-NaH composite powders were synthesized via mechanical ball milling. The results revealed that V₂O₅-NaH and Bi₂O₃-NaH significantly enhanced the hydrolysis performance of MgH₂ for hydrogen production. Specifically, Bi₂O₃-NaH and V₂O₅-NaH effectively refined MgH₂ particles and mitigated agglomeration during the milling process. Hydrolysis tests demonstrated that the conversion rate and the hydrogen generation rate (mHGR) of composites initially increased with ball milling time and then decreased. The maximum hydrolysis hydrogen production yield and conversion rate for MgH₂-Bi₂O₃-NaH and MgH₂-V₂O₅-NaH composites occurred at a ball milling duration of 10 hours, and reached up to 1354.1 mL g⁻¹ (88.5 %) and 1273.5 mL g⁻¹ (81.8 %), respectively, within 8 minutes. Kinetic tests of hydrolysis hydrogen production showed that the reaction rate and hydrogen conversion increased with elevated hydrolysis temperatures. The activation energies for the hydrolysis of MgH₂-MOx-NaH (M = Ti, Zr, Mo, Fe, V, Bi) were calculated from the hydrolysis-hydrogen production curves using the Arrhenius formula, yielding values of 41.32, 37.66, 36.40, 34.60, 30.80, and 27.17 kJ mol⁻¹, respectively. The lower activation energies for hydrolysis indicate improved reaction kinetics, suggesting that the incorporation of transition metal oxides and sodium hydride effectively enhances both the hydrolytic conversion and reaction rate of MgH₂.

Molecular diffusion in aqueous methanol solutions: The combined influence of hydrogen bonding and hydrophobic ends.

Although the nonmonotonic variation in the diffusion coefficients of alcohol and water with changing alcohol concentrations in aqueous solutions has been reported for many years, the underlying physical mechanisms remain unclear. Using molecular dynamics simulations, we investigated the molecular diffusion mechanisms in aqueous methanol solutions. Our findings reveal that the molecular diffusion is co-influenced by hydrogen bonding and the hydrophobic ends of methanol molecules. A stronger hydrogen bond (HB) network and a higher concentration of hydrophobic ends of methanol molecules both enhance molecular correlations, thereby slowing molecular diffusion in the solution. As methanol concentration increases, the HB network weakens, facilitating molecular diffusion. However, the increased concentration of hydrophobic ends counteracts this effect. Consequently, the diffusion coefficients of water and methanol molecules exhibit nonmonotonic changes. Previous studies have only focused on the role of HB networks. For the first time, we have identified the impact of the hydrophobic ends of alcohol on molecular diffusion in aqueous alcohol solutions. Our research contributes to a better understanding and manipulation of the properties of aqueous alcohol solutions and even liquids with complex compositions.

Development of oat malt production technology using plasma-chemically activated aqueous solutions

The object of the study was oat malt production. The result of the presented study is the development of a technology for gluten-free oat malt production using cold plasma-treated technological solutions. The material for the study was oat grain. The main technological task is to obtain high-quality oat malt, which, in turn, will be suitable for producing gluten-free beverages and highly nutritious foods. The expediency of using cold plasma-treated aqueous solutions as an activator of the oat malting process and an effective disinfectant of the technological process and the finished product (oat malt) was experimentally proved. It was confirmed that using cold plasma-treated aqueous solutions can accelerate the oat germination process: the germination energy increased by 6–14 %; germination capacity by 2–10 %. The moisture content of oats when moistened increases by 6–37 %. Analysis of the amylolytic enzymatic activity showed a dynamic increase of 17.6 %. The result was the breakdown of carbohydrates. Thus, the amount of starch decreased by 2.4 %, fiber did not undergo significant changes, and the content of simple sugars increased by 2.3 %. The proteolytic activity of oat malt increased by 18.1 %. An increase in the amount of amino acids in the experimental samples was noted. The total amount of amino acids is 793 mg/100 g of product higher than in the control (i.e. by 3 %). There was also an increase in the content of vitamins B (B1, B2), as well as vitamin C, the content of which increased by 5.6 %. Disinfecting properties of cold plasma-treated aqueous solutions in relation to oat malt were noted. The innovative technology of oat malt production can be implemented in the industrial production of gluten-free malts for the brewing industry and for producing gluten-free foods.

Diluting humic substances in water in molecular dynamics simulations: Are aggregates stable?

