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This study investigates the applicability of six transition metal dichalcogenides to efficient therapeutic drug monitoring of ten antiepileptic drugs using laser desorption/ionization-mass spectrometry. We found that molybdenum ditelluride and tungsten ditelluride are suitable for the sensitive quantification of therapeutic drugs. The contribution of tellurium to the enhanced efficiency of laser desorption ionization was validated through theoretical calculations utilizing an integrated model that incorporates transition-metal dichalcogenides and antiepileptic drugs. The results of our theoretical calculations suggest that the relatively low surface electron density for the tellurium-containing transition metal dichalcogenides induces stronger Coulombic interactions, which results in enhanced laser desorption and ionization efficiency. To demonstrate applicability, up to 120 patient samples were analyzed to determine drug concentrations, and the results were compared with those of immunoassay and liquid chromatography-tandem mass spectrometry. Agreements among these methods were statistically evaluated using the Passing-Bablok regression and Bland-Altman analysis. Furthermore, our method has been shown to be applicable to the simultaneous detection and multiplexed quantification of antiepileptic drugs.

Two-dimensional (2D) transition metal carbides and nitrides (MXenes) are a class of 2D nanomaterials that can offer excellent properties for high-performance supercapacitors. Nevertheless, irreversible restacking of MXene sheets decreases the interlayer spacing, which inhibits the ion intercalation between the MXene nanosheets and finally deteriorates the electrochemical performance of supercapacitors. Herein, aramid nanofibers (ANFs) are mixed with Ti 3 C 2 T x MXene to prepare MXene/ANFs composite films. The restacking of MXene sheets is inhibited by the electrostatic repulsion between ANFs and MXene. The ANFs act as intercalation agents to increase the interlayer spacing of the composite films, which can improve the ion storage ability of supercapacitors. Furthermore, the ANFs enhance the mechanical strength of the composite films due to the strong hydrogen bonding interaction and nanomechanical interlocking between ANFs and MXene, endowing the composite films with self-standing property. The resultant composite films are used as electrodes for flexible solid-state supercapacitors to achieve high specific capacitance (996.5 mF cm -2 at 5 mV s -1 ) and outstanding cycling stability. Thus, this work provides a potential strategy to regulate the properties of 2D nanomaterials, which may expand the application of them in energy storage, ionic separation, osmotic energy conversion and beyond., (© 2024 IOP Publishing Ltd.)

The homing of lymphocytes from blood to gut-associated lymphoid tissue is regulated by interaction between integrin α4β7 with mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) expressed on the endothelium of high endothelial venules (HEVs). However, the molecular basis of mucin-like domain, a specific structure of MAdCAM-1 regulating integrin α4β7-mediated cell adhesion remains obscure. In this study, we used heparan sulfate (HS), which is a highly acidic linear polysaccharide with a highly variable structure, to mimic the negative charges of the extracellular microenvironment and detected the adhesive behaviors of integrin α4β7 expressing 293T cells to immobilized MAdCAM-1 in vitro. The results showed that HS on the surface significantly promoted integrin α4β7-mediated cell adhesion, decreased the percentage of cells firmly bound and increased the rolling velocities at high wall shear stresses, which was dependent on the mucin-like domain of MAdCAM-1. Moreover, breaking the negative charges of the extracellular microenvironment of CHO-K1 cells expressing MAdCAM-1 with sialidase inhibited cell adhesion and rolling velocity of 293T cells. Mechanistically, electrostatic repulsion between mucin-like domain and negative charges of the extracellular microenvironment led to a more upright conformation of MAdCAM-1, which facilitates integrin α4β7-mediated cell adhesion. Our findings elucidated the important role of the mucin-like domain in regulating integrin α4β7-mediated cell adhesion, which could be applied to modulate lymphocyte homing to lymphoid tissues or inflammatory sites.

Sialic acids (SA), negatively charged nine-carbon sugars, have long been implicated in cancer metastasis since 1960's but its detailed functional roles remain elusive. We present a computational analysis of transcriptomic data of cancer vs. control tissues of eight types in TCGA, aiming to elucidate the possible reason for the increased production and utilization of SAs in cancer and their possible driving roles in cancer migration. Our analyses have revealed for all cancer types: (1) the synthesis and deployment enzymes of SAs are persistently up-regulated throughout the progression for all but one cancer type; and (2) gangliosides, of which SAs are part, tend to converge to specific types that allow SAs to pack at high densities on cancer cell surface as a cancer advances. Statistical and modeling analyses suggest that (i) a highly plausible reason for the increased syntheses of SAs is to produce net protons, used for neutralizing the OH− persistently generated by elevated intracellular iron metabolism coupled with chronic inflammation in cancer tissues; (ii) the level of SA accumulation on cancer cell surface strongly correlates with the stage of cancer migration, as well as multiple migration-related characteristics such as altered cell-cell adhesion, mechanical stress, cell protrusion, and contraction; and (iii) the pattern of SA deployment correlates with the 5-year survival rate of a cancer type. Overall, our study provides strong evidence for that the continuous accumulation of SAs on cancer cell surface gives rise to increasingly stronger cell-cell repulsion due to their negative charges, leading to cell deformation by electrostatic force-induced mechanical compression, which is known to be able to drive cancer cell migration established by recent studies.

In this study, a comprehensive force balance model is developed to estimate the equilibrium size of agglomerates formed during the fluidization of nanoparticles with considering the importance of hydrogen bond, van der Waals and gravitational forces. Also, the influence of vapor of different polar materials (including methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and ammonia) on the size of hydrophilic silica nanoagglomerates and consequently their fluidization behavior is studied by experiments in a gas-solid fluidized bed. The results show that using vapor of these polar materials (with hydroxyl groups in their formula) improves the fluidization behavior of hydrophilic silica nanoparticles significantly and results in a higher bed expansion. To justify the improving effect of different vapor of polar materials on fluidization behavior, the electrostatic repulsion force is added to the model and size of agglomerates are calculated in the presence of this force. It is obtained that the results of model are in good agreement with the experimental observations, so that, among all used materials methanol, 2-propanol and ethanol have the most effective impact on fluidization improvement and the smallest size of agglomerates is estimated using physical properties of these three alcohols as well. Finally, the size of agglomerates calculated by the model shows error less than 11% compared with the size of agglomerates measured experimentally by laser. This error is lower than the previous reported ones in the literature.

Poly(vinyl alcohol) (PVA) nanofibrous membranes (NFMs) containing various contents of α-chitin nanowhiskers (CtNWs) or chitosan nanowhiskers (CsNWs) were fabricated via electrospinning. The CtNWs were extracted by acid hydrolysis of chitin obtained from shrimp shells. The CsNWs were prepared by surface deacetylation of CtNWs by alkaline treatment. The CtNWs and CsNWs were characterized using transmission electron microscopy and X-ray diffractometry. The morphological and structural analyses of the PVA NFMs containing CtNWS or CsNWs were conducted by field emission scanning electron microscopy and attenuated total reflectance infrared spectroscopy. Also, the physical properties of the NFMs were investigated using thermogravimetric analysis and texture analyzer. The adsorption capacity toward cationic methylene blue of the PVA NFMs with CtNWs or CsNWs was evaluated using UV–Vis spectrophotometry, and it was found that the electrostatic repulsive force due to the surface positive charges of CtNWs and CsNWs reduced the adsorption performance. [ABSTRACT FROM AUTHOR]

