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We establish the connection between the measured small angle x-ray scattering signal and the charge–charge correlations underlying Kirkwood transitions (KTs) in 1:1, 2:1, and 3:1 aqueous electrolytes. These measurements allow us to obtain underscreening lengths for bulk electrolytes independently verified by theory and simulations. Furthermore, we generalize the concept of KTs beyond those theoretically predicted for 1:1 electrolytes, which involves the inverse screening length, a0, and the inverse periodicity length, Q0. Above the KTs, we find a universal scaling of a 0 ∝ c − ζ / 3 and Q0 ∝ c1/3 for the studied electrolyte solutions, where ζ is the ionic strength factor. [ABSTRACT FROM AUTHOR]

We investigated the effect of the NaCl concentration (0.3–2M) on the structure and dynamics of hen egg yolk at room temperature and during thermal gelation at temperatures in the range of 66–90 °C utilizing low-dose x-ray photon correlation spectroscopy in ultra-small angle x-ray scattering geometry. With an increase in the salt concentration, we observe progressive structural and dynamic changes at room temperature, indicating the disruption of yolk components such as yolk-granules and yolk-plasma proteins. Temperature- and salt-dependent structural and dynamic investigations suggest a delay in the gel formation and aggregation of yolk low-density lipoproteins with increasing ionic strength. However, the time–temperature superposition relationship observed in all samples suggests an identical mechanism underlying protein aggregation–gelation with a temperature-dependent reaction rate. The sol–gel transition time extracted from kinetic and dynamic information follows Arrhenius's behavior, and the activation energy (460 kJ/mol) is found to be independent of the salt concentration. [ABSTRACT FROM AUTHOR]

Surface-specific nonlinear optical techniques are ideally suited to investigate the complex structure of aqueous interfaces. For colloidal particles dispersed in aqueous solutions, interfacial properties can be retrieved with angle-resolved second harmonic scattering (AR-SHS). The mathematical framework of AR-SHS does not require a priori knowledge on the electrostatic distribution in the first few nanometers close to the interface, therefore allowing us to formulate a molecular-level description of the electrical double layer (EDL) based on the experimental data. However, farther away from the interface, an analytical form of the electrostatic potential decay is necessary to account for the distance dependence of the surface electrostatic field propagating into the solution. This requirement is especially important at low ionic strengths, where the electrostatic field is not efficiently screened by counterions. Here, we examine to what extent the analytical form of the electrostatic potential decay impacts the AR-SHS data analysis. We analyze the effect of different functions on the scattering form factors, on the integrated AR-SHS signal intensity, and on the surface parameters extracted from fitting the AR-SHS data. We find that the trends of the surface parameters remain similar regardless of the chosen function, demonstrating the robustness of our approach to establish a molecular-level picture of the EDL. At ionic strengths <10−4M for 100-nm diameter particles, a functional form that physically represents counterions packed more densely in the vicinity of the surface than in the case of the Poisson–Boltzmann distribution has the largest impact, resulting in an overestimation of the obtained surface potential. [ABSTRACT FROM AUTHOR]

Langmuir monolayers of fatty aniline (C16-aniline) were investigated using sum-frequency vibrational spectroscopy at various pH levels and NaCl concentrations. To analyze the sum-frequency generation (SFG) spectra of aniline, a multi-peak Lorentzian model, in accordance with the theory of SFG for a charged interface, was applied. First, SFG spectra of C16-aniline from pH 2 to 6 at a constant ionic strength of 10 mM (where the phase of the complex potential of the dc-induced signal was suppressed to a few degrees) were fitted with the above-mentioned method. The mean-field theory that considers the chemical equilibrium of the aniline headgroup was used to analyze the fitting results to find that the pKa of aniline is 4.4 ± 0.3. The protonation fraction of the aniline headgroup was estimated to be less than 5% at pH 6 and NaCl concentrations were up to 1M. The generalized Poisson–Boltzmann equation in the Gouy–Chapmann model effectively explained the observed SFG spectra in the OH region for fatty aniline at pH as low as 2, even for the systems without addition of any salt. [ABSTRACT FROM AUTHOR]

Charge-stabilized colloidal suspensions display a rich variety of microstructural and thermodynamic properties, which are determined by electro-steric interactions between all ionic species. The large size asymmetry between molecular-scale microions and colloidal macroions allows the microion degrees of freedom to be integrated out, leading to an effective one-component model of microion-dressed colloidal quasi-particles. For highly charged colloids with strong macroion–microion correlations, nonlinear effects can be incorporated into effective interactions by means of charge renormalization methods. Here, we compare and partially extend several practical mean-field methods of calculating renormalized colloidal interaction parameters, including effective charges and screening constants, as functions of concentration and ionic strength. Within the one-component description, we compute structural and thermodynamic properties from the effective interactions and assess the accuracy of the different methods by comparing predictions with elaborate primitive-model simulations [P. Linse, J. Chem. Phys. 113, 4359 (2000)]. We also compare various prescriptions for the osmotic pressure of suspensions in Donnan equilibrium with a salt ion reservoir and analyze instances where the macroion effective charge becomes larger than the bare one. The methods assessed include single-center cell, jellium, and multi-center mean-field theories. The strengths and weaknesses of the various methods are critically assessed, with the aim of guiding optimal and accurate implementations. [ABSTRACT FROM AUTHOR]

Nonlinear optical methods, such as vibrational sum frequency generation (vSFG) and second harmonic generation (SHG), are powerful techniques to study elusive structures at charged buried interfaces. However, for the separation and determination of the Stern and diffuse layer spectra at these charged interfaces, complex vSFG spectra and, hence, the absolute phase need to be retrieved. The maximum entropy method is a useful tool for the retrieval of complex spectra from the intensity spectra; however, one caveat is that an understanding of the error phase is required. Here, for the first time, we provide a physically motivated understanding of the error phase. Determining the error phase from simulated spectra of oscillators with a spectral overlap, we show that for broadband vSFG spectra, such as for the silica/water interface, the diffuse and Stern layers' spectral overlap within the O–H stretching window results in a correlation between the error phase and the phase shift between the responses of these layers. This correlation makes the error phase sensitive to changes in Debye length from varying the ionic strength among other variations at the interface. Furthermore, the change in the magnitude of the error phase can be related to the absolute SHG phase, permitting the use of an error phase model that can utilize the SHG phase to predict the error phase and, hence, the complex vSFG spectra. Finally, we highlight limitations of this model for vSFG spectra with a poor overlap between the diffuse and Stern layer spectra (silica/HOD in D2O system). [ABSTRACT FROM AUTHOR]

We present a simulation method that allows us to calculate the titration curves for systems undergoing protonation/deprotonation reactions—such as charged colloidal suspensions with acidic/basic surface groups, polyelectrolytes, polyampholytes, and proteins. The new approach allows us to simultaneously obtain titration curves both for systems in contact with salt and acid reservoir (semi-grand canonical ensemble) and for isolated suspensions (canonical ensemble). To treat the electrostatic interactions, we present a new method based on Ewald summation—which accounts for the existence of both Bethe and Donnan potentials within the simulation cell. We show that the Donnan potential dramatically affects the pH of a suspension. Counterintuitively, we find that in suspensions with a large volume fraction of nanoparticles and low ionic strength, the number of deprotonated groups can be 100% larger in an isolated system, compared to a system connected to a reservoir by a semi-permeable membrane—both systems being at exactly the same pH. [ABSTRACT FROM AUTHOR]