Natural organic matter (NOM) and humic substances (HS) as its part are key players in diverse biogeochemical processes occurring at interfaces at different scales, contributing to the carbon cycling, sorption reactions, transport and environmental fate of chemicals and biological activity. One important vision considers HS composed of small molecules interacting through non-covalent forces rather than representing high-molecular-weight substances. There is a continued interest in understanding the structure of NOM/HS and modeling their physico-chemical characteristics using molecular simulations. This work aimed to examine the stability of HS models, represented as aggregates formed by small molecules, upon dilution in water, by performing molecular dynamics (MD) simulations. The HS models were built to reproduce a 13C NMR-derived composition of standard Leonardite humic acid (HA) by using the Vienna Soil Organic Matter Modeler. The models varied in molecular size, amount of water and the choice of counter cation (Na+ vs Ca2+), while keeping the chemical composition identical, to link low-hydrated HS systems with aqueous NOM solutions in the concentration range of environmental significance. MD simulations demonstrated that HS aggregates disintegrate to some degree by diluting the system. The process occurs more easily in the presence of monovalent Na+ compared to divalent Ca2+. Strong interactions within the HS aggregates may remain at the level of dimers of small molecules revealing a higher stability against dilution. The simulation results support a step-wise mode of HS aggregation. It is suggested also that the existence of large-size HS molecules possibly undergoing step-wise aggregation should be taken into account while examining HS properties in aqueous solutions.

ДОСЛІДЖЕННЯ АДСОРБЦІЇ CrО42- ТА Cr2О72- ПОЛІАНІЛІНОМ ІЗ ВОДНИХ РОЗЧИНІВ

The optical properties of aqueous solutions of chromate CrО42- and dichromate Cr2О72- ions were studied. Optical spectra were used to study the adsorption of chromate CrО42- and dichromate Cr2О72- ions by a sample of polyaniline (PAn) from aqueous solutions of different concentrations. It was established that the removal and adsorption of CrО42- and Cr2О72- by the PAn sample depends on the concentration of oxyanions in the initial solutions. Adsorption studies of PAn sample with respect to oxyanions CrО42- and Cr2О72- were carried out from solutions with concentrations of 50, 100, 150, 200 and 250 mg/L. Examination of the samples after the adsorption tests revealed that the polyaniline sample retains adsorbed chromium, apparently in the Cr(III) state. The analysis of SEM-images, EDX-spectra and maps of elements proves that the distribution of adsorbed chromium is practically uniform over the surface of the adsorbent, and the intensity of its signal on the elemental maps depends on the initial concentrations of solutions of oxyanions CrО42- and Cr2О72-. Examination of the PAn sample using SEM-EDX spectra before and after adsorption revealed that the morphologies of the samples differ. The analysis of the EDX spectra of the elemental composition of the samples after adsorption of CrО42- and Cr2О72- confirmed that they contain, in addition to the PAn elements, also chromium. The distribution of chemical elements in the samples after adsorption revealed that they are almost uniformly distributed surfaces, and the intensity of its signal on EDX spectra depends on the initial concentrations of oxyanion solutions CrО42- and Cr2О72-. The value of CrО42- adsorption by the PAn sample is almost twice as small as the value of Cr2О72- adsorption. By comparing the contents of atoms of elements, in particular sulfur (S) and oxygen (O), before and after adsorption, it was found that S is replaced by Cr, and the content of O slightly increases with an increase in the initial concentration of Cr(VI) in the solutions.

Martini 3D-OZ: A Theoretical Investigation of Solvation Shell Structures and Solvation Free Energies of Martini Coarse-Grained Proteins.

We investigate the properties of aqueous solutions using integral equation theories and molecular dynamics (MD) simulations within the framework of the MARTINI coarse-grained force field. The integral equation theory used in the present work is based on the Ornstein-Zernike equation coupled with the hypernetted chain (HNC) and Kovalenko-Hirata (KH) closures. Overall, the solvation shell structures and solvation thermodynamics in the HNC approximation are shown to be in better agreement with those from the MD simulation than the KH results. Especially, through the analysis of spatial distribution functions of water around a protein, we have demonstrated that the HNC approximation can provide the highly anisotropic structure of the solvation shell of the protein. On the other hand, the KH approximation works well for simple particle solutes, but the results for highly hydrated proteins deviate quite significantly from the MD results. We further explore in detail the reason underlying the deviation caused by the KH approximation. Lastly, a potential application of the integral equation theory with the MARTINI model is outlined.