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Many novel transport phenomena are observed in graphene nanochannels with ultrahigh surface flatness and nano‐ or sub‐nanoscale constraints. Two critical physical parameters, surface slip length, and surface charge, play a vital role in the channel transport process. However, effectively controlling these parameters under such tight constraints remains a significant challenge. Here, it is developed a novel method that combines oxygen ion etching and layer‐by‐layer assembly of 2D material, to prepare graphene nanochannels. During the assembly process, defects are introduced into the graphene surface via oxygen ion etching. A significantly higher conductivity is observed for the pristine graphene channels compared to those with defects on both the upper and lower surfaces. Consistent with this observation, the conductivity of graphene channels with defects on only one surface falls between the two aforementioned values. Combined with theoretical analysis, the conductivity difference is attributed to the surface slip inhibition due to the introduced defects, and the change of surface charge, both caused by oxygen ion etching. By introducing defects, a new method is uncovered for fine‐tuning ion transport in graphene nanochannels. [ABSTRACT FROM AUTHOR]

ABSTRACT Molecular characteristics of emulsifiers such as their molecular weight (MW) and surface charge, not only affect the stability of the emulsion but also can have an impact on its capacity to either inhibit or promote microbial proliferation. These characteristics can affect the behavior of pathogens such as Salmonella Typhimurium in emulsion systems. The growth and thermal resistance of S. Typhimurium were monitored at different oil content levels (20%, 40%, and 60%) in emulsions stabilized by three whey protein‐based emulsifiers: whey protein isolate (WPI), whey protein hydrolysate (WPH), and a modified WPI with an alteration of charge (WPI+). Our study revealed that emulsifier itself with different MW and surface charge had no effect on bacterial growth and inactivation without oil inclusion (p > 0.05). However, it was found that higher bacterial growth rate at 60% oil content emulsion stabilized with WPI+ (0.65 ± 0.03 log CFU/h) than WPI (0.19 ± 0.04 log CFU/h), which showed the charge of emulsifiers has different effects on microbial dynamics in oil‐in‐water emulsion. Interestingly, WPI+ in emulsions also seemed to convey protection against thermal inactivation of bacteria. These data describe a complex interrelationship between the physicochemical characteristics of the emulsifier and its interacting nature with bacterial cells. They throw even more light on the insight about the importance of a strategic approach toward emulsifier selection in food formulations. This is crucial for the food safety and stability of products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two kinds of natural and renewable materials are combined to fabricate novel 2D membranes for osmotic energy conversion. • The heterogeneous membranes help to the balance of the trade-off between ion selectivity and ion flux. • A record power density of ∼16.57 W/m2 is achieved with the synergism of space and surface charge. • The ion transport mechanism is theoretically investigated by numerical simulations based on Poisson and Nernst–Planck models. As promising prospects for renewable power harvesting, two-dimensional (2D) nanochannels for osmotic energy capture in a reverse electrodialysis arrangement have garnered significant attention. However, existing 2D nanochannel membranes have shown limited power generation capabilities due to challenges in balancing ion flux and selectivity. Here, we construct montmorillonite (MMT)/TEMPO-mediated oxidation cellulose nanofibers (TOCNFs) nanocomposite membranes for enhanced ion transmembrane transport. The intercalation of TOCNFs not only enlarges the interlayer distance, but also provides abundant space charge inside the nanochannels. Benefiting from the strong ion selectivity and high ion flux, the composite membrane achieves a remarkable power output of ∼16.57 W/m2 in the gradient of artificial seawater and river water, exceeding that of the state-of-the-art heterogeneous membrane-based osmotic energy conversion systems. Both experimental and theoretical findings confirm that the synergism of space and surface charge plays a crucial role in promoting osmotic energy conversion. This research contributes valuable insights into the optimization of 2D membranes for efficient clean energy harvesting purposes. [ABSTRACT FROM AUTHOR]

Chlorpromazine (CPZ) is a first-generation neuroleptic with well-established antitumor and antiviral properties. Currently, numerous studies are focused on developing new methods for CPZ delivery; however, the knowledge regarding its conjugates with metal nanoparticles remains limited. The aim of this study was to prepare CPZ conjugates with gold nanoparticles (AuNPs) and evaluate their biological activity on human lymphocytes (HUT-78 and COLO 720L), as well as human (COLO 679) and murine (B16-F0) melanoma cells, in comparison to the effects induced by unconjugated CPZ molecules and AuNPs with well-defined properties. During the treatment of cells with CPZ, AuNPs, and CPZ-AuNP conjugates, changes in mitochondrial activity, membrane integrity, and the secretion of lipid peroxidation mediators were studied using standard biological assays such as MTT, LDH, and MDA assays. It was found that positively charged CPZ-AuNP conjugates more effectively reduced cell viability compared to AuNPs alone. The dose-dependent membrane damage was correlated with oxidative stress resulting from exposure to CPZ-AuNP conjugates. The activity of the conjugates depended on their composition and the size of the AuNPs. It was concluded that conjugating CPZ to AuNPs reduced its biological activity, while the cellular response to the treatment varied depending on the specific cell type. [ABSTRACT FROM AUTHOR]