A clever approach for biosensing is to leverage the concept of the proximity effect, where analyte binding to probes can be coupled to a second, controlled binding event such as short DNA strands. This analyte-dependent effect has been exploited in various sensors with optical or electrochemical readouts. Electrochemical proximity assays (ECPA) are more amenable to miniaturization and adaptation to the point-of-care, yet ECPA has been generally targeted toward protein sensing with antibody-oligonucleotide probes. Antibodies themselves are also important as biomarkers, since they are produced in bodily fluids in response to various diseases or infections, often in low amounts. In this work, by using antigen-DNA conjugates, we targeted an ECPA method for antibody sensing and showed that the assay performance can be greatly enhanced using flexible spacers in the DNA conjugates. After adding flexible polyethylene glycol (PEG) spacers at two distinct positions, the spacers ultimately increased the antibody-dependent current by a factor of 4.0 without significant background increases, similar to our recent work using thermofluorimetric analysis (TFA). The optimized ECPA was applied to anti-digoxigenin antibody quantification at concentrations ranging over two orders of magnitude, from the limit of detection of 300 pM up to 50 nM. The assay was functional in 90% human serum, where increased ionic strength was used to counteract double-layer repulsion effects at the electrode. This flexible-probe ECPA methodology should be useful for sensing other antibodies in the future with high sensitivity, and the mechanism for signal improvement with probe flexibility may be applicable to other DNA-based electrochemical sensor platforms. [ABSTRACT FROM AUTHOR]

This work describes the development of temperature-induced dispersive solid phase extraction (TI-DSPE) for the isolation and measurement of cobalt in food and water samples. The concentration of the preconcentrated cobalt ions was determined using flame atomic absorption spectrometry (FAAS). In TI-DSPE, the dispersion of the sorbent occurs by varying the temperature. The cobalt was complexed with 1-nitroso-2-naphthol and extracted with finely dispersed benzoic acid particles at 60 °C. The extraction efficiencies parameters were assessed and optimized, such as the mass of benzoic acid, dissolution temperature, solution pH, centrifugation conditions, and ionic strength. In the optimum conditions, the analytical curve was linear from 2.0 to 150.0 µg L−1, the limits of detection and quantification were 0.55 and 1.83 µg L−1 respectively, and the preconcentration factor was 50. Ten repeated measurements at 50.0 µg L−1 yielded a relative standard deviation (RSD) of 2.6% (n = 10). High extraction recoveries (96.5–102.5%) were obtained from the analysis of real samples. The validity of the developed procedure was confirmed by analyses of certified reference materials (QC-1187 and SPS-SW2). The results demonstrated that the developed method was simple, efficient, and cost-effective. [ABSTRACT FROM AUTHOR]

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Natural polysaccharides can serve as carriers of genes owing to their intrinsic biocompatibility, biodegradability, and low toxicity. Additionally, they can be easily chemically modified, e.g., through grafting, leading to hybrid synthetic–biological copolymers with additional functionalities. In this work we report on the electrostatic interaction between a chitosan-g-poly(N-isopropylacrylamide) (Chit-g-PNIPAM) copolymer and DNA macromolecules of different lengths (i.e., 50 and 2000 bp), towards the construction of polyplexes that can serve as potential gene delivery systems. At the basic science level, the work aims to elucidate the effects of DNA length on the structural and physicochemical properties of the thermoresponsive hybrid macromolecular assemblies. The protonated amino groups on the chitosan backbone enable electrostatic binding with the anionic phosphate groups of the DNA molecules, while the PNIPAM side chains are expected to impart thermoresponsive properties to the formed polyplexes. Different amino to phosphate group (N/P) mixing ratios were examined, aiming to produce stable dispersions. The physicochemical properties of the resulting polyplexes were investigated by dynamic and electrophoretic light scattering (DLS and ELS), while their morphology was studied by scanning-transmission electron microscopy (STEM). Moreover, their response to changes in temperature and ionic strength, as well as their stability against biological media, was also examined. Finally, the binding affinity of the copolymer towards DNA was evaluated through fluorescence spectroscopy, using ethidium bromide quenching assays, while infrared spectroscopy was used to investigate the structure of the incorporated DNA chains. [ABSTRACT FROM AUTHOR]

Nanochitin was developed to effectively utilize crab shells, a food waste product, and there is ongoing research into its applications. Short nanowhiskers were produced by sonicating partially deacetylated nanochitin in water, resulting in a significant decrease in viscosity due to reduced entanglement of the nanowhiskers. These nanowhiskers self-assembled into a multilayered film through an evaporation technique. The macro- and nanoscale structures within the film manipulate light, producing vibrant and durable structural colors. The dried cast film exhibited green and purple stripes extending from the center to the edge formed by interference effects from the multilayer structure and thickness variations. Preserving structural colors requires maintaining a low ionic strength in the dispersion, as a higher ionic strength reduces electrostatic repulsion between nanofibers, increasing viscosity and potentially leading to the fading of color. This material's sensitivity to environmental changes, combined with chitin's biocompatibility, makes it well-suited for food sensors, wherein it can visually indicate freshness or spoilage. Furthermore, chitin's stable and non-toxic properties offer a sustainable alternative to traditional dyes in cosmetics, delivering vivid and long-lasting color. [ABSTRACT FROM AUTHOR]

We study the high-frequency, micro-mechanical response of suspensions composed of cardiac and skeletal muscle myosin by optical trapping interferometry. We observe that in low ionic strength solutions, upon the addition of magnesium adenosine triphosphate (MgATP2−), myosin suspensions radically change their micro-mechanics properties, generating a viscoelastic fluid characterized by a complex modulus similar to a suspension of worm-like micelles. This transduction of energy, from chemical to mechanical, may be related to the relaxed states of myosin, which regulate muscle contractility and can be involved in the etiology of many myopathies. Within an analogous generic mechanical response, cardiac and skeletal myosin suspensions provide different stress relaxation times, elastic modulus values, and characteristic lengths. These discrepancies probably rely on the dissimilar physiological functions of cardiac and skeletal muscle, on the different MgATPase hydrolysis rates of cardiac and skeletal myosins, and on the observed distinct cooperative behavior of their myosin heads in the super-relaxed state. In vitro studies like these allow us to understand the foundations of muscle cell mechanics on the micro-scale, and may contribute to the engineering of biological materials whose micro-mechanics can be activated by energy regulators. [ABSTRACT FROM AUTHOR]

In recent years, the growing problem of antibiotic resistance has highlighted the need for antibacterial materials to prevent the development of infections. Different types of tests exist to certify the antibacterial properties of materials. Variations in results can occur due to the unique requirements of each test technique. The antibacterial test result may be influenced, in particular, by the distinct modes of action of leaching and non‐leaching compounds. Using antibacterial materials prepared by the dispersion of an amphiphilic cationic synthetic copolymer in a polyurethane matrix, the influence of the reaction medium and the contact time on the results obtained by two well‐established tests: ISO 22196 and CERTIKA is investigated. This shows that the kinetics of killing is bacteria dependent and depending on the test conditions (concentration of salt, time of contact, or media), contradictory results could be obtained. Moreover, the influence of the ionic strength (called salt effect) in both free solution and antibacterial surface is highlighted. [ABSTRACT FROM AUTHOR]

A theoretical approach is presented to quantify the effect of ionic strength on the swelling and shrinkage of the hydrodynamic coil size of a generic biopolymer. This was conducted in view of extraction methods that often utilize acids and alkali combinations and, therefore, invariably impact the levels of salt found in commercially available biopolymers. This approach is supplemented by intrinsic viscosity measurements for the purpose of validation across a variety of biopolymer architectures, type of functionalization, as well as the quoted molar mass. By accurately capturing the magnitude of change in the coil size, it is discussed how a biopolymer coil size is far more sensitive to changes in the ionic strength than it is to the molar mass (or contour length) itself. In turn, it is highlighted why the current characterization strategies that make use of weight-averaged molar mass are prone to errors and cannot be used to establish structure—property relationships for biopolymers. As an alternative, the scope of developing an accurate understanding of coil sizes due to changes in the "soft" interactions is proposed, and it is recommended to use the coil size itself to highlight the underlying structure—property relationships. [ABSTRACT FROM AUTHOR]