Sialic acids (SA), negatively charged nine-carbon sugars, have long been implicated in cancer metastasis since 1960's but its detailed functional roles remain elusive. We present a computational analysis of transcriptomic data of cancer vs. control tissues of eight types in TCGA, aiming to elucidate the possible reason for the increased production and utilization of SAs in cancer and their possible driving roles in cancer migration. Our analyses have revealed for all cancer types: (1) the synthesis and deployment enzymes of SAs are persistently up-regulated throughout the progression for all but one cancer type; and (2) gangliosides, of which SAs are part, tend to converge to specific types that allow SAs to pack at high densities on cancer cell surface as a cancer advances. Statistical and modeling analyses suggest that (i) a highly plausible reason for the increased syntheses of SAs is to produce net protons, used for neutralizing the OH− persistently generated by elevated intracellular iron metabolism coupled with chronic inflammation in cancer tissues; (ii) the level of SA accumulation on cancer cell surface strongly correlates with the stage of cancer migration, as well as multiple migration-related characteristics such as altered cell-cell adhesion, mechanical stress, cell protrusion, and contraction; and (iii) the pattern of SA deployment correlates with the 5-year survival rate of a cancer type. Overall, our study provides strong evidence for that the continuous accumulation of SAs on cancer cell surface gives rise to increasingly stronger cell-cell repulsion due to their negative charges, leading to cell deformation by electrostatic force-induced mechanical compression, which is known to be able to drive cancer cell migration established by recent studies. [ABSTRACT FROM AUTHOR]

Fish protein hydrolysates have garnered much attention owing to their beneficial properties and potential application. In this study, the effect of different hydrolysis times (4 h, 8 h) of the giant squid hydrolysates (GSHs) on rheological properties and microstructure of konjac glucomannan-κ-carrageenan-locust bean gum gel (P gel) was observed in this study. Rheological measurement showed that GSH-P gels obtained higher viscoelastic modulus and stronger interaction, corresponding to the micro-phase separation of polysaccharides-proteins/peptides and large junction zones, as observed by confocal laser scanning microscopy. The molecular weight distribution and ζ-potential results indicated that the molecular weight and charge density of 4 h-GSH was higher than those of 8 h-GSH, resulting in a greater degree of phase separation from polysaccharides. In conclusion, GSHs can be used as a reinforcing agent for polysaccharide gels to adjust the gel texture, providing a theoretical basis for the development of new gel products. [ABSTRACT FROM AUTHOR]

Electrolysis efficiency is significantly hindered by the bubbles on the electrode surface. Therefore, understanding the bubble evolution process is vital to achieve faster detachment at smaller radii. This study experimentally investigates the impact of surface tension and cathodic potential on hydrogen bubble evolution. The findings indicate that adding a small amount (1 × 10−7 M) of anionic surfactant to the acidic solution (1 M H 2 SO 4) results in a 10% reduction in the bubble detachment radius and a substantial decrease in the bubble growth time by approximately 89%. Additionally, further increasing the surfactant concentration has minimal effect on the growth time but continues to lead to the detachment radius decrease which is assumed to be due to the decreased Marangoni force. This study also identifies three distinct bubble growth modes at different surfactant concentrations, linked to varying levels of surfactant adsorption. Furthermore, a force balance model has been developed to describe the bubble growth process. The study concludes that the solutal Marangoni force decreases while electrostatic repulsion increases with rising surfactant concentration. A reduced solutal Marangoni force and increased electrostatic repulsion – are likely the key factors contributing to the accelerated bubble detachment. • Rapid detachment of H 2 bubbles is found at low surfactant concentrations. • Three hydrogen bubble evolution patterns are observed. • Precisely adjusting the Marangoni force. • A force balance model is established for predicting bubble detachment size. [ABSTRACT FROM AUTHOR]

Ageing is the inevitable fate of carbon nanotubes (CNTs) in natural environments. However, the ageing-induced changes in the mobility of CNTs are still poorly understood. In this study, we investigated the migration of CNTs with different ageing degrees in saturated quartz sand using ultrapure water, fresh water and seawater as background solutions. Ageing could change the physicochemical properties of CNTs, leading to less hydrophobicity, lower hydrodynamic diameter, more negative charge and higher dispersity. As a result, aged CNTs exhibited a higher migration ability than pristine CNTs. Furthermore, DLVO theory and XDLVO theory were applied to explore the interaction between CNTs and between CNTs and quartz sand, respectively. Electrostatic repulsion is the primary force, and the total force is also repulsion and increases with ageing, which is favorable for CNTs to migrate in quartz sand. In fresh water and seawater, high ionic strength reduced the electrostatic repulsion, as well as hydrodynamic diameters and negative charges, and thus ageing exhibited a weaker enhancement on CNTs migration than that in ultrapure water. This work is useful to better understand the migration of aged CNTs and is of great significance to reveal the fate of carbon nanomaterials in nature. [Display omitted] • Ageing enhanced the migration of CNTs in ultrapure water, fresh water and seawater. • Aged CNT exhibited more hydrophilicity with more negative charge. • Electrostatic repulsion is the primary force, which is favorable for the migration of CNTs. • High ionic strength weakened the enhancement of aging on CNTs migration.. [ABSTRACT FROM AUTHOR]

Carboxymethyl starch (CST) was introduced to improve gelatin films and its practical application as edible high-performance films for food packaging and cooking was also investigated. The gelatin films modified by carboxymethyl starch exhibited the transparent appearance, tensile strength, barrier properties (oxygen, water vapor and UV light), and thermal performance (TGA, thermal shrinkage and heat-sealing strength). Resulting from the effect of electrostatic interaction modes on the properties of films, electrostatic repulsion could surpass electrostatic attraction in improving the tensile strength, oxygen barrier property and thermal stability of the films probably due to extensive physical entanglement without aggregation. Analysis of FTIR, zeta potential, interfacial dilatational rheology, shear rheological properties, XRD, Raman, SEM and AFM suggested that hydrogen bonding and electrostatic repulsion contributed to the excellent performance. The packaged food could also be cooked with the prepared film for porridge; and the film slightly influenced the shear rheological properties of porridge and imposed little effect on the odors (Electronic-Nose) of porridge. Hence, the gelatin films modified by carboxymethyl starch could potentially work as the edible inner packaging or the edible quantitative packaging for food, offer convenience for consumers, reduce the packaging waste and avoid an extra burden on environment. • CST improved mechanical and barrier properties (O 2 , moisture and UV light) of films. • CST enhanced the thermal stability, thermal shrinkage and sealing strength of films. • Hydrogen bonds and electrostatic repulsion improved compact matrix and performance. • Excessive CST granules caused the weak interactions and the property deterioration. • The packaged food could cook porridge and slightly affect the rheology and odors. [ABSTRACT FROM AUTHOR]

The purpose of this work was to evaluate the possibility of adding tea saponin (TS) to reduce the synthetic surfactant concentration, and maintain or improve the shelf stability of nanoemulsions. The Zanthoxylum bungeanum essential oil (2.5 wt%) loaded oil-in-water nanoemulsions were co-stabilized by Tween 40 (0.5–2.5 wt%) and TS (0.1–5 wt%). A combination of several analytical techniques, such as dynamic laser scattering, interfacial tension, zeta potential, and transmission electron microscope, were used for the characterization of nanoemulsions. Low levels of TS (0.1–0.5 wt%) with Tween 40 had significant effects on the emulsification, and a nanoemulsion with the smallest droplet diameter of 89.63 ± 0.67 nm was obtained. However, in the presence of high TS concentration (0.5–5 wt%), micelles generated by the non-adsorbed surfactants in the aqueous lead to droplets growth. In addition, the combinations of Tween 40 and TS at the high level (>3.5 wt%) exerted a synergistic effect on stabilizing the nanoemulsions and preventing both Ostwald ripening and coalescence. The negative charged TS endowed the droplets with electrostatic repulsion and steric hinderance appeared to prevent flocculation and coalescence. These results would provide a potential application of natural TS in the preparation and stabilization of nanoemulsions containing essential oil.