The application of binary gas mixtures consisting of heptafluorobutyronitrile (C4F7N) and carbon dioxide (CO2) in AC GIS is currently attracting much attention. Therefore, the evaluation of the gas–solid interface charge distribution characteristics of epoxy resin is indispensable. Additionally, the phase-dependency of the charging behavior remains not fully understood. We simulated coaxial electrode structure in GIS and investigated the surface charge distribution on a down-scaled epoxy insulator. The influence of the truncated phase angle and duration of AC voltage on charge behavior were analyzed, and the charge transport mechanism under AC voltage was theoretically analyzed. The results showed that there was a noticeable negative charge speckle with the presence of the metal particle and the accumulated negative charge on the insulator surface far exceeded that of the positive charge. The maximum surface charge density and the amount of surface charge accumulated first increased and then decreased over time. It was found that the phase angle has a negligible influence on the surface charge distribution at the cut-off moment. [ABSTRACT FROM AUTHOR]

Lipid nanoparticles (LNPs) are currently the most commonly used non-viral gene delivery system. Their physiochemical attributes, encompassing size, charge and surface modifications, significantly affect their behaviors both in vivo and in vitro. Nevertheless, the effects of these properties on the transfection and distribution of LNPs after intramuscular injection remain elusive. In this study, LNPs with varying sizes, lipid-based charges and PEGylated lipids were formulated to study their transfection and in vivo distribution. Luciferase mRNA (mLuc) was entraped in LNPs as a model nucleic acid molecule. Results indicated that smaller-sized LNPs and those with neutral potential presented superior transfection efficiency after intramuscular injection. Surprisingly, the sizes and charges did not exert a notable influence on the in vivo distribution of the LNPs. Furthermore, PEGylated lipids with shorter acyl chains contributed to enhanced transfection efficiency due to their superior cellular uptake and lysosomal escape capabilities. Notably, the mechanisms underlying cellular uptake differed among LNPs containing various types of PEGylated lipids, which was primarily attributed to the length of their acyl chain. Together, these insights underscore the pivotal role of nanoparticle characteristics and PEGylated lipids in the intramuscular route. This study not only fills crucial knowledge gaps but also provides significant directions for the effective delivery of mRNA via LNPs. [ABSTRACT FROM AUTHOR]

The widespread use of clay minerals and clays in environmental engineering, industry, medicine, and cosmetics largely stems from their adsorption properties and surface charge, as well as their ability to react with water. The dissolution and growth of minerals as a function of pH are closely related to acid–base reactions at their surface sites and their surface charge. The vivid tapestry of different types of surface sites across different types of clay minerals generates difficulties in experimental studies of structure–property relationships. The aim of this paper is to demonstrate how a mesoscale stochastic kinetic Monte Carlo (kMC) approach altogether with atomistic acid-base models and empirical data can be used for understanding the mechanisms of dissolution and surface charge behavior of clay minerals. The surface charge is modeled based on equilibrium equations for de/protonated site populations, which are defined by the pH and site-specific acidity constants (pKas). Lowered activation energy barriers for these sites in de/protonated states introduce pH-dependent effects into the dissolution kinetics. The V-shaped curve observed in laboratory experiments is reproduced with the new kMC model. A generic rate law for clay mineral dissolution as a function of pH is derived from this study. Thus, the kMC approach can be used as a hypothesis-testing tool for the verification of acid–base models for clay and other minerals and their influence on the kinetics of mineral dissolution and growth. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) have been synthesized directly inside liposomes using honey as a reducing agent. The obtained aggregates, named Cassyopea® Gold due to the method used for their preparation, show remarkable properties as reactors and carriers of the investigated AuNPs. A mean size of about 150 nm and negative surface charge of -46 mV were measured for Cassyopea® Gold through dynamic light scattering and zeta potential measurements, respectively. The formation of the investigated gold nanoparticles into Cassyopea® liposomes was spectroscopically confirmed by the presence of their typical absorption band at 516 nm. The catalytic activity of the combined liposome–AuNP nanocomposites was tested via the thermal cis–trans isomerization of resonance-activated 4-methoxyazobenzene (MeO-AB). The kinetic rate