More than half of the global population is unable to consume dairy products due to lactose intolerance (hypolactasia). Current enzyme replacement therapy methods are insufficiently effective as a therapeutic approach to treating lactose intolerance. The encapsulation of β-galactosidase in polyelectrolyte microcapsules by using the layer-by-layer method could be a possible solution to this problem. In this study, adsorption and co-precipitation methods were employed for encapsulating β-galactosidase in polyelectrolyte microcapsules composed of (polyallylamine /polystyrene sulphonate)₃. As a result, the co-precipitation method was chosen for β-galactosidase encapsulation. The adsorption method permits to encapsulate six times less enzyme compared with the co-precipitation method; the β-galactosidase encapsulated via the co-precipitation method released no more than 20% of the initially encapsulated enzyme in pH 2 or 1 M NaCl solutions. In contrast, when using the sorption method, about 100% of the initially encapsulated enzyme was released from the microcapsules under the conditions described above. The co-precipitation method effectively prevents the complete loss of enzyme activity after 2 h of incubation in a solution with pH 2 while also alleviating the adverse effects of ionic strength. Consequently, the encapsulated form of β-galactosidase shows promise as a potential therapeutic agent for enzyme replacement therapy in the treatment of hypolactasia. [ABSTRACT FROM AUTHOR]

Mutual separation of trans-plutonium actinides (Ans) from lanthanides (Lns) or adjacent Ans is challenging as they exhibit great chemical similarity. Selective Am oxidation-based Am–Lns or Am–Cm separation strategies give very high separation factors. There exist several reports on different aspects of Am3+ oxidation by NaBiO3·xH2O (x = 2–3), which suggests that the oxidation mechanism is still not well understood. We, therefore, carefully performed several experiments taking advantage of the difference in the redox chemistry of Eu3+ and Am3+. The ion exchange of Eu3+ with the interlayer Na+ in NaBiO3 was confirmed by an ionic strength variation experiment. The shift in the 001 peak of NaBiO3 in XRD and the appearance of peaks corresponding to the trivalent Ln ions in XRF after Ln3+ loading give direct evidence for Na+ exchange with Ln3+. The stability of the higher oxidation state of Am was monitored spectrophotometrically. The experimental investigations also suggested the role of Am3+ → AmO22+ transformation in NaBiO3·xH2O (x = 2–3) dissolution even at pH ∼ 1, which otherwise is difficult to achieve even with >1 M HNO3. The role of colloidal NaBiO3 particles and dissolved BiO3− in controlling or stabilizing different oxidation states of Am was also discussed. [ABSTRACT FROM AUTHOR]

Lactoferrin, lysozyme, and gelatin are three common basic proteins known for their ability to interact with acidic proteins (lactoglobulin, ovalbumin, casein, etc.) and form various supramolecular structures. Their basic nature makes them highly promising for interaction with other acidic proteins to form heteroprotein complex coacervation (HPCC) with a wide range of applications. This review extensively examines the structure, properties, and preparation methods of these basic proteins and delves into the internal and external factors influencing the formation of HPCC, including pH, ionic strength, mixing ratio, total protein concentration, temperature, and inherent protein properties. The applications of different HPCCs based on these three basic proteins are discussed, including the encapsulation of bioactive molecules, emulsion stabilization, protein separation and extraction, nanogel formation, and the development of formulas for infants. Furthermore, the challenges and issues that are encountered in the formation of heteroprotein complexes are addressed and summarized, shedding light on the complexities and considerations involved in utilizing HPCC technology in practical applications. By harnessing the basic proteins to interact with other proteins and to form complex coacervates, new opportunities arise for the development of functional food products with enhanced nutritional profiles and functional attributes. [ABSTRACT FROM AUTHOR]

Magnetic Co0.5Mn0.5Fe2O4 nanoparticles were successfully prepared via the combustion and calcination process, with an average particle diameter of 31.5 nm and a saturation magnetization of 25.25 emu·g-1, they were employed to adsorbe Congo red (CR) from wastewater, the Pseudo-second-order kinetic and Freundlich isotherm were consistent with the adsorption data, indicating that their adsorption was a multilayer chemisorption process, the thermodynamic investigation showed that the adsorption was a favored exothermic process. The ionic strength of Cl- in CR solution had no obvious effect on the adsorption efficiency of Co0.5Mn0.5Fe2O4 nanoparticles, and the maximum adsorbance was 58.3 mg·g-1 at pH 2, decreasing as the pH of the CR solutions increased from 2 to 12. The ion leaching experiment and XRD demonstrated that Co0.5Mn0.5Fe2O4 nanoparticles had excellent stability, and the relative removal rate was 93.85% of the first time after 7 cycles. Cyclic voltammetry and electrochemical impedance spectroscopy demonstrated that CR was adsorbed onto Co0.5Mn0.5Fe2O4 nanoparticles, and the electrical conductivity of Co0.5Mn0.5Fe2O4 nanoparticles decreased after adsorption of CR. Magnetic Co0.5Mn0.5Fe2O4 nanoparticles displayed a promising application in wastewater treatment. [ABSTRACT FROM AUTHOR]

Eukaryotic translation initiation factor eIF4B is required for efficient cap-dependent translation, it is overexpressed in cancer cells, and may influence stress granule formation. Due to the high degree of intrinsic disorder, eIF4B is rarely observed in cryo-EM structures of translation complexes and only ever by its single structured RNA recognition motif domain, leaving the molecular details of its large intrinsically disordered region (IDR) unknown. By integrating experiments and simulations we demonstrate that eIF4B IDR orchestrates and fine-tunes an intricate transition from monomers to a condensed phase, in which large-size dynamic oligomers form before mesoscopic phase separation. Single-molecule spectroscopy combined with molecular simulations enabled us to characterize the conformational ensembles and underlying intra- and intermolecular dynamics across the oligomerization transition. The observed sensitivity to ionic strength and molecular crowding in the self-association landscape suggests potential regulation of eIF4B nanoscopic and mesoscopic behaviors such as driven by protein modifications, binding partners or changes to the cellular environment. This study reveals how the intrinsically disordered region of eIF4B governs its transition from monomers to oligomers and condensed droplets, providing key insights into how its self-association may be regulated to carry out its cellular functions. [ABSTRACT FROM AUTHOR]

Microplastics, as an emerging pollutant, are widely distributed in freshwater environments such as rivers and lakes, posing immeasurable potential risks to aquatic ecosystems and human health. The migration behaviour of microplastics can exacerbate the degree or scope of risk. A complete understanding of the migration behaviour of microplastics in freshwater environments, such as rivers and lakes, can help assess the state of occurrence and environmental risk of microplastics and provide a theoretical basis for microplastic pollution control. Firstly, this review presents the hazards of microplastics in freshwater environments and the current research focus. Then, this review systematically describes the migration behaviours of microplastics, such as aggregation, horizontal transport, sedimentation, infiltration, stranding, resuspension, bed load, and the affecting factors. These migration behaviours are influenced by the nature of the microplastics themselves (shape, size, density, surface modifications, ageing), environmental conditions (ionic strength, cation type, pH, co-existing pollutants, rainfall, flow regime), biology (vegetation, microbes, fish), etc. They can occur cyclically or can end spontaneously. Finally, an outlook for future research is given. [ABSTRACT FROM AUTHOR]