A thiol-labeled adenosine triphosphate (ATP) binding aptamer is covalently linked on the surface of gold nanoparticles (AuNPs). This warrants protection of the red AuNPs from aggregation in high salt condition. The dispersed AuNPs can quench the fluorescence of the Tb(III)-MOFs at 547 nm with the excitation wavelength of 290 nm. This is ascribed to the combined action of inner filter effect, dynamic quenching and fluorescence resonance energy transfer. If the aptamer binds ATP to form folded structures, the AuNPs aggregate in high salt medium and the green fluorescence of the Tb(III)-MOFs is recovered. This method shows good sensitivity and selectivity for ATP, and the linear range is from 0.5 to 10 μM of ATP with the detection limitat of 0.32 μM. It was applied to the determination of ATP in (spiked) human plasma with satisfactory recoveries (from 93.2% to 106.3%). Oppositely, when the unlabeled aptamer is used instead of thiol-labeled aptamer in this process, the ATP-aptamer complexes rather than unlabeled aptamer provide greater protection for AuNPs against salt-induced aggregation. It is found that when the aptamer covalently binds to AuNPs, the steric hindrance is dominant for the stabilization of AuNPs; for unlabeled aptamer, the electrostatic repulsion is responsible for their stability, irrespective of whether ATP is present or not. These two different forces lead to the aggregation or dispersion of AuNPs with addition of target in salt solution. [ABSTRACT FROM AUTHOR]

We recently developed a mechanically anisotropic hydrogel with a large internal electrostatic repulsion. The hydrogel is embedded with negatively charged titanate nanosheets that are cofacially oriented by a magnetic field. Because of the anisotropic electrostatic repulsion between the nanosheets, this hydrogel exhibits a large elastic modulus when compressed orthogonal to the nanosheet plane. In this paper, we systematically investigate how the intensity of the electrostatic repulsion affects the internal structure and mechanical property of this anisotropic hydrogel, where the free-ion concentration in the hydrogel medium was the key parameter for moderating the electrostatic repulsion due to its screening effect. With gradually changing the free-ion concentration in the hydrogel, nanoscopic arrangement and mesoscopic domain structure of the nanosheets were characterized by two-dimensional small-angle X-ray scattering (2D SAXS) and confocal laser scanning microscopy (CLSM), respectively. Furthermore, an anisotropic mechanical property of the hydrogel was evaluated by compression test. These results reveal that extensive deionization of the hydrogel medium and the resultant maximization of the electrostatic repulsion induces the nanosheets to adopt a monodomain lamellar structure that occupies the whole space of the hydrogel, thereby enhancing the mechanical anisotropy of the hydrogel. Image 1 • Effects of the electrostatic repulsion on the anisotropic hydrogel were systematically studied. • It was proved that the nanosheets in the hydrogel under the deionized state adopt a monodomain structure. • The enhancement of the electrostatic repulsion largely increased mechanical anisotropy of the hydrogel. [ABSTRACT FROM AUTHOR]

The presence of Cr(VI) in the water/wastewater has serious environmental hazards due to its high toxicity. Ultrafiltration membranes are widely used in water/wastewater treatment due to their low cost and simple operation. However, conventional ultrafiltration membrane has low rejection of ions which limits its application for Cr(VI) removal. In terms of this, the CNT/PVDF/stainless steel mesh conductive ultrafiltration membrane was developed via nonsolvent induced phase separation (NIPS) method in this study. The properties of the membranes were characterized and the mechanism for the removal of Cr(VI) under different operational conditions was investigated. The results showed that the new generate membrane has good electrical conductivity and high mechanical strength. The conductive ultrafiltration membrane can realise the efficient removal of Cr(VI) under the application of voltage. It was found that the electrostatic repulsion between CrO 4 2−/HCrO 4 − and negatively charged membrane plays a main role in Cr(VI) removal in the absence of electrolyte while electrochemical reduction plays an important role in Cr(VI) removal in the presence of electrolyte. Moreover, the removal efficiency of Cr(VI) was positively correlated with the ionic strength and residence time. The acidic condition was favorable for the removal of Cr(VI) when lower cell potentials (1 V, 3 V) were applied to the membrane and the neutral condition was beneficial for the removal of Cr(VI) removal when the applied cell potential increased to 5 V. Increase of the residence time by adjusting membrane operational pressure can further enhance the Cr(VI) removal. The highest removal of Cr(VI) (95.2%) was achieved under the best operation conditions (5 V, pH 7, 100 mM Na 2 SO 4 , 3.4 s residence time). It was demonstrated that the conductive membrane offers a promising way of Cr(VI) removal in the electrochemical filtration system. Image 1 • A novel conductive UF membrane was used to remove Cr (VI). • Electrochemical reduction and electrostatic repulsion resulted in Cr (VI) removal. • High removal rate of Cr (VI) can be achieved by adjusting operational conditions. [ABSTRACT FROM AUTHOR]

The forces of interaction between hydrophilic disperse particles in a humidified dispersion have been analyzed. The minimum volume fraction of water, which is acceptable for the application of DLVO theory formulas in computing the interaction between particles, was determined. It is shown that the formation of thin restricted water layers in gaps between hydrophilic particles gives rise to conditions for the attraction of the latter stipulated by the capillary forces that significantly change the properties of dispersions. [ABSTRACT FROM AUTHOR]

Abstract In this study, we developed a hierarchical thin-film nanofibrous composite (TFNC) membrane with electrospun mat as substrate and hydrophilic nanocellulose as the antifouling barrier layer. We found that, due to the super-hydrophilic nature of the nanocellulose, the contact angle of the barrier layer (20 − 28 °) decreased rapidly with time and reached nearly zero after a few seconds, whereby the membrane flux were remarkably higher (52 L. m − 2. h − 1 ) than conventional polymeric membranes (4 − 14 L. m − 2. h − 1 ) at a very low transmembrane pressure of 0.5 psi. In addition, the membrane surface was considerably more negatively-charged due to the high concentration of carboxylate groups, resulting in higher repulsive electrostatic forces between the barrier layer and the model foulant. As a result, the nanocellulose-based hierarchical membranes exhibited a lower fouling tendency (< 10 %) and a higher degree of protein rejection ratio compared with the conventional membranes (fouling tendency > 30 %). The effect of the nanocellulose layer thickness on the membrane fouling was also examined and it was demonstrated that the nanocellulose barrier layer thickness had a significant effect on the membrane fouling. The higher flux, lower fouling, and good rejection properties of this membrane system suggest nanocellulose is a promising barrier material for filtration membranes for water purification and other separation processes. Graphical abstract Image 1 Highlights • Nanocellulose as antifouling nanolayer was coated on the electrospun membranes. • Effect of nanocellulose layer thickness on membrane fouling and flux was evaluated. • Superhydrophilic nanocellulose-coated membranes outperformed commercial membranes. • Nanocellulose membranes exhibited fouling-resistance and 5 times higher flux values. [ABSTRACT FROM AUTHOR]

