Effect Of Surface Charge Research Articles

Application of community data to surface complexation modeling framework development: Iron oxide protolysis

This study presents a comprehensive community data-driven surface complexation modeling framework for simulating potentiometric titration of mineral surfaces. Compiled community data for ferrihydrite, goethite, hematite, and magnetite are fit to produce representative protolysis constants that can reproduce potentiometric titration data collected from multiple literature sources. Using this framework, the impact of surface complexation model type and surface site density (SSD) on the fit quality and protolysis constants can be readily evaluated. For example, the non-electrostatic model yielded a poor data fit compared to diffuse double layer model and constant capacitance models due to the absence of known surface charge effects. Regardless of the choice of iron oxide mineral, pKa1 decreased with increasing SSD while the opposite tendency was observed for pKa2. This newly developed framework demonstrates a method to reconcile community data-wide potentiometric titration data using Findable, Accessible, Interoperable, Reusable data principles to produce mineral protolysis constants that improve robustness of surface complexation models for applications in metal sorption and reactive transport modeling. The framework is readily expandable (as community data increase) and extensible (as the number of minerals increase). The framework provides a path forward for developing self-consistent, comprehensive, and updateable surface complexation databases for surface complexation and reactive transport modeling.

Time-periodic electromagnetohydrodynamic flow in a circular microtube with surface charge dependent slip

The time-periodic electromagnetohydrodynamic (EMHD) flow in circular microtubes is studied by considering slip boundary conditions. An oscillating electric field and a constant magnetic field orthogonal to each other are applied externally to drive the fluid flow. The slip length considered here depends on the surface charge of the channel, which is generally a more realistic situation as demonstrated by recent experimental work. The velocity is obtained by using the characteristics of the Bessel equation. The influences of surface charge density σs and electrical oscillating Reynolds number Re on velocity and flow rate are discussed in detail. Our results demonstrate the EMHD slip flow rate can be reduced by up to 8.5% at low Reynolds number (Re=1) by considering the surface charge effect on slip, but enhanced by up to 8% at high Reynolds number (Re=50). These theoretical results can provide some theoretical basis for experimental studies.

A Bipolar Separator for Autonomous Suppression of Dendrite Penetration in Zinc Metal Batteries

Zinc metal anodes are attracting much attention to enable more economical and sustainable energy storage devices. However, like other metal anodes, dendritic growths and penetrations of porous separators are still challenging to eliminate. Introducing negative surface charges on the pore walls of separators have been exploited to enforce a uniform incoming Zn-ion flux toward more uniform electrodeposition, but penetrations induced by localized high current densities still remain in available systems. In this work, we report, for the first time, a bipolar separator that exploits the distinct electroosmotic effects of the negative and the positive surface charges. The surface charge effects on Zn dendrite growths were first verified in transparent capillary cells via operando video microscopy. By stacking the positively charged separator over the negatively charged separator as our proof-of-concept, the system offers preemptively a uniform Zn-ion flux through the negative layer yet starve-stops local metal growths that already penetrated the negative layer autonomously. Chronopotentiometry experiments with the symmetric cells reveal extended short-circuit time compared to control cells. Galvanostatic cycle-life experiments of full cells with the bipolar separator showed excellent cycle life of 5,000 cycles at the rate of 10 C, without signs of metal penetration.

Effect of polyplex surface charge on cellular internalization and intracellular trafficking

Effect of polyplex surface charge on cellular internalization and intracellular trafficking

The Potential Impact of Ayurvedic Traditional Bhasma on SARS-CoV- 2- Induced Pathogenesis

Abstract: In India, the presently ongoing infectious COVID-19 wave is caused by the delta variant of SARS-CoV-2 which has also led thousands of causalities across the globe. The government and healthcare agencies are hovering for effective strategies to counter the pandemic. The application of nanotechnology and repurposing of drugs are found an effective approach, not obsolete but partly in managing the COVID-19 disease. It has also immensely boomed the search of productive, reliable, cost-effective, and bio-assimilable alternative solutions. Since ancient times, the traditionally employed Ayurvedic bhasmas opted for diverse infectious diseases, which are now justified as a nanomedicine that could be applied for managing COVID-19 related health anomalies. Like currently existing engineered metal nanoparticles (NPs), the bhasma nanoparticles (BNPs) are also packed with unique physicochemical properties including multi-elemental nanocrystalline composition, size, shape, dissolution, surface charge, hydrophobicity, multi-pathway regulatory, and modulatory effects. Here, it is hypothesized that due to these conformational- and configurational- based physicochemical advantages, bhasma NPs might have promising potential to manage the COVID-19 pandemic and can reduce the incidence of pneumonia-like common lung infections in children as well as old-age-related inflammatory diseases by immunomodulatory, anti-inflammatory, antiviral, and adjuvant-related characteristics.