Background/Objectives: The development of polymer–lipid hybrid nanoparticles (PLNs) is a promising area of research, as it can help increase the stability of cationic lipid carriers. Hybrid PLNs are core–shell nanoparticle structures that combine the advantages of both polymer nanoparticles and liposomes, especially in terms of their physical stability and biocompatibility. Natural polymers such as polyhydroxyalkanoate (PHA) can be used as a matrix for the PLNs' preparation. Methods: In this study, we first obtained stable cationic hybrid PLNs using a cationic liposome (CL) composed of a polycationic lipid 2X3 (1,26-bis(cholest-5-en-3β-yloxycarbonylamino)-7,11,16,20-tetraazahexacosane tetrahydrochloride), helper lipid DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine), and the hydrophobic polymer mcl-PHA, which was produced by the soil bacterium Pseudomonas helmantisensis P1. Results: The new polymer-lipid carriers effectively encapsulated and delivered model mRNA-eGFP (enhanced green fluorescent protein mRNA) to BHK-21 cells. We then evaluated the role of mcl-PHA in increasing the stability of cationic PLNs in ionic solutions using dynamic light scattering data, electrophoretic mobility, and transmission electron microscopy techniques. Conclusions: The results showed that increasing the concentration of PBS (phosphate buffered saline) led to a decrease in the stability of the CLs. At high concentrations of PBS, the CLs aggregate. In contrast, the presence of isotonic PBS did not result in the aggregation of PLNs, and the particles remained stable for 120 h when stored at +4 °C. The obtained results show that PLNs hold promise for further in vivo studies on nucleic acid delivery. [ABSTRACT FROM AUTHOR]

In this work, a micro-solid-phase extraction technique employing polylactic acid (PLA)/ZnO-chitosan bio-nanocomposites was developed to isolate selected triazines from aqueous environments. Subsequently, the isolated analytes were injected into gas chromatography–mass spectrometry instrument following solvent desorption. The PLA bio-nanocomposites, incorporating varying concentrations of synthesized ZnO-chitosan, were fabricated utilizing the solvent casting method. The PLA/ZnO-chitosan bio-nanocomposites and ZnO-chitosan hybrid nanoparticles were analytically characterized by the use of field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, tensile testing, and X-ray diffraction. Tensile tests showed that adding ZnO-chitosan hybrid nanoparticles to PLA increased both its tensile strength and elongation at break. Key parameters of the extraction process involving PLA/ZnO-chitosan bio-nanocomposites such as nanoparticle concentration, ionic strength, sample pH, extraction duration, and solvent choice were meticulously examined and optimized. The refined extraction device exhibited high sensitivity and rapidity, achieving analytical parameters with a detection limit ranging from 0.85 to 2.5 ng L−1 and a quantification limit between 5 and 10 ng L−1. Equilibrium was attained within 20 min. Over a concentration range of 10–1000 ng L–1, the method showed linearity, with a correlation value higher than 0.9997. Having a relative standard deviation between 4 and 8%, repeatability was confirmed at 100 ng L−1. Ultimately, the proposed extraction device's effectiveness was confirmed by successfully recovering specific analytes from natural water samples, with relative recovery percentages ranging from 98 to 102%, indicative of negligible matrix interference. [ABSTRACT FROM AUTHOR]

The use of the consistency index, as determined from fitting rheological data to the Herschel–Bulkley model, is described such that it may yield systematic trends that allow a very convenient description of the dissipative flow properties of linear and branched (bio)polymers in general, both in molecular and weakly associated supramolecular solutions. The effects of charge-mediated interactions by the systematic variation of the ionic strength and hydrogen bonding by a systematic variation in pH, using levels that are frequently encountered in systems used in practice, is investigated. These effects are then captured using the associated changes in the intrinsic viscosity to highlight the above-mentioned trends, while it also acts as an internal standard to describe the data in a concise form. The trends are successfully captured up to 100 times the polymer coil overlap and 100,000 times the solvent viscosity (or consistency index). These results therefore enable the rapid characterization of biopolymer systems of which the morphology remains unknown and may continue to remain unknown due to the wide-ranging monomer diversity and a lack of regularity in the structure, while the macromolecular coil size may be determined readily. [ABSTRACT FROM AUTHOR]

BACKGROUND: β‐Carotene (BC) is difficult to apply effectively in the food industry due to its low solubility and bioavailability. This work aimed to fabricate Moringa oleifera seed protein (MOSP) stabilized emulsions as delivery vehicles for BC and investigate the effect of aqueous phase conditions including pH and ionic strength on this system. RESULTS: All MOSP samples were positively charged and the particle size of MOSP increased with the increase of pH. At pH 5.0 and 0.2 mol L−1 sodium chloride (NaCl), the MOSP emulsion demonstrated the highest stability coefficient and minimal creaming index, while exhibiting a lower release rate in vitro digestion. The rheological behavior of all MOSP emulsions within the frequency range of 0.1–10 Hz was dominated by viscoelasticity, forming an elastic network structure through dispersed droplets. Additionally, the MOSP emulsion loaded with BC prepared at pH 5.0 and 0.2 mol L−1 NaCl displayed enhanced ultraviolet light stability (52.31 ± 0.03% and 51.86 ± 0.05%) as well as thermal stability (72.39 ± 8.67% and 86.78 ± 10.69%). Furthermore, the BC in the emulsion at pH 7.0 exhibited favorable stability (65.14 ± 0.02%) and optimal bioaccessibility (40.30 ± 0.04%) in vitro digestion. CONCLUSION: The results provided reference data for utilizing MOSP as a novel emulsifier and broadening the application of BC in the food industry. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: Epinephrine (EPI) or norepinephrine (NOR) is widely used to treat cardiovascular collapse during lipid emulsion (LE) resuscitation for drug toxicity. However, the effect of LE on the vasoconstriction caused by EPI or NOR remains unknown. The purpose of this study was to examine the effect of an LE (Intralipid) on the vasoconstriction caused by EPI and NOR in isolated rat aorta. Methods: The effect of LE on the vasoconstriction caused by EPI or NOR in isolated rat aorta was examined. Additionally, the effect of LE on the calcium increase caused by EPI or NOR was investigated. The distribution constant (KD: lipid to aqueous phase) of EPI or NOR between a LE (1%) and an aqueous phase was determined. Results: LE (1 and 2%) did not significantly alter vasoconstriction caused by EPI or NOR in isolated endothelium-intact aorta. Moreover, the LE did not significantly alter the increased calcium level caused by EPI or NOR. The log KD of EPI in the LE (1%) was -0.71, -0.99, and -1.00 at 20, 50, and 100 mM ionic strength, respectively. The log KD of NOR in the LE (1%) was -1.22, -1.25, and -0.96 at 20, 50, and 100 mM ionic strength, respectively. Conclusions: Taken together, the Intralipid emulsion did not alter vasoconstriction induced by EPI or NOR that seems to be due to the hydrophilicity of EPI or NOR, leading to sustained hemodynamic support produced by EPI or NOR used during LE resuscitation. [ABSTRACT FROM AUTHOR]

Superabsorbent hydrogels demonstrate positive significance as water-retaining materials in agriculture and gardens. The super water-retaining hydrogel (BASA) based on the bamboo powder with the rich sulfonic acid group and carboxyl group was successfully and efficiently synthesized by ultrasonic wave-assisted and polymerization methods. The preparation process has the advantages of mild conditions and process simplification. The impact of reaction conditions (the ionic strength, pH value, cross-linking agent and initiator content) was systematically studied. Characterization methods such as elemental analysis, FTIR, SEM and TGA indicated that the synthesized super water-retaining agent had excellent water retention properties and good stability. The maximal absorbent capacities in ultrapure water and rainwater reached 1047 g g−1 and 952 g g−1, respectively. The water retention properties of BASA were affected by the water quality and ionic strength of water solution. The swelling process is mainly the hydrogen bonding between the active group and the hydrogen atom of the water molecule and the electrostatic interaction of anionic groups such as sulfonic acid groups, but it also includes the synergistic effect of diffusion process. The outcomes demonstrate that BASA is a powerful water absorption hydrogel for soil water retention agent in the agricultural field. [ABSTRACT FROM AUTHOR]