Abstract The effects of two different humic acids (HAs), commercial Aldrich HA (AHA) and HA extracted from forest soils (FHA), on the dispersion and stability of three multi-walled carbon nanotubes (MWCNTs) in water were investigated. The amount of MWCNTs suspended in pure water increased with increases in the MWCNT surface oxygen content and solution pH, and the amount decreased as the ionic strength increased. These results indicated that electrostatic repulsion drove the dispersion of MWCNTs. Adsorbed HA greatly enhanced the dispersion and stability of MWCNTs due to the increased steric hindrance and electrostatic repulsion between individual MWCNTs. Suspended MWCNT concentrations and HA adsorption to MWCNTs were positively correlated with low ionic strengths (0–40 mM) and/or pH values between 3 and 7, which were independent of the change in electrostatic repulsion, suggesting that the dispersion of MWCNTs was primarily controlled by steric hindrance. At higher ionic strengths, MWCNTs rapidly precipitated due to the reduction of the electrostatic repulsion between individual MWCNTs. AHA could suspend more MWCNTs than FHA, which was ascribed to the higher molecular weight and aromatic carbon content of AHA that led to greater steric hindrance between individual MWCNTs. This result verified that steric hindrance was the dominant mechanism by which HAs disperse MWCNTs. Graphical abstract Unlabelled Image Highlights • Electrostatic repulsion determined MWCNTs dispersion in pure water. • HA enhanced dispersion of MWCNTs through adsorption and steric hindrance. • AHA suspended more MWCNTs than FHA due to larger size and aromatic carbon. [ABSTRACT FROM AUTHOR]

Abstract We report on a novel DNA affinity biosensor which utilises the capture of a neutral charged single stranded (ss) morpholino DNA on a gold electrode to trigger an electrostatic repulsion of negatively charged silicotungstate anions and, in turn, enabled detection of the hybridisation of complementary base pairs. The repulsion of the anions, as a redox indicator, is reflected by a decrease in its electrochemical response with increasing target ss-DNA concentration. A theoretical framework for DNA detection by the affinity biosensor is proposed and verified by electrochemical measurements in the presence of the target ss-DNA by either dc cyclic voltammetry or Fourier transformed alternating current voltammetry (FTACV). The optimised conditions for the capture of the target ss-DNA and the electrochemical detection include 1 μM thiolated neutral morpholino oligo-nucleotide probe, hybridisation time of 10 min, 0.25 mM [α-SiW 12 O 40 ]4-, and 25 mM phosphate buffer. In addition, the use of the 5th harmonic component of the FTACV gave the most sensitive response for the detection of the target ss-DNA. Under these conditions, the DNA affinity biosensor, based on FTACV detection, achieved a minimum detectable concentration of 0.1 pM ss-DNA and a linear concentration range of 0.1–1000 pM. The biosensor also successfully distinguished between some matched and mismatched base pairs. Graphical abstract fx1 Highlights • Hybridisation of complementary base pairs via the capture of a single stranded morpholino DNA. • Detection of hybridisation by the triggered repulsion of silicotungstate anions from electrode. • Proposal and verification of the theoretical basis for the operation of the DNA affinity biosensor. • Achievement of a minimum detectable concentration of 0.1 pM ss-DNA and a linear range of 0.1–1000 pM. • Selectively distinction between matched and mismatched sequences by the DNA affinity biosensor. [ABSTRACT FROM AUTHOR]

Impacted by the electrostatic repulsion between ultrafiltration (UF) membranes and natural organic matter (NOM), organic fouling precipitates significant operational difficulties in water treatment facilities. This study investigated the applicability of diffusion coefficients as surrogate indicators to evaluate the electrostatic repulsive forces between NOMs and UF membrane surfaces. We utilized three distinct types of NOMs and three different UF membranes, each possessing different charge characteristics. Notably, we found that the reduction in diffusion coefficients was markedly pronounced when membranes rich in ionizable functional groups with strong negative charges were involved, indicating heightened electrostatic repulsion. To confirm the reliability of diffusion coefficient reduction as a surrogate indicator of the electrostatic repulsive force, a comprehensive membrane fouling test was conducted. The results revealed a strong correlation between the two parameters, enhancing our understanding of the intricate dynamics of membrane fouling (R2 = 0.9744–0.9907). Thus, this study proposes the concept of utilizing the reduction in the diffusion coefficient as a surrogate indicator to represent the electrostatic repulsive force between NOMs and the UF membrane surface. This innovative approach contributes to enables proactive and predictive assessments of membrane performance, fostering a shift toward proactive maintenance and enhances the operational efficiency of water treatment facilities. [Display omitted] • Diffusion coefficients of NOMs were evaluated by three different membranes. • GP-NOM showed the lowest diffusivity due to their high molecular weight. • GP-NOM showed less electric double layer compaction by changes in ionic strength. • Diffusivity of SR-FA showed the most substantial reduction by ionic strength changes. • A significant correlation was noted between D PES or PVDF D RC and R PES or PVDF R RC. [ABSTRACT FROM AUTHOR]

Kallistatin, also known as SERPINA4, has been implicated in the regulation of blood pressure and angiogenesis, due to its specific inhibition of tissue kallikrein 1 (KLK1) and/or by its heparin binding ability. The binding of heparin on kallistatin has been shown to block the inhibition of KLK1 by kallistatin but the detailed molecular mechanism underlying this blockade is unclear. Here we solved the crystal structures of human kallistatin and its complex with heparin at 1.9 and 1.8 Å resolution, respectively. The structures show that kallistatin has a conserved serpin fold and undergoes typical stressed-to-relaxed conformational changes upon reactive loop cleavage. Structural analysis and mutagenesis studies show that the heparin binding site of kallistatin is located on a surface with positive electrostatic potential near a unique protruded 310 helix between helix H and strand 2 of β-sheet C. Heparin binding on this site would prevent KLK1 from docking onto kallistatin due to the electrostatic repulsion between heparin and the negatively charged surface of KLK1, thus blocking the inhibition of KLK1 by kallistatin. Replacement of the acidic exosite 1 residues of KLK1 with basic amino acids as in thrombin resulted in accelerated inhibition. Taken together, these data indicate that heparin controls the specificity of kallistatin, such that kinin generation by KLK1 within the microcirculation will be locally protected by the binding of kallistatin to the heparin-like glycosaminoglycans of the endothelium.

Abstract Since the content of alkaloids is usually low in plants and they are easily co-eluted with other constituents, enrichment of alkaloids is essential in the discovery of bioactive lead compounds from natural products. In this paper, an easy SPE enrichment method was developed in a buffer-free solvent system based on electrostatic repulsion mechanism. The feasibility of the new method was verified by successful enrichment of alkaloids from Scopolia tangutica (S. tangutica) with an optimized eluting condition. Then this developed method was applied to other representative plants in different families, including Przewalskia tangutica and Peganum harmala L , Lycoris radiata and Menispermum dauricum DC , which enlarged the scope of applicability. Additionally, the new SPE procedure avoided possible structural change destruction caused by pH change. Simple solvent system, including formic acid (FA) and methanol, would benefit subsequent mass analysis, quantity determination and bioactivity screening, and so on. Highlights • We successfully developed a buffer-free alkaloids enrichment method using AC18 as a RP/SAX material. • AC18 with high charge density could elute alkaloid constituent efficiently and selectively. • This method could enrich alkaloids easily and benefit subsequent procedure such as activity screening and LC–MS analysis. • Mild acidic solvent system helped avoid possible structural damage caused by pH change for pH-sensitive alkaloids. • This method was applied successful in alkaloids enrichment from S. tangutica and four other TCMs. [ABSTRACT FROM AUTHOR]

Highlights • Specific ion effects in soil water infiltration were investigated. • The relationship between water infiltration and particle interactions was quantified. • The internal forces between soil particles determine the soil water infiltration. Abstract Many studies have shown that K+ has more favourable effects on soil water infiltration than Na+, which is a result of specific ion effects or Hofmeister effects. In this study, we employed four alkali metal cation species (Li+, Na+, K+, and Cs+) to determine how the particle interactions influence the water infiltration in a soil with permanent surface charges. Moreover, the defined Hofmeister energy was employed to characterize the specific ion effects. The DLVO force plus the hydration force between two adjacent soil particles mainly determines water infiltration rate through affecting the soil pore-size distribution, which exhibits strong specific ion effects. The hydration force may originate from the surface hydration of soil particles and the hydration of cations in the double layer. The hydration pressure between adjacent soil particles was complexly influenced by electrolyte concentration, Debye length, cationic distribution in the double layer through the Hofmeister energy of cation. [ABSTRACT FROM AUTHOR]