Synthesis, Characterization and Investigation of Antimicrobial Activity of Orthophtaldehyde Nanoflowers

Objective: Endoscopy procedures are frequently performed in gastroenterology clinics, and disinfection cost, corrosion and toxicity are important problems in this area. For this purpose, hybrid nanoflowers at various pHs were synthesized with orthophtaldehyde (OPA), which has an important in disinfection in these clinics, and the hybrid nanostructures obtained by reducing the amount of orthophtaldehyde use were aimed to also increase the effectiveness of the disinfectant. Methods: OPA nanoflowers (OPA NFs) were synthesized and their effective diameters (hydrodynamic diameters) and surface charges were determined by dynamic light scattering (DLS) and Zeta potential (ZP) measurements, respectively. Antimicrobial activities of orthophtaldehyde and OPA NFs against Staphylococcus aureus (S. aureus) ATCC 25923, Escherichia coli (E. coli) ATCC 35218 and Candida albicans (C. albicans) ATCC 90028 standard strains were evaluated by the liquid microdilution method using percent inhibition method. Results: OPA-based OPA-Cu2+hybridnano flowers (OPANF) were synthesized successfully at different pH values (pH 7.4, 9 and 11). The most effective antimicrobial activity was observed in the nanoflowers synthesized at pH=7.4 for all tested microorganisms. Although the antimicrobial activity decreased as the pH value increased, NFs activity was higher than OPA alone at all pH values (p<0.001). In this study, NFs synthesized with 0.02 mg/ml OPA were found to be 5.2 times more effective for C.albicans, 5.75 times for E.coli and 4.4 times for S.aureus than OPA(0.02 mg/ml). Conclusion: NFs showed very high antimicrobial activity compared to OPA and also promise to be a preferred agent in medical device disinfection providing a high level of disinfection with the use of a few amounts of OPA that use in clinics.

Corundum-structured AlCrNbTi oxide film grown using high-energy early-arriving ion irradiation in high-power impulse magnetron sputtering

Multicomponent or high-entropy oxide films are of interest due to their remarkable structure and properties. Here, energetic ion irradiation is utilized for controlling the phase formation and structure of AlCrNbTi oxide at growth temperature of 500°C. The ion acceleration is achieved by using a high-power impulse magnetron sputtering (HiPIMS) discharge, accompanied by a 10 μs-long synchronized substrate bias (Usync), to minimize the surface charging effect and accelerate early-arriving ions, mainly Al+, O+, Ar2+, and Al2+. By increasing the magnitude of Usync from −100 V to −500 V, the film structure changes from amorphous to single-phase corundum, followed by the formation of high-number-density stacking faults (or nanotwins) at Usync = −500 V. This approach paves the way to tailor the high-temperature-phase and defect formation of oxide films at low growth temperature, with prospects for use in protective-coating and dielectric applications.

Nickel catalyzed chemical vapor deposition grown carbon nanoforest for the efficient removal of potentially toxic chemicals from water

The present study demonstrates Ni-catalyzed growth of carbon nanoforest (CNF)-supported on activated carbon fiber (ACF) via a combination of three steps, viz., calcination, H2-reduction, and catalytic chemical vapour deposition (CCVD) in the presence of acetylene (C2H2) as the carbon source to grow CNF. The physicochemical properties of the material are evaluated by various characterization tools. Transmission electron microscopic (TEM) data confirm that the growth of CNF follows tip-growth mechanism. The material is further tested for its adsorption capacities towards two potentially toxic organic compounds such as 4-nitrophenol (4-NP) and methylene blue (MB) at variable pH values. The material shows excellent adsorption of 4-NP (maximum adsorption capacity of 325.80 mg/g at a pH value of 2) and MB (maximum adsorption capacity of 480.90 mg/g at pH = 12). The high adsorption of 4-NP may be ascribed to the strong π-π interactions between 4-NP and the adsorbent, whereas, excellent adsorption of MB may be attributed to the combined effects of negative surface charge, high surface area, and hydrophilic characteristics of the material. The maximum adsorption capacity data obtained for both 4-NP and MB systems in the present study are superior to most of the literature data. The synthesized material may be useful in the removal of several other potentially toxic organic and inorganic pollutants from water.