• S-NZVI/rGO@GG slurry showed excellent stability and mobility performance. • Higher GG concentration, pH, and low ionic strength are beneficial to improve the transportability of S-NZVI/rGO@GG slurry. • Brownian action dominates S-NZVI/rGO@GG slurry deposition in saturated porous media. • CFT, XDLVO, and kinetic fitting were combined to explain attenuated Brownian motion and GG spatial repulsion play a key role in migration. Nanoscale zero-valent iron (NZVI), which has the advantages of small particle size, large specific surface area, and high reactivity, is often injected into contaminated aquifers in the form of slurry. However, the prone to passivation and agglomeration as well as poor stability and mobility of NZVI limit the further application of this technology in fields. Therefore, sulfided NZVI loaded on reduced graphene oxide (S-NZVI/rGO) and guar gum (GG) with shear-thinning properties as stabilizers were used to synthesize S-NZVI/rGO@GG slurries. SEM, TEM, and FT-IR confirmed that the dispersion and anti-passivation of NZVI were optimized in the coupled system. The stability and mobility of the slurry were improved by increasing the GG concentration, enhancing the pH, and decreasing the ionic strength and the presence of Ca2+ ions, respectively. A modified advection-dispersion equation (ADE) was used to simulate the transport experiments considering the strain and physicochemical deposition/release. Meanwhile, colloidal filtration theory (CFT) demonstrated that Brownian motion plays a dominant role in the migration of S-NZVI/rGO@GG slurry, and the maximum migration distance can be increased by appropriately increasing the injection rate. Extended-Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory showed that the excellent stability and migration of S-NZVI/rGO@GG slurry mainly came from the GG spatial forces. This study has important implications for the field injection of S-NZVI/rGO@GG slurry. According to the injection parameters, the injection range of S-NZVI/rGO@GG slurry is effectively controlled, which lays the foundation for the promotion of application in actual fields. [Display omitted] [ABSTRACT FROM AUTHOR]

This study aimed to optimize a liposomal formulation to enhance the stability of a phenolic-rich extract from green walnut husk. Liposomes were prepared using varying concentrations of phosphatidylcholine (0.15–2% w/v), extract (0–1.3% v/v), and sodium laurate (0–0.2% w/v) via ethanol injection and sonication. Characterization included visual appearance, particle size, polydispersity index, surface charge, encapsulation efficiency, and morphology. Stable liposomes were achieved at 0.15% and 0.3% w/v phosphatidylcholine, although with low encapsulation efficiency (<40%). The addition of 0.2% (w/v) sodium laurate improved the stability, especially at higher phosphatidylcholine concentrations, enhancing the electrostatic repulsion. Optimal concentrations of 2% w/v phosphatidylcholine, 0.2% w/v sodium laurate, and 0.6% v/v extract were determined. The liposomes exhibited a spherical unilamellar morphology with a size of 97.5 ± 0.9 nm and a negative surface charge of –39.8 ± 0.9 mV. These nanoliposomes showed 79.7 ± 0.7% encapsulation efficiency and remained stable under pH, temperature, ionic strength, and storage time variations. Overall, the liposomes proved effective in preserving the natural phenolics of walnut husks under challenging environmental conditions. [ABSTRACT FROM AUTHOR]

This work dealt with the extractive performance and behaviors of new three Schiff base amphiphiles ligands derived from 3-mercapto-1,2,4-triazole and different alkyl chains for recovery of nickel(II) from concentrated saline chloride medium (1 M ± 0.01) at 30 ± 1 °C. The chloroform has been used as solvent for research purposes only. The effects of the main experimental parameters such as extraction time, pH, extractant concentration and ionic strength of the aqueous medium on the extraction process of nickel(II) with amphiphilic Schiff bases (ASBn) were studied and compared. The analysis of extraction data revealed that the synthesized Schiff bases exhibit a better and faster extractability than many extractants reported in the literature. The extraction constants, log Kex, of these chelating extractants increased with an increase in the alkyl chain. A good recovery (E = 75–100%± 0.05) of nickel was obtained with amphiphilic Schiff bases. The hydrophobic Schiff base amphiphile (ASB18) was the most effective extractant for nickel ions from chloride solutions in the acidic pH range (2.41 − 2.90 ± 0.02). Ni(II) was readily extracted by ASB18 in 5 min. Extracted complexes NiL2 into chloroform phase were ascertained by slope analysis method for all extractants. The extraction mechanism of nickel(II) have been finally suggested. The results obtained are promising and can find practical applications such as for recovering of Ni(II) from Ni-MH battery wastes and electroplating industries effluents. However, in view of the acute toxicity of the solvent chloroform, implementation of this process in large-scale nickel processing strategies needs to be thoroughly evaluated from an environmental perspective. [ABSTRACT FROM AUTHOR]

Atmospheric aerosol particles can impact the optical depth of mixed-phase clouds through heterogeneous ice nucleation. Ice nucleating particles (INP) are therefore important contributors to global and local climate but remain under-parameterized in climate models, partially due to the complex interaction between composition and processing conditions. In this article, we study the ice nucleation (IN) activity of montmorillonite bentonite clay which is a common model dust INP, utilizing a 150-well microfluidic device. Refreezing tests are carried out for solutions across a range of salinity and pH to determine the impact of composition and processing on droplet freezing behavior, with and without an intermediate relative humidity (RH) cycling step. It is found that freezing order deviation dramatically increases after droplets undergo RH cycling, and the potential influence on IN activity of delamination of clay when subjected to changing RH conditions is discussed. Freezing order deviation decreases with increasing solution ionic strength, a trend linked to the delamination behavior of bentonite clays, and an overall decrease in IN activity at low pH is observed, possibly due in part to pH-dependent changes in clay aggregate size distribution. The authors conclude that pH changes and RH processing, such as those which naturally occur in the atmosphere, have a marked impact on the IN activity of clay-containing aerosol droplets. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

In recent years, the development of various hydrogel types has aimed to address concerns regarding the inefficient utilization of water and nutrients in agricultural settings. However, conflicting outcomes have emerged regarding the effectiveness of hydrogel application in agriculture and its potential negative environmental consequences. Therefore, this comprehensive review seeks to evaluate the functionality of hydrogels as water and nutrient reservoirs, while identifying potential solutions to mitigate their environmental impacts based on previous research. By synthesizing data from prior studies, this review analyzes how the performance of hydrogels may be influenced by soil pH, ionic strength, and other solution chemistry factors in the environment. Notably, this review encompasses a comprehensive assessment of the impact of the environmental matrix on hydrogel performance, which fills an important knowledge gap and provides valuable insights for future research directions and practical applications in agricultural lands. Considering sustainability concerns associated with conventional hydrogel applications, it is recommended to explore biodegradable hydrogels derived from natural materials like cellulose. These biodegradable options offer minimal negative impacts on the environment. Although studies on the economic analysis of hydrogel usage are limited, they play a significant role in identifying current obstacles and promoting the adoption of biodegradable hydrogels. Conventional hydrogels have shown greater commercial benefits, but the increasing focus on environmental concerns has driven the development of nature-based hydrogels (e.g., starch) in recent years. However, the trade-off between the relatively high cost of biodegradable hydrogels and their low environmental impacts necessitates more pilot-scale experiments and political efforts in this field. In summary, this review demonstrates that incorporating sustainable hydrogels into soils can effectively improve water and nutrient retention, ultimately enhancing crop production. These findings suggest a promising and sustainable future for hydrogel applications in agriculture, while emphasizing the need for further research, pilot studies, and concerted efforts to strike a balance between economic viability and environmental considerations. [ABSTRACT FROM AUTHOR]