Abstract For the purification of soluble proteins and nucleic acids through ion-exchange, the ampholytic ion-exchange materials (AIEMs) were designed, which possessed both short aliphatic carboxyl and short aliphatic amines/imidazole at optimized ratios on solid supports coated with high density of small zwitterions; under optimized conditions, the soluble ionizable biomacromolecules were adsorbed on those AIEMs via electrostatic attractions and eluted effectively through electrostatic repulsions. As the proof-of-concept, magnetic submicron particles bearing short aliphatic carboxyl and the coats of small zwitterion served as the starting solid supports, which were conjugated with lysine alone, or with lysine plus glycine or N , N ‑dimethylethylenediamine, to yield magnetic AIEMs whose surfaces possessed zero net charges at different pH. Such magnetic AIEMs exhibited ideal efficacy to release acid red 13 as an anion at the elution pH optimized for strong electrostatic repulsions; those magnetic AIEMs were proven absorbing under optimized conditions for the purification of soluble proteins stable at pH close to their isoelectric points and solid-phase extraction of nucleic acids in applicable biological mixtures. Therefore, the designed AIEMs are promising for the high-efficacy purification of ionizable soluble biomacromolecules. [ABSTRACT FROM AUTHOR]

Highlights • Chiral crown-ether bonded phase enabled fast separation of chiral amino acids. • All proteinogenic amino acids except proline were resolved within ten minutes. • Acidic, acetonitrile rich mobile phase reduced hydrophobic interaction. • Electrostatic repulsion reduced the contribution of hydrophilic partition mechanism. • Sample diluent and mobile phase were optimized to avoid peak distortion by water. Abstract The separation mechanism of amino acid enantiomers using a chiral crown ether-bonded stationary phase, CROWNPAK CR-I(+), and acetonitrile (ACN)-rich mobile phases (MPs) was studied. The retention factors of proteinogenic l - amino acids (except proline) formed U-shaped plots against the ACN content in the MP with a sharp increase at a high ACN content, while d - amino acids showed much smaller increases or monotonous decreases in retention within the same range. The use of an acidic, highly organic MP with trifluoroacetic acid (TFA) provided a high enantioselectivity with a short separation time from the contribution of the increased binding of the ammonium group of the analytes to the crown ether functionality of the stationary phase and electrostatic repulsion counteracting the hydrophilic partition mechanism. Optimizing the sample diluent and MP alleviated the peak distortion caused by a moving water band that accompanied the hydrophilic interaction liquid chromatography-like elution conditions. The liquid chromatography/time-of-flight mass spectrometry method with the optimized MP — ACN/ethanol/water/TFA = 80/15/5/0.5 (v/v/v/v) — enabled the determination of eighteen pairs of proteinogenic amino acid enantiomers within 10 min. The conditions also provided the following advantages: (i) fast and highly reproducible separations under isocratic conditions, (ii) high sensitivity and low backpressure using the MP with a high organic content, and (iii) highly reliable peak identification by combining two columns (CR-I(+) and CR-I(-)), reversing the elution orders of the enantiomers. [ABSTRACT FROM AUTHOR]

Peristaltic crawling, which is the moving mechanism of earthworm‐like limbless creatures in narrow spaces, is a challenging target to mimic by using soft materials. Here we report an unprecedented hydrogel actuator that enables not only a peristaltic crawling motion but also reversing its direction. Our cylindrically processed hydrogel contains gold nanoparticles for photothermal conversion, a thermoresponsive polymer network for switching the electrical permittivity of the gel interior, and cofacially oriented 2D electrolytes (titanate nanosheets; TiNSs) to synchronously change their anisotropic electrostatic repulsion. When a hydrogel, which was designed to include cofacially oriented TiNSs along the cylindrical gel axis, is pointwisely photoirradiated with a visible‐light laser, it spatiotemporally expands immediately (<0.5 s) and largely (80 % of its original length) in an isovolumetric manner. When the irradiation spot is moved along the cylindrical gel axis, the hydrogel undergoes peristaltic crawling due to quick and sequential elongation/contraction events and moves oppositely toward the laser scanning direction. Thus, when the scanning direction is switched, the crawling direction is reversed. When gold nanorods are used in place of gold nanoparticles, the hydrogel becomes responsive to a near‐infrared light, which can deeply penetrate into bio tissues. Soft robot: An unprecedented photoresponsive hydrogel actuator enables earthworm‐like peristaltic crawling and reverses its direction by scanning with a laser spotlight. This anomalous optical control was made possible by a rapid, large, repeatable, spatiotemporal, and anisotropic photothermal deformation of a hydrogel that contains gold nanoparticles in titanate nanosheets. [ABSTRACT FROM AUTHOR]

Abstract In this study, the performances of six different types of surfactants, each with a series of concentrations around its critical micelle concentration, were systematically tested as additives of draw solution (DS) to improve the performance of DS in forward osmosis. The influence mechanism of surfactants on DS characteristics, membrane fouling and characteristics of ideal surfactants were discussed comprehensively. The six surfactants showed big differences in considering their effects on the characteristics of DS and their performances, which could be explained by the combined effects of thin dense layer formed by surfactant molecules adsorbed on the surface of supporting layer (SL), blocked pores of SL by micelles aggregation, increased viscosity of DS, improved hydrophilicity of membrane SL and ionization of the hydrophilic groups. The nonionic surfactants could significantly reduce the reverse solute flux, accompanied by sharply decreased water flux and heavy membrane fouling. Compared with nonionic surfactants, the anionic surfactants with their Hydrophile-Lipophilic Balance around 10 could significantly reduce the reverse solute flux while with no or low decrease of water flux and reversible membrane fouling. In our work, Sodium dodecyl benzene sulfonate, at 5 mmol/L concentration, had the best performance on the improvement of DS. Highlights • The changes of water flux, reverse solute flux and Js/Jw responded to a series of surfactants in DS were illustrated. • The anionic surfactants with HLB=10 could sharply reduce the reverse solute flux with no or little decrease of water flux. • The ideal surfactants should be anionic surfactants with balanced hydrophilicity and hydrophobicity. • Sodium dodecyl benzene sulfonate, at 5 mmol/L concentration, had the best performance on the improvement of DS. [ABSTRACT FROM AUTHOR]

Concerns regarding the release of microplastics (MPs) into the environment led us to explore the relationship between the different environmental factors and physicochemical properties of MPs, as well as the change of interaction between MPs and organic pollutants. In this study, the effects of environmental factors (ageing conditions), such as pH, temperature, ionic strength, ageing time, and humic acid (HA) concentration, on the characteristics of MPs and their adsorption toward tetracycline (TC) were systematically investigated. The results showed that ageing factors such as pH, ionic strength, and temperature were found to have little impact on the adsorptive capacity of MPs for TC. However, MPs aged in HA solution exhibited a significant decreased adsorptive capacity for TC. HA, which has numerous functional groups, can cover the surface of MPs and change their hydrophobicity, thereby reducing the adsorption affinity to TC. The electrostatic repulsion between adsorbed HA and TC molecules may also decrease the adsorption of TC. In addition, the competing effect of HA for adsorption sites on the surface of MPs further reduces the adsorption of TC. The data presented in this work provide useful information for understanding the transfer of antibiotics by aged MPs, which is of fundamental importance to assess the environmental impact of MPs. [ABSTRACT FROM AUTHOR]

Abstract: In our previous work, we have shown that “electrostatic forces”, when generated anisotropically in aqueous media by 2D electrolytes upon cofacial orientation, enable the formation of a hydrogel with an anisotropic parameter, as defined by the ratio of elastic moduli E⊥/E∥, of 3.0. Herein, we successfully developed the design strategy for a hydrogel with an anisotropic parameter of no less than 85. This value is not only 28 times greater than that of our previous anisotropic hydrogel but also 6 times larger than the current champion record in synthetic hydrogels (E⊥/E∥∼15). Firstly, we simply lowered ionic contaminants in the hydrogel and were able to enhance the anisotropic parameter from 3.0 to 18. Then, we chose a supporting polymer network allowing the hydrogel to carry a higher interior permittivity. Consequently, the anisotropic parameter was further enhanced from 18 to 85. Owing to the enhanced mechanical anisotropy, our new hydrogel displayed a superb ability of seismic isolation. [ABSTRACT FROM AUTHOR]

Cold denaturation is an intriguing phenomenon that deserves special attention because its rationalization is surely linked to a deeper understanding of the molecular determinants of the marginal stability of small globular proteins dissolved in water and aqueous solutions. It is here reviewed and discussed a theoretical approach that has offered a reliable explanation for the occurrence of both cold and hot denaturations. A cornerstone of the approach is the recognition of the role played by the density of water and its temperature-dependence that are largely determined by the special energetic and geometric features of H-bonds. In fact, the density of water determines the magnitude of the solvent-excluded volume effect, which is a main ingredient of the hydrophobic effect. The relationship between density and solvent-excluded volume effect establishes a strong connection between the physico-chemical properties of water and the conformational stability of small globular proteins. [ABSTRACT FROM AUTHOR]

In this research, the Electrostatic-bag-precipitator (EBP) platform was made of the fully transparent organic glass materials, and the Particle Image Velocimetry (PIV) device was used to carry out the direct test of the charged particles movement in the precipitator. The Electrical Low Pressure Impactor (ELPI+) was applied to test the charge amounts of the outlet of the electrostatic precipitator (ESP) part and the outlet of EBP simultaneously. It was found that the movement of charged particles was both affected by the electrostatic repulsion among the particles and the charged dust layer on the filter cartridges, and the effect was positively correlated with the charge amounts on the particles and the dust layer. The variation law of cumulative charge amounts of the dust layer under different voltages and during different time phases was analyzed indirectly and the corresponding function model was established, hoping to provide reference for the research on the high-efficient trapping technique of fine particles. [ABSTRACT FROM AUTHOR]

In order to alleviate the systemic challenges underlying in Lithium sulfur (Li-S) batteries, the surface of non-polar carbon materials have been widely modified with functional polymeric materials and metal-oxide compounds to chemically interact with polysulfides and thus improve the cycle performance of sulfur cathodes. However, the inherent low conductivity and long-term instability of functional polymers and ceramic materials impede the efficient electrochemical reactions and, in the end, deteriorate the electrochemical performances of Li-S batteries. In this study, we demonstrated a facile and effective approach to customize the surface characteristics of carbon nanotubes (CNTs) via thermal treatments under different atmospheres (oxygen and hydrogen) and exploit these properties for sulfur reservoirs and interlayer barrier in order to enhance the electrochemical performances of Li-S batteries. With the aid of different characteristics of modified CNTs, electrochemical performances of sulfur cathodes were effectively optimized in terms of specific capacity and cycling performance. In addition, when interlayers were coupled with general sulfur cathodes with high sulfur loading mass (2.5 mg cm −1 ), it also showed analogous trends in improving the specific capacity and cycle performance (250 cycles). [ABSTRACT FROM AUTHOR]

Poly(ethylenimine) (PEI)-grafted Sepharose FF with an ionic capacity (IC) of 740 mmol/L (FF-PEI-L740) was modified with succinic anhydride, and six mix-charged resins of different ionic capacities (ICs) were synthesized [denoted as “Am-Cn” according to their anion exchange groups (amino groups) and cation exchange groups (carboxyl groups)]. Protein adsorption behaviors were investigated using bovine serum albumin (BSA) and lysozyme (LZM) as model proteins. The modification led to the net positive charge decrease to approximately zero (A320-C270), and then reversed the net charge to negative till the maximum negatively charge resin A20-C970. Adsorption capacity for BSA decreased from 205 ± 5 mg/mL (FF-PEI-L740) to 65 ± 3 mg/mL (A320-C270), but increased, for LZM, from 31 ± 1 mg/mL (A320-C270) to 281 ± 13 mg/mL (A20-C970) with increasing net negative charge. The uptake rate of BSA or LZM decreased with decreasing net positive charge or increasing net negative charge due to the decreased flexibility of the PEI chains brought from the increased electrostatic attraction or repulsion and/or tight binding due to the high net charge density. Effect of ionic strength (IS) showed that the resins with high net charge densities exhibited high adsorption capacities at high IS. Besides, dynamic binding capacity values achieved as high as 55 mg/mL for BSA and 143 mg/mL for LZM. Chromatographic experiments demonstrated favorable elution of bound proteins at NaCl lower than 370 mmol/L. [ABSTRACT FROM AUTHOR]

The dominant adsorption mechanism of ionizable organic chemicals (IOCs) on carbonaceous materials is still unclear. This study used benzoic acid (BA), o -chlorobenzoic acid (2-CBA) and p -chlorobenzoic acid (4-CBA) as representatives of IOCs to investigate the dominant adsorption mechanism on graphene oxide (GO) and graphite (GP), with a specific emphasis on the impact of pH-dependent K OW . The order of apparent adsorption of the investigated chemicals changed with pH, which could not be explained by their constant K OW . According to our measurement, K OW varied greatly with pH. The pH-dependent adsorption of BA, 2-CBA and 4-CBA were significantly correlated with pH-dependent K OW for both GO and GP. Our observations indicated that the hydrophobic effects may dominate the apparent adsorption of BA, 2-CBA and 4-CBA on GO and GP. Electrostatic repulsion played a minor role in their reduced adsorption at high pH. Negative charge-assisted H-bond and π-π interactions may explain the adsorption of negatively charged BA, 2-CBA and 4-CBA on negatively charged GO. This study implied that pH-dependent K OW rather than constant K OW should be incorporated to understand IOC adsorption as affected by pH. [ABSTRACT FROM AUTHOR]

Poly(sodium 2-acrylamido-2-methylpropanesulfonate) (PAMPSNa) was prepared via reversible addition-fragmentation chain transfer (RAFT) radical polymerization. An ionic liquid polymer (PAMPSP4448) was then prepared by exchanging the pendant counter cation from sodium (Na+) to tributyl-n-octylphosphonium (P4448 +). We studied the ultrasound- and thermo-responsive behaviors of PAMPSP4448 in water. When the aqueous PAMPSP4448 solution was heated from 5 to 50 °C, the solution was always transparent with 100% transmittance. Unimers and interpolymer aggregates coexisted in water in the temperature range 5-50 °C. Generally, hydrogen bonding interactions are broken as the temperature increases due to increased molecular motion. Above 25 °C, the size of the interpolymer aggregates decreased, because hydrophobic interactions inside them were strengthened by dehydration accompanying cleavage of hydrogen bonds between water molecules and the pendant amide or sulfonate groups in PAMPSP4448. Above 25 °C, sonication of the aqueous solution induced an increase in the collision frequency of the aggregates. This promoted hydrophobic interactions between the aggregates to form larger aggregates, and the aqueous solution became turbid. When the temperature was decreased below 8 °C, hydrogen bonds reformed between water molecules and the pendant amide or sulfonate groups, allowing PAMPSP4448 to redissolve in water to form a transparent solution. The solution could be repeatedly controlled between turbidity and transparency by sonication and cooling, respectively. [ABSTRACT FROM AUTHOR]

At high transmembrane electric field, a voltage sensitive ion channel is an insulator; when the field is critically reduced, it becomes a conductor of selected ions. The Channel Activation by Electrostatic Repulsion (CAbER) hypothesis proposes that an ordered polarization field of induced dipoles at the high electric field magnitude of the excitable state is overcome by thermal disorder at a critical depolarization. Increased repulsions between positive charges in the S4 segments cause an allosteric transition in which these segments expand and separate in a chiral proteinquake. The increased space allows the P segments to refold and the ion-semiconducting S5 and S6 segments to relax and expand outward in a breathing mode. Stripped permeant ions enter widened hydrogen bonds in the core helices of these segments. Driven by concentration differences and the electric field, the ions hop along transient pathways across the channel, appearing as fractal, stochastic bursts of single-channel currents. To support order amid thermal fluctuations, an object must be of a minimum size. The critical role of an ion channel's size suggests that the evolution of Metazoa became possible only after its DNA had grown enough to code for proteins larger than the correlation length. [Display omitted] • Branched sidechains are the link between depolarization and S4 movements. • Increased repulsions between positive charges drive the S4 segments apart. • As the pore-forming domain expands, its hydrogen bonds widen to become ion sites. • Permeant ions form fractal, stochastic bursts of current across the membrane. • Evolutionary gene doubling gave rise to large ordered phases of animal ion channels. [ABSTRACT FROM AUTHOR]

Membrane fouling is the bottleneck limiting the wide application of membrane processes. Herein, we adopted an electroactive polyether sulfone (PES) membrane capable of mitigating fouling by various negatively charged foulants. To evaluate anti-fouling performance and the underlying mechanism of this electroactive PES membrane, three types of model foulants were selected rationally (e.g., bovine serum albumin (BSA) and sodium alginate (SA) as non-migratory foulants, yeast as a proliferative foulant and emulsified oil as a spreadable foulant). Water flux and total organic carbon (TOC) removal efficiency in the filtering process of various foulants were tested under an electric field. Results suggest that under electrochemical assistance, the electroactive PES membrane has an enhanced anti-fouling efficacy. Furthermore, a low electrical field was also effective in mitigating the membrane fouling caused by a mixture of various foulants (containing BSA, SA, yeast and emulsified oil). This result can be attributed to the presence of electrostatic repulsion, which keeps foulants away from the membrane surface. Thereby it hinders the formation of a cake layer and mitigates membrane pore blocking. This work implies that an electrochemical control might provide a promising way to mitigate membrane fouling.

Despite the advantages of membrane processes, their high energy requirement remains a major challenge. Fabrication of nanocomposite membranes by incorporating various nanomaterials in the polymer matrix has shown promise for enhancing membrane flux. In this study, we embed functionalized cellulose nanofibers (CNFs) with high aspect ratios in the polymer matrix to create hydrophilic nanochannels that reduce membrane resistance and facilitate the facile transport of water molecules through the membrane. The results showed that the incorporation of 0.1 wt % CNF into the polymer matrix did not change the membrane flux (~15 L · m − 2 · h − 1 ) and Bovine Serum Albumin (BSA) Fraction V rejection, while increasing the CNF content to 0.3 wt % significantly enhanced the flux by seven times to ~100 L · m − 2 · h − 1 , but the rejection was decreased to 60−70%. Such a change in membrane performance was due to the formation of hydrophilic nanochannels by the incorporation of CNF (corroborated by the SEM images), decreasing the membrane resistance, and thus enhancing the flux. When the concentration of the CNF in the membrane matrix was further increased to 0.6 wt %, no further increase in the membrane flux was observed, however, the BSA rejection was found to increase to 85%. Such an increase in the rejection was related to the electrostatic repulsion between the negatively-charged CNF-loaded nanochannels and the BSA, as demonstrated by zeta potential measurements. SEM images showed the bridging effect of the CNF in the nanochannels with high CNF contents.

Experimental evidence was investigated to characterize the behavior of calcium-induced aggregation of wheat germ protein fractions. Added CaCl2 appeared to have more effect on the turbidity of the globulin than the albumin and wheat germ protein isolate. Tire kinetics done with turbidity-time curves suggest that the aggregation occurs via a lag phase (nucleation), growth process and a plateau period. The growth rate of aggregation (the initial slope of turbidity versus time) was increased obviously with an increase in CaCl2 concentration from 50 to 250 mM. If more than 100 mM Ca2+ ions are added, smooth and loose network is fanned by electrostatic repulsion inhibited further aggregation. The degree of globulin aggregation may depend on the stoichiometry ratio of CaCl2/protein and an ion-specific conformational change accompanying the aggregation. The aggregation state of globulins in neutral aqueous solution converting to suspension state can be modulated by calcium addition. Calcium-wheat germ globulin complexes obtained would be a good option for incorporating this mineral into nondairy foods. [ABSTRACT FROM AUTHOR]

We prepared a lenticular microlens array (LMA) using a polyvinyl chloride (PVC) gel and an interdigitated electrode. By applying a DC voltage to the electrode, the surface of the PVC gel can be waved with an LMA character. When the voltage is removed, the wavy PVC gel can recover its flat surface gradually. With the aid of a polarity-inverted voltage, the recovering time can be largely reduced. The LMA can present a stable dynamic response when it is repetitively impacted by a pulse voltage. The experimental results are given, and the mechanism of reducing the dynamic response time is explained. Our LMA with improved response time has potential applications in sensing, beam steering, biometrics, and displays. [ABSTRACT FROM AUTHOR]

Thin-film composite mixed matrix membrane (TFC MMM) with functionalized carbon nanotube (fCNT) blended in polyethersulfone (PES) support layer was synthesized via interfacial polymerization and phase inversion. This membrane was firstly tested in lab-scale integrating seawater desalination and wastewater reclamation forward osmosis (FO) process. Water flux of TFC MMM was increased by 72% compared to that of TFC membrane due to enhanced hydrophilicity. Although TFC MMM showed lower water flux than TFC commercial membrane, enhanced reverse salt flux selectivity (RSFS) of TFC MMM was observed compared to TFC membrane (15% higher) and TFC commercial membrane (4% higher), representing membrane permselectivity. Under effluent organic matter (EfOM) fouling test, 16% less normalized flux decline of TFC MMM was observed compared to TFC membrane. There was 8% less decline of TFC MMM compared to TFC commercial membrane due to fCNT effect on repulsive foulant–membrane interaction enhancement, caused by negatively charged membrane surface. After 10 min physical cleaning, TFC MMM displayed higher recovered normalized flux than TFC membrane (6%) and TFC commercial membrane (4%); this was also supported by visualized characterization of fouling layer. This study presents application of TFC MMM to integrated seawater desalination and wastewater reclamation FO process for the first time. It can be concluded that EfOM fouling of TFC MMM was suppressed due to repulsive foulant–membrane interaction. [ABSTRACT FROM AUTHOR]

Hexavalent chromium (Cr(VI)) contamination in drinking water resources remains a challenge in many parts of the United States, as well as in regions affected by industrial pollution. In this study, we demonstrated how electrically conducting carbon nanotube (CNT) – polyvinyl alcohol (PVA) composite ultrafiltration (UF) membranes can be used to remove Cr(VI) from water through a combined process of electrostatic repulsion, electrochemical reduction, and precipitation. The impact of different operational (flux, contact time, applied electrical potential) and environmental (pH and salinity) conditions on Cr(VI) removal were evaluated. Due to the native electrical potential of the CNT/PVA UF membrane material, approximately 45% removal of 1 ppm Cr(VI) solution was detected under neutral pH conditions in deionized water. Increased Cr(VI) removal was observed with increasing membrane surface charge density, which was accomplished through the application of an external potential (3 V, 5 V and 7 V, membrane as cathode) to the electrically conductive membrane surface. The solution ionic strength showed a significant impact on Cr(VI) removal. By increasing the ionic strength without applying external potential on the membrane, the electrostatic repulsive force between the charged membrane surface and the CrO 4 2- ion was eliminated, and Cr(VI) removal dropped to zero. The highest removal (95%) was achieved when 7 V was applied to the membrane/counter electrode with a 6 µm-thick membrane. Here, Cr(VI) was electrochemically reduced to Cr(III) on the membrane surface, followed by Cr(III) precipitation as chromium hydroxide Cr(OH) 3(s) , which occurred by Cr(III) reacting with hydroxide ions generated via water splitting on the CNT network. Precipitated Cr(OH) 3 was then removed by the UF membrane. In addition, CNT-PVA UF membranes were used to treat tap water spiked with Cr(VI); under these conditions, 99% Cr(VI) removal was observed when 7 V were applied to the membrane/counter electrode. Furthermore, we demonstrate that other trace inorganic contaminants, such as uranium, were effectively removed as well. [ABSTRACT FROM AUTHOR]

Amyloids are polypeptide aggregates involved in many pathologies including Alzheimer's disease. Amyloid assembly is a complex process affected by different interactions including hydrogen bonding, van der Waals forces and electrostatic interactions. The highly regular amyloid structure allows for an arrangement of residues that forces side chains to be closely positioned, giving rise to potentially unfavorable interactions such as electrostatic repulsions. In these cases, amyloid assembly will depend on a balance between stabilizing versus unfavorable interactions. In this study, we rationally designed several amyloid-prone model peptides that had two acidic groups and tested their assembly into amyloids under different conditions. We found that at low pH (pH 4.0), most peptides spontaneously formed amyloids whereas no or little aggregation was observed at higher pHs (pH 8.0). When divalent metals with affinity for carboxylate groups were added at millimolar concentrations, most peptides exhibited a metal-dependent switch to the amyloid state at pH 8.0. Our results show that electrostatic repulsion between amyloid-prone sequences can be overcome in conditions that affect protonation of residue side chains. Moreover, the presence of divalent metals can contribute to electrostatic shielding through specific coordination with acidic groups and thus promote amyloid assembly. [ABSTRACT FROM AUTHOR]

Miniaturization and light weight of aluminum electrolytic capacitor can be achieved via the enhancement in the specific capacitance of anodized aluminum foils resulted from the introduction of compounds with high permittivity into dielectric layer. However, the electrostatic repulsion between the compounds and aluminum substrates hinders this introduction of the compounds, leading to a limited improvement in the specific capacitance. In this work, a novel strategy has been developed to promote the deposition of TiO2 on the surface of aluminum foils by surface modification with polyvinyl alcohol, which sharply decreases the electrostatic repulsion and dramatically increases the mass of deposited TiO2. The evolution of composition and morphology during the process are studied and the capacitor performance of aluminum foils with various treatments is investigated. Interestingly, after surface modification, a specific capacitance of 131.5 µF cm−2 under the withstanding voltage of 21.2 V is obtained, and there is about 60% enhancement in the specific capacitance compared with those without TiO2, and about 30% enhancement compared with those without surface modification, respectively. The specific capacitance obtained is the highest one for aluminum electrolytic capacitor reported to date. These outstanding performances exhibit great potential of this strategy for commercial application on aluminum electrolytic capacitor. [ABSTRACT FROM AUTHOR]

In this short review of hydrophobicity in relation to the caseins and their properties, it is concluded that the scales are weighted heavily in favour of hydrophobic interactions contributing the attractive component in casein self-assembly and casein micelle formation. Multiple clusters of hydrophobic residues are identified as potential reaction sites in the hydrophobic tails and trains of the casein proteins. Multiple examples of the involvement of hydrophobic interactions are listed. The concentration of electrostatic charge in the phosphoserine clusters of the proteins amplifies the range of electrostatic repulsion. The cooperative, concerted nature of the phenomenon takes hydrophobic interaction to a similar operating range to provide the perfect foil to the repulsion. [ABSTRACT FROM AUTHOR]

[Display omitted] • The coexistence of EDTA and phosphate promoted DCF removal by Fe 3 O 4 /Air process. • High electrostatic repulsion of Fe 3 O 4 played a key role in enhanced degradation. • Fe(Ⅱ)-EDTA on Fe 3 O 4 surface served as main sites for H 2 O 2 activation. • Sufficient surface Fe(Ⅱ) on Fe 3 O 4 was maintained during the degradation reaction. • Low-toxicity products were generated after DCF was degraded. Chelating agents are now frequently used to facilitate Fenton and Fenton-like reactions by building complexes with iron. A series of advantages can be exemplified, such as fast circulation of Fe(Ⅲ)/Fe(Ⅱ), enhanced catalytic performance of Fe-ligand, and iron precipitation inhibition, etc. However, few studies explored whether electrostatic repulsion between nanoparticle catalysts had an influence on catalytic performance in ligand-enhanced Fenton-like reactions. In this study, we discovered that the coexistence of 0.1 mM EDTA and 10 mM phosphate dramatically accelerated diclofenac (DCF) degradation by Fe 3 O 4 /Air (∼95% within 20 h). In-depth explorations demonstrated the enhanced electrostatic repulsion between Fe 3 O 4 caused by the addition of EDTA and phosphate played a key role in the promoted DCF degradation. The enhanced electrostatic repulsion between Fe 3 O 4 led to a notable increase in the percentage of Fe-EDTA, which benefited O 2 activation and DCF degradation. Reactive oxygen species (ROS) were mainly generated through one-electron activation mechanism of O 2 and •OH were confirmed to be predominant active species responsible for DCF degradation. Fe(Ⅱ)-EDTA on Fe 3 O 4 surface was evidenced to be served as main sites for O 2 and H 2 O 2 activation. During the degradation reaction, sufficient surface Fe(Ⅱ) on Fe 3 O 4 was maintained with the assistance of EDTA. Toxicity analysis showed that DCF was transformed into less toxic intermediates, demonstrating the feasibility of this technology in practical applications. This work for the first time reveals the importance of electrostatic repulsion between nanoparticle catalysts in ligand-enhanced Fenton-like reactions, providing a low-cost and effective advanced oxidation process for contaminants degradation. [ABSTRACT FROM AUTHOR]

Conventional methods of protecting against airborne pathogens, such as face masks, are typically associated with significant pressure loss and uncomfortable long-term wear. Alternative methods, such as antimicrobial textiles, can utilize nanomaterial-modified functional fabrics for effective microbial prevention, but suffer from limited treatment throughput, high cost, and potential toxicity from nanomaterial release. Herein, we develop a novel microbial-blocking textile using fabrics with opposite triboelectric properties of the outer and inner layers, which induces triboelectric charges by harvesting kinetic energy from human motion. The induced triboelectric negative charges at the outer textile layer achieve efficient airborne pathogen blocking based on electrostatic repulsion between the fabric and microbes. This self-powered, triboelectrification-induced microbial blocking system with optimized material (PTFE and nylon) and structure (rib knitted) achieves highly efficient microbial blocking (>95%) at a very high airflow rate of 2.0 m/s. In addition, the pressure drop for microbial blocking by this novel method is extremely low (<30 Pa). Our results demonstrate a promising method for rapid, self-powered blocking of airborne pathogens by incorporating triboelectric charges from human motion to meet vital public health needs. [Display omitted] ● Human motion-induced triboelectric charges can be harnessed to block pathogens. ● Textiles with negative triboelectric charges block microbes by electrostatic repulsion. ● Triboelectrification-induced textiles enable microbial blocking at high airflow rates. ● Motion-driven antimicrobial textiles are self-powered with low pressure drop. [ABSTRACT FROM AUTHOR]