High energy electrons induced by nonlinear effect in synchronized dual-level radio frequency pulsing capacitively coupled plasmas

The surface charging effect of positive ions at the trench bottom during the etching of dielectric materials has become a severe problem with the shrinkage of electronic feature dimensions. Pulsed plasmas have been widely used to overcome surface charging issues during plasma etching in industry. In this work, synchronized dual-level radio frequency pulsed modulation on capacitively coupled plasmas is investigated based on 1D3V particle-in-cell/Monte Carlo collision simulations. It is found that the plasma always remains a certain initial density during the dual-level pulse modulation, as the high frequency (HF) source still presents during pulse off time (with a reduced voltage amplitude), which may facilitate high processing efficiency. Meanwhile, many HF sheath oscillations are simulated at the initial stage of a pulse period, which induces vast high energy electrons to strike the electrode. When the HF voltage is maintained at a very low value during the pulse off (i.e. 0.1), more electrons with higher energy bombard the bottom of the trench, effectively alleviating the charging effect. Furthermore, the nonlinear behavior of sheath oscillations is proved to be very sensitive to dual-frequency voltage amplitudes and pulse ramp-up times.

Optimizing Membranes for Osmotic Power Generation

AbstractThe design of ion‐selective membranes is the key towards efficient reverse electrodialysis‐based osmotic power conversion. The tradeoff between ion selectivity (output voltage) and ion permeability (output current) in existing porous membranes, however, limits the upgradation of power generation efficiency for practical applications. Thus, we provide the simple guidelines based on fundamentals of ion transport in nanofluidics for promoting osmotic power conversion. In addition, we discuss strategies for optimizing membrane performance through analysis of various material parameters in membrane design, such as pore size, surface charge, pore density, membrane thickness, ion pathway, pore order, and ionic diode effect. Lastly, a perspective on the future directions of membrane design to further maximize the efficiency of osmotic power conversion is outlined.

Optimizing Membranes for Osmotic Power Generation.

The design of ion-selective membranes is the key towards efficient reverse electrodialysis-based osmotic power conversion. The tradeoff between ion selectivity (output voltage) and ion permeability (output current) in existing porous membranes, however, limits the upgradation of power generation efficiency for practical applications. Thus, we provide the simple guidelines based on fundamentals of ion transport in nanofluidics for promoting osmotic power conversion. In addition, we discuss strategies for optimizing membrane performance through analysis of various material parameters in membrane design, such as pore size, surface charge, pore density, membrane thickness, ion pathway, pore order, and ionic diode effect. Lastly, a perspective on the future directions of membrane design to further maximize the efficiency of osmotic power conversion is outlined.

Nanoparticles in Plants: Uptake, Transport and Physiological Activity in Leaf and Root.

Due to their unique characteristics, nanoparticles are increasingly used in agricultural production through foliage spraying and soil application. The use of nanoparticles can improve the efficiency of agricultural chemicals and reduce the pollution caused by the use of agricultural chemicals. However, introducing nanoparticles into agricultural production may pose risks to the environment, food and even human health. Therefore, it is crucial to pay attention to the absorption migration, and transformation in crops, and to the interaction with higher plants and plant toxicity of nanoparticles in agriculture. Research shows that nanoparticles can be absorbed by plants and have an impact on plant physiological activities, but the absorption and transport mechanism of nanoparticles is still unclear. This paper summarizes the research progress of the absorption and transportation of nanoparticles in plants, especially the effect of size, surface charge and chemical composition of nanoparticle on the absorption and transportation in leaf and root through different ways. This paper also reviews the impact of nanoparticles on plant physiological activity. The content of the paper is helpful to guide the rational application of nanoparticles in agricultural production and ensure the sustainability of nanoparticles in agricultural production.