Sulfonated poly(oxy‐1,4‐phenylene‐oxy‐1,4‐phenylenecarbonyl‐1,4‐phenylene) also known as SPEEK is a chemically robust cation conductor with good solution processability. A thin film (approx. 0.7 μm) coated asymmetrically over a 10 μm diameter microhole in a Teflon substrate film (5 μm thickness) produces ionic diode effects in aqueous electrolyte media even at high ionic strengths up to 2 M NaCl. The enhancement in the ionic diode performance under high salt conditions is tentatively attributed to a (partial) switch from a concentration polarisation effect (dominant for high diode currents) to interfacial polarisation (dominant at low current; proposed for molecularly rigid ionomers). Ionic strength effects on the diode performance seem relatively low further indicative of a mechanism for the diode effect caused by interfacial polarisation without significant concentration polarisation. Preliminary comparison of diode phenomena in aqueous HCl, LiCl, NaCl, and MgCl2 reveals cation specific effects due to interaction with the polymer. [ABSTRACT FROM AUTHOR]

As a leguminous plant, chickpea has been widely concerned by researchers because of its high yield, low production cost, and high protein content. Compared with soy protein, chickpea protein has lower allergenicity, better solubility, and foaming properties. Therefore, chickpea protein is considered a good alternative to animal protein. Currently, chickpea protein is used in products made from flour, such as cookies, breads, and noodles. Chickpea protein emulsion also has many potential applications in food, such as delaying lipid oxidation, transporting nutrients, and serving as a substitute for animal fat. However, the physical, chemical stability and biological activity of chickpea protein emulsion are easily affected by many factors, including salt ionic strength, pH, temperature, and so forth in food processing. In order to better apply chickpea protein emulsions to more real food substrates, it is necessary and meaningful to study the factors that affect the characteristics of the emulsion. The properties of chickpea protein emulsion can be improved by pretreatment of chickpea protein, including pH adjustment, cross‐linking by glutaminase, hydrolysis of by protein hydrolase, formation of complex with glycosides or polysaccharides and acetylation modification. In the future, the optimized and stable chickpea protein emulsion will be more widely used in the food field. [ABSTRACT FROM AUTHOR]

In the environmental field, the advancement of new high-efficiency heavy metal adsorption materials remains a continuous research focus. A novel composite, covalent organic framework-modified biochar (RH-COF), was fabricated via an in-situ polymerization approach in this study. The COF-modified biochar was characterized by elemental analysis, BET analysis, SEM, FT-IR, and XPS. The nitrogen and oxygen content in the modified material increased significantly from 0.96% and 15.50% to 5.40% and 24.08%, respectively, indicating the addition of a substantial number of nitrogen- and oxygen-containing functional groups to the RH-COF surface, thereby enhancing its adsorption capacity for Cd from 4.20 mg g−1 to 58.62 mg g−1, representing an approximately fourteen-fold increase. Both the pseudo-second-order model and the Langmuir model were suitable for describing the kinetics and isotherms of Cd2+ adsorption onto RH-COF. The adsorption performance of Cd2+ by RH-COF showed minimal sensitivity to pH values between 4.0 and 8.0, but could be slightly influenced by ionic strength. Mechanistic analysis showed that the Cd2+ adsorption on RH-COF was dominated by surface complexation and chelation, alongside electrostatic adsorption, surface precipitation, and Cπ–cation interactions. Overall, these findings suggest that the synthesis of COF-biochar composite may serve as a promising remediation strategy while providing scientific support for applying COF in environmental materials. [ABSTRACT FROM AUTHOR]

In order to improve the functionality of cellulosic materials research and development of high performance soluble materials. Therefore, the Fe3O4/CMS composite membrane was prepared by using carboxymethyl salix powder (CMS) and Fe3O4 as raw materials, 1-propenyl-3-methylimidazolium chloride and dimethyl sulfoxide as dissolution system. The effects of swelling time, swelling temperature, pH and ionic strength on the swelling performance of Fe3O4/CMS composite membranes and the swelling kinetics of the composite membranes were studied. The structure of the composite membrane was characterized by SEM, FT-IR, XRD and TG. The results showed that the swelling degree reached 5.54 g·g−1, when the swelling time was 45 min, the swelling temperature was 65°C, the pH was 5 and the ionic strength was 0.08 mol·L−1. The initial phase of dissolution of the composite membrane fits well with the Fickian diffusion model, and the whole dissolution process belongs to the Schott model, indicating that the main role of the dissolution process is the diffusion of water molecules, while the composite membrane can be preserved for a long time at high temperature, which provides sustainability for the composite membrane. The characterization results showed that the surface of Fe3O4/CMS composite film was rough with small grooves. The O-H effect was enhanced and the Fe-O absorption peak appeared at 600 cm−1, indicating that Fe3O4 had been successfully loaded onto the cellulose membrane. The Fe3O4/CMS composite membrane belonged to cellulose type II structure, meanwhile, the composite membrane had good thermal stability. [ABSTRACT FROM AUTHOR]

A novel SiO2/Al2O3/poly(acrylic acid-co-glycidyl methacrylate), SiO2/Al2O3/P(AA-co-GMA), composite was synthesized and evaluated for its effectiveness in adsorbing Co(II) ions from aqueous solutions. The composite was analyzed using various techniques including FTIR, SEM, TGA, DTA, and XRD. The composite displays a high specific surface area of 17.451 m2/g, exceeding that of the corresponding copolymer, which measures 0.236 m2/g. Batch adsorption experiments were conducted to investigate the factors influencing the adsorption capacity of the composite for Co(II) ions. In the pH experiments, it was found that at a solution pH of 3.4, the P(AA-co-GMA) copolymer alone showed limited capability in adsorbing Co(II) ions, achieving only 3.82 mg/g. However, upon integration of SiO2/Al2O3 into the polymer matrix, the composite exhibited a significantly enhanced adsorption capacity of 103.54 mg/g. The adsorption process followed a pseudo-second-order kinetic model and attained equilibrium within 60 min. The Langmuir isotherm model was found to best describe the adsorption behavior, with a maximum adsorption capacity of 217.86 mg/g. The adsorption of Co(II) was significantly affected by the ionic strength, especially with Al3+ displaying a more pronounced impact on the adsorption of Co(II) ions compared to Na+, Ca2+, and Mg2+. Thermodynamic studies indicate that the adsorption process was spontaneous and endothermic. Overall, the SiO2/Al2O3/P(AA-co-GMA) composite material displayed significant adsorption ability for Co(II) ions, making it a suitable option for further development as an effective adsorbent in water treatment applications. [ABSTRACT FROM AUTHOR]

Emulsified meat products are key deep-processing products due to unique flavor and high nutritional value. Myosin dissolves, and protein aggregation and heat-induced gelation occur after myosin unfolds and hydrophobic groups are exposed. Myosin could form interfacial protein membranes and wrap fat globules. Emulsified fat globules may be filled in heat-induced gel networks. Therefore, this review intends to discuss the influences of heat-induced gelation and interfacial adsorption behavior on oil and water retention. Firstly, the mechanism of heat-induced gelation was clarified from the perspective of protein conformation and micro-structure. Secondly, the mechanism of emulsification stability and its factors affecting interfacial adsorption were demonstrated as well as limitations and challenges. Finally, the structure characteristics and application of multi-layer hydrogels in the gelation and emulsification were clarified. It could conclude that the characteristic morphology, spatial conformation and structure adjustment affected heat-induced gelation and interfacial adsorption behavior. Spatial conformation and microstructure were adjusted to improve the oil and water retention by pH, ionic strength, amino acid, oil phase characteristic and protein interaction. Multi-layer hydrogels facilitated oil and water retention. The comprehensive review of gelation and emulsification mechanisms could promote the development of meat products and improvement of meat processing technology. [ABSTRACT FROM AUTHOR]

A microfluidic thread/paper-based analytical device (µTPAD) is of great significance in biomedical analysis and point-of-care diagnostics. Nevertheless, the research has not been done on the ion distribution on the thread and how it affects sensing so far. Inspired by the sweat stains on the clothes, a high-performance µTPAD based on the evaporation-induced ion enrichment is presented for glucose monitoring in salty solutions. In comparison to the multi-ply cotton thread, the single-ply cotton thread exhibits the most significant ion-enrichment capability at the rear segment, which could be attributed to the balance between the water evaporation and the solution replenishment in the thread. The salts accumulated at the rear segment could increase the ionic strength of the solution passed through the thread, promoting the colorimetric reaction on the paper-based sensing unit. The single-ply thread with strong ion-enrichment capability was integrated with a paper-based glucose sensor to prepare a µTPAD for highly sensitive glucose detection in both PBS and artificial sweat (-0.673µM−1 in PBS and − 0.253 µM−1 in artificial sweat). Moreover, the system could detect glucose in human sweat samples with high accuracy and precision. This work may provide a strategy to prepare a highly sensitive µTPAD for precise analysis of substances in bio-fluids, particularly human sweat. [ABSTRACT FROM AUTHOR]

Pharmaceutically active compounds (PACs) are ubiquitous contaminants that can pollute the environment. This study critically analyzes the sorption of PACs to soil materials based on 137 published papers encompassing 106 PACs and 212 soil materials. The batch technique is commonly employed for sorption studies of PACs to soil, but the experimental setups vary in terms of the type and number of PACs, mixing time, solid to liquid (S/L) ratio, solution type, range of initial concentration, and bio-inhibition method. Sorption competition among PACs or between PACs and dissolved organic matter occurs for certain cases. Linear or close to linear behavior was reported for sorption of many PACs to soil, but sorption of some PACs deviates from linearity. The reaction of PACs to soil is fast at the initial stages but slows down as it approaches equilibrium. PACs characteristics, soil properties, and solution attributes intricately influence the sorption process. Zwitterionic PACs exhibit the highest sorption affinity, whereas neutral PACs display increased sensitivity to soil hydrophobicity. The average sorption coefficient (K) ranges from 0.0915 mL/g for anionic sulfonamides to 84725.5 mL/g for zwitterionic norfloxacin. An increase in the molar volume corresponds to heightened sorption for cationic PACs and reduced sorption for anionic PACs. Increasing solubility, soil organic carbon, cation exchange capacity, S/L ratio, and soil surface area while decreasing pH, ionic strength, and temperature result in an increase in K. The values of K determined by the batch technique are higher than their column-determined counterparts, possibly due to variations in the employed residence times between the two systems. Several models have been developed to estimate K of PACs, but they are limited in their applicability to specific PACs and soil types. Future research related to sorption of PACs to soils has been suggested. [ABSTRACT FROM AUTHOR]

In this work, we have studied the stability constants of ternary cobalt(II) complexes with the primary ligands: pyridine-2,3-dicarboxylic acid (H22,3-Dipic, H2L) and pyridine-3,4-dicarboxylic acid (H23,4-Dipic, H2L) and secondary ligands representing low molecular mass components of blood serum: lactic acid (HLac), oxalic acid (H2Ox), citric acid (H3Cit), and phosphoric acid (H3PO4). Potentiometric data were analyzed using the least squares computational program LETAGROP. Ionic strength and temperature were both kept constant using 1.0 mol dm−3 NaNO3 as ionic medium at 25 °C. Species distribution diagrams were generated to determine the speciation variations with respect to pH. [ABSTRACT FROM AUTHOR]

The formation of mononuclear complexes and a heterovalent compound in the FeII—FeIII—l-Ala—H2O system was observed when using the Clark—Nikolsky oxidation potential at a temperature of 298.15 K and an ionic strength of the (Na(H)ClO4) solution equal to 0.75 mol L−1. The method of successive approximations (iteration) of the Yusupov oxidation function was used to calculate the stability and the model parameters of the mononuclear coordination compounds [FeHL(H2O)5]3+, [Fe(HL)2(H2O)4]3+, [Fe2(HL)2(OH)4(H2O)6]2+, [FeIIIFeII(HL)2(OH)4(H2O)6]+, [FeHL(H2O)5]2+, [Fe(HL)(OH)(H2O)4]+, and [Fe(HL)(OH)2(H2O)3]0 (L is an alanine ligand), the formation constants of these complexes, to determine the regions where they are dominant and their maximum degrees of accumulation, as well as to plot the diagrams of their distribution as a function of pH. It was determined that the heterovalent complex is the most stable and dominates up to pH 9.5. [ABSTRACT FROM AUTHOR]

The poor thermal stability of lactoferrin (LF) hinders its bioavailability and use in commercial food products. To preserve LF from thermal denaturation, complexation with other biopolymers has been studied. Here we present the complex formation conditions, structural stability, and functional protection of LF by α‐lactalbumin (α‐LA). The formation of the LF–α‐LA complexes was dependent on pH, mass ratio, and ionic strength. Changing the formation conditions and cross‐linking by transglutaminase impacted the turbidity, particle size, and zeta‐potential of the resulting complexes. Electrophoresis, Fourier‐transform infrared spectroscopy, and circular dichroism measurements suggest that the secondary structure of LF in the LF–α‐LA complex was maintained after complexation and subsequent thermal treatments. At pH 7, the LF–α‐LA complex protected LF from thermal aggregation and denaturation, and the LF retained its functional and structural properties, including antibacterial capacity of LF after thermal treatments. The improved thermal stability and functional properties of LF in the LF–α‐LA complex are of interest to the food industry. [ABSTRACT FROM AUTHOR]

Because of its swelling capacity, compacted bentonite clay is a suitable buffer material in deep geological repositories for high-level nuclear waste. However, this only applies if the swelling capacity is maintained. Accordingly, bentonites have to be stable to changing temperature, humidity, infiltrating fluids or microbial activity. In batch experiments, we investigated combined microbial and thermo-hydro-geochemical effects on the swelling capacity of uncompacted bentonite MX-80. Bentonite was exposed to fluids of different ionic strength and the bacterium Stenotrophomonas bentonitica. Bacterial growth was monitored by counting colony-forming units while the swelling capacity of bentonite was evaluated using in situ XRD at varied temperatures and humidity. The presence of bentonite prolonged the survival of S. bentonitica. However, electron microscopy, XRD and ICP-OES analyses showed neither an interaction of S. bentonitica with bentonite, nor significant changes in the swelling capacity or element composition. The swelling capacity and diffraction peak intensity were, however, strongly reduced by the ionic strength of the fluid and the exposure time. The study highlights that bentonite is affected by thermo-hydro-geochemical and microbial processes to different degrees and that the complexity of different co-occurring factors in potential nuclear waste repositories is important to consider in safety assessments. [ABSTRACT FROM AUTHOR]

The distribution equilibria of Am(III) and Cm(III) between the organic phase of bis(2,4,4-trimethylpentyl)dithiophosphonic acid (purified Cyanex301, HA) in xylene and aqueous solutions containing varying concentrations of formic acid or glycolic acid have been investigated aiming at the separation of the two actinides from each other after the groups separation of Am(III)/Cm(III) from Ln(III) ions. The apparent extraction constants for Am(III) and Cm(III) in the Cyanex301-xylene system are determined to be −8.84 and −9.37, respectively, at 0.01 M ionic strength. The specific ion interaction method (SIT) is used to obtain the stability constants of Am(III) and Cm(III) with nitrate and glycolate for calculating the speciation of the ions in extraction at 25°C and I = 0.01 M. The separation of Cm(III) from Am(III) loaded in 0.5 M HA in xylene can be considerably improved by emplying 0.01 to 0.05 M formic acid or glycolic acid as selective stripping reagents favoring complexation with Cm(III). Specifically, with 0.01 M formic acid or glycolic acid in the aqueous phase, the separation factor (SF) for Am(III) over Cm(III) is improved from 3.61 to 5.87 and 5.26, respectively. Hence, both separations of An(III) from Ln(III) and then Am(III) from Cm(III) are achieved by a selective extraction process at first and then a selective stripping process in one simple efficient system using purified Cyanex301 as extractant in organic phase and carboxylic acids as stripping chelates in aqueous. [ABSTRACT FROM AUTHOR]

This study examines the potential of fungal chitosan derived from Aspergillus niger as a sustainable alternative to traditional petrochemical-based ingredients in cosmetic products. Specifically, the research examines the solubility of fungal chitosan in aqueous solutions of varying ionic strength and its adsorption onto negatively charged surfaces that mimic human hair keratin. The adsorption behavior, water content, and frictional properties of chitosan films were evaluated using a quartz crystal microbalance with dissipation monitoring and a surface force apparatus (SFA). The findings indicated that fungal chitosan exhibits good solubility at a pH of 4.5. Conversely, the adsorption of chitosan is subject to the influence of both polymer concentration and ionic strength. At the lowest ionic strengths, a screening-enhanced adsorption process occurs as a consequence of the reduction in chitosan solubility in the presence of salt. This results in the depletion of polymer chains from the solution and their subsequent deposition. An increase in ionic strength above 15–20 mM results in a worsening of the chitosan–surface interaction, due to the simultaneous screening of both the chitosan and the surface charges. This results in a hindrance to the adsorption process. The deposited films are highly hydrated, and this hydration increases with both polymer concentration and ionic strength. Furthermore, the films exhibit a predominantly elastic behavior, and the response of the films under shear deformations shows a strong dependence on the polymer concentration. These findings contribute to the development of environmentally friendly cosmetic formulations that meet consumer demands for sustainability. [ABSTRACT FROM AUTHOR]

This research identified a marine fungal isolate, Aspergillus sp. strain GAD7, which produces an acidic and sulfated extracellular polysaccharide (EPS) with notable anticoagulant and antioxidant properties. Six fungal strains from the Egyptian Mediterranean Sea were screened for EPS production, with Aspergillus sp. strain GAD7 (EPS-AG7) being the most potent, yielding ~5.19 ± 0.017 g/L. EPS-AG7 was characterized using UV-Vis and FTIR analyses, revealing high carbohydrate (87.5%) and sulfate (24%) contents. HPLC and GC-MS analyses determined that EPS-AG7 is a heterogeneous acidic polysaccharide with an average molecular weight (M w ¯) of ~7.34 × 103 Da, composed of mannose, glucose, arabinose, galacturonic acid, galactose, and lyxose in a molar ratio of 6.6:3.9:1.8:1.3:1.1:1.0, linked through α- and β-glycosidic linkages as confirmed by NMR analysis. EPS-AG7 adopted a triple helix-like conformation, as evidenced by UV-Vis (Congo Red experiment) and circular dichroism (CD) studies. This helical arrangement demonstrated stability under various experimental conditions, including concentration, ionic strength, temperature, and lipid interactions. EPS-AG7 exhibited significant anticoagulant activity, doubling blood coagulation time at a concentration of 3.0 mg/mL, and showed significant antioxidant activity, with scavenging activities reaching up to 85.90% and 58.64% in DPPH and ABTS+ assays at 5.0 mg/mL, and EC50 values of 1.40 mg/mL and 3.80 mg/mL, respectively. These findings highlight the potential of EPS-AG7 for therapeutic applications due to its potent biological activities. [ABSTRACT FROM AUTHOR]

Protein amyloid aggregation is linked with widespread and fatal neurodegenerative disorders as well as several amyloidoses. Insulin, a small polypeptide hormone, is associated with injection-site amyloidosis and is a popular model protein for in vitro studies of amyloid aggregation processes as well as in the search for potential anti-amyloid compounds. Despite hundreds of studies conducted with this specific protein, the procedures used have employed a vast array of different means of achieving fibril formation. These conditions include the use of different solution components, pH values, ionic strengths, and other additives. In turn, this variety of conditions results in the generation of fibrils with different structures, morphologies and stabilities, which severely limits the possibility of cross-study comparisons as well as result interpretations. In this work, we examine the condition–structure relationship of insulin amyloid aggregation under a range of commonly used pH and ionic strength conditions as well as solution components. We demonstrate the correlation between the reaction solution properties and the resulting aggregation kinetic parameters, aggregate secondary structures, morphologies, stabilities and dye-binding modes. [ABSTRACT FROM AUTHOR]

MiR-155 is a multifunctional microRNA involved in many biological processes. Since miR-155 is overexpressed in several pathologies, its detection deserves high interest in clinical diagnostics. Biosensing approaches often exploit the hybridization of miR-155 with its complementary strand. Molecular Dynamics (MD) simulations were applied to investigate the complex formed by miR-155 and its complementary strand in aqueous solution with Na+ and Cl− ions at ionic strengths in the 100–400 mM range, conditions commonly used in biosensing experiments. We found that the main structural properties of the duplex are preserved at all the investigated ionic strengths. The radial distribution functions of both Na+ and Cl− ions around the duplex show deviation from those of bulk with peaks whose relative intensity depends on the ionic strength. The number of ions monitored as a function of the distance from the duplex reveals a behavior reminiscent of the counterion condensation near the duplex surface. The occurrence of such a phenomenon could affect the Debye length with possible effects on the sensitivity in biosensing experiments. [ABSTRACT FROM AUTHOR]

The excessive utilization of antimicrobials in humans and animals has resulted in considerable environmental contamination, necessitating the development of high-performance antibiotic adsorption media. A significant challenge is the development of composite nanofibrous materials that are both beneficial and easy to fabricate, with the aim of improving adsorption capacity. Herein, a new kind of zeolitic imidazolate framework-8 (ZIF-8)-modified regenerated cellulose nanofibrous membrane (ZIF-8@RC NFM) was designed and fabricated by combining electrospinning and in situ surface modification technologies. Benefiting from its favorable surface wettability, enhanced tensile strength, interconnected porous structure, and relatively large specific surface area, the resulting ZIF-8@RC NFMs exhibit a relatively high adsorption capacity for tetracycline hydrochloride (TCH) of 105 mg g−1 within 3 h. Moreover, a Langmuir isotherm model and a pseudo-second-order model have been demonstrated to be more appropriate for the description of the TCH adsorption process of ZIF-8@RC-3 NFMs. Additionally, this composite fibrous material could keep a relatively stable adsorption capability under various ionic strengths. The successful fabrication of the novel ZIF-8@RC NFMs may shed light on the further development of wastewater adsorption treatment materials. [ABSTRACT FROM AUTHOR]