SF6 Degradation in a γ-Al2O3 Packed DBD System: Effects of Hydration, Reactive Gases and Plasma-Induced Surface Charges

SF6 Degradation in a γ-Al2O3 Packed DBD System: Effects of Hydration, Reactive Gases and Plasma-Induced Surface Charges

Biocathode electrochemical activity and reduction characteristics of Cr(VI) system in microbial fuel cells

AbstractBACKGROUNDThe biocathode of microbial fuel cells (MFCs) offers a simple method for the reductive treatment of Cr(VI), and Cr(VI) is an electron acceptor in cathodes in MFCs. In this study, MFCs with different Cr(VI) contents (7.07–35.35 mg L−1) were considered to evaluate the overall performance of MFCs.RESULTSThe results of electrochemical analysis confirmed that the MFC‐2 biocathode exhibited a higher effective reaction surface, stronger conductivity, and smaller charge transfer resistance (53.63 Ω) than the others. In addition, Cr(VI) had a power output of 75.6 mW m−2 in MFC‐2 and a Cr(VI) cathodic coulombic efficiency of 103.8%. With 14.14 mg L−1 Cr(VI) content, the cathode microbe had the best activity. Cr(VI) reduction followed a pseudo‐first‐order kinetic model, with the rate constant being 0.0139 h−1. Meanwhile, this study analyzed the Cr(VI) reduction in MFCs and the release and acceptance of electrons and protons. Electrically active bacteria such as Proteobacteria were highly enriched on the anode and cathode biofilm, while the Cr(VI)‐reducing bacteria Gammaproteobacteria increased in the biofilm of the cathode.CONCLUSIONThis study helps in the selection of Cr(VI) concentration for the cathode, guaranteeing microbial activity and power generation performance. Microbes have the best electrochemical activity in MFC‐2 (14.14 mg L−1). Meanwhile, the change in anode microbial activity was affected by cathode performance. The microbial community was significantly influenced by Cr(VI). © 2023 Society of Chemical Industry (SCI).

Ion current rectification in asymmetric nanochannels: effects of nanochannel shape and surface charge

Ion current rectification in asymmetric nanochannels: effects of nanochannel shape and surface charge

Biofilm growth monitoring using guided wave ultralong-range Surface Plasmon Resonance: A proof of concept

Unwelcomed biofilms are problematic in food industries, surgical devices, marine applications, and wastewater treatment plants, essentially everywhere where there is moisture. Very recently, label-free advanced sensors such as localized and extended surface plasmon resonance (SPR) have been explored as tools for monitoring biofilm formation. However, conventional noble metal SPR substrates suffer from low penetration depth (100–300 nm) into the dielectric medium above the surface, preventing the reliable detection of large entities of single or multi-layered cell assemblies like biofilms which can grow up to a few micrometers or more. In this study, we propose using a plasmonic insulator-metal-insulator (IMI) structure (SiO2–Ag–SiO2) with a higher penetration depth based on a diverging beam single wavelength format of Kretschmann configuration in a portable SPR device. An SPR line detection algorithm for locating the reflectance minimum of the device helps to view changes in refractive index and accumulation of the biofilm in real-time down to 10−7 RIU precision. The optimized IMI structure exhibits strong penetration dependence on wavelength and incidence angle. Within the plasmonic resonance, different angles penetrate different depths, showing a maximum near the critical angle. At the wavelength of 635 nm, a high penetration depth of more than 4 μm was obtained. Compared to a thin gold film substrate, for which the penetration depth is only ∼200 nm, the IMI substrate provides more reliable results. The average thickness of the biofilm after 24 h of growth was found to be between 6 and 7 μm with ∼63% live cell volume, as estimated from confocal microscopic images using an image processing tool. To explain this saturation thickness, a graded index biofilm structure is proposed in which the refractive index decreases with the distance from the interface. Furthermore, when plasma-assisted degeneration of biofilms was studied in a semi-real-time format, there was almost no effect on the IMI substrate compared to the gold substrate. The growth rate over the SiO2 surface was higher than on gold, possibly due to differences between surface charge effects. On the gold, the excited plasmon generates an oscillating cloud of electrons, while for the SiO2 case, this does not happen. This methodology can be utilized to detect and characterize biofilms with better signal reliability with respect to concentration and size dependence.

Quantifying the Molecular Polarization Response of Liquid Water Interfaces at Heterogeneously Charged Surfaces.

The hydration shells of proteins mediate interactions, such as small molecule binding, that are vital to their biological function or in some cases their dysfunction. However, even when the structure of a protein is known, the properties of its hydration environment cannot be easily predicted due to the complex interplay between protein surface heterogeneity and the collective structure of water's hydrogen bonding network. This manuscript presents a theoretical study of the influence of surface charge heterogeneity on the polarization response of the liquid water interface. We focus our attention on classical point charge models of water, where the polarization response is limited to molecular reorientation. We introduce a new computational method for analyzing simulation data that is capable of quantifying water's collective polarization response and determining the effective surface charge distribution of hydrated surfaces over atomistic length scales. To illustrate the utility of this method, we present the results of molecular dynamics simulations of liquid water in contact with a heterogeneous model surface and the CheY protein.

Modeling plasma-induced surface charge effects on CO2 activation by single atom catalysts supported on reducible and irreducible metal oxides

The accumulation of negative surface charge on catalytic surfaces in the presence of low-temperature plasma (LTP) could influence catalytic performance. However, it is difficult to disentangle the role of surface charging and other LTP catalytic effects in experiment. Herein, we use density functional theory (DFT) modeling to understand the effect of plasma-induced surface charging on CO2 activation by atomically dispersed single atom (SA) catalysts on both reducible and irreducible metal oxide supports. We model CO2 adsorption strength and CO2 dissociation barriers for Co1, Ni1, Cu1, Rh1, Pd1, and Ag1 SAs on both reducible and irreducible supports, namely, CeO2(100), TiO2(101), and γ-Al2O3(110), to elucidate trends. We find that accumulated surface charge on the SA increases the CO2 adsorption strength and decreases the CO2 dissociation barrier for all studied SA/support combinations. For both charged and uncharged (neutral) systems, SAs on the reducible CeO2(100) support generally adsorb CO2 more weakly compared to when on irreducible supports like γ-Al2O3(110). SAs on γ-Al2O3(110) typically have larger barriers for CO2 dissociation for both charged and uncharged systems compared to TiO2(101) and CeO2(100). The magnitude of surface charging effects on CO2 binding energies and dissociation barriers depends sensitively on both the SA and the support. In some cases, the CO2 activation trends qualitatively change between neutral and charged systems for a fixed SA across different supports. This DFT modeling study demonstrates that surface charging should be considered in strong electric fields because it can have a large effect on molecule adsorption and bond-breaking on catalytic surfaces.

More negative charges on roots enhanced manganese(II) uptake in leguminous and non-leguminous poaceae crops.

Manganese (Mn) is an essential micronutrient for plants, whereas excess Mn(II) in soils leads to its toxicity to crops. Mn(II) is adsorbed onto plant roots from soil solution and then absorbed by plants. Root charge characteristics should affect Mn(II) toxicity to crops and Mn(II) uptake by the roots of the crops. However, the differences in the effects of root surface charge on the uptake of Mn(II) among various crop species are not well understood. The roots of nine legumes and six non-legume poaceaewere obtained by hydroponics and the streaming potential method and spectroscopic analysis were used to measure the zeta potentials and functional groups on the roots, respectively. The results indicate that the exchangeable Mn(II) adsorbed by plant roots was significantly positively correlated with the Mn(II) accumulated in plant shoots. Legume roots carried more negative charges and functional groups than non-legume poaceae roots, which was responsible for the larger amounts of exchangeable Mn(II) on legume roots in 2h and the Mn(II) accumulated in their shoots in 48 h. Coexisting cations, such as Ca2+ and Mg2+ , were most effective in decreasing Mn(II) taken up by roots and accumulated in shoots than K+ and Na+ . This was because Ca2+ and Mg2+ could compete with Mn(II) for active sites on plant roots more strongly compared to K+ and Na+ . The root surface charge and functional groups are two important factors influencing Mn(II) uptake by roots and accumulation in plant shoots. © 2023 Society of Chemical Industry.

Study on the plasma characteristics in a needle-plate dielectric barrier discharge with a rotating dielectric plate

The enhancement of plasma generation in atmospheric pressure dielectric barrier discharge (DBD) is gaining increasing interest for various plasma applications. In this paper, the effect of surface charges moving with the rotating dielectric plate on improving the generation of streamer channels is investigated by a statistical analysis of electrical measurements, optical diagnostics, and numerical simulation in a needle-plate DBD device with a rotating dielectric plate. Results suggest that rotating the dielectric plate can improve the spatiotemporal distribution of streamer channels by inducing a bending of the streamer channels and an increase in the number of discharges. Statistical results show that the number of current pulse and discharge energy are increased by 20% and 47%, respectively, at the rotating speed of 160 rps (revolution per second). Based on the interaction between the applied electric field and the electric field induced by surface charges, a formula is proposed to govern the effect of rotating the dielectric plate on the discharge energy and streamer bending. To further understand the mechanism of the influence of rotating the dielectric plate on plasma properties, a 2D fluid model is implemented, and the reduced electric field and streamer propagation are analyzed. Results show that the effective transfer and reuse of surface charges play an important role in the enhancement of plasma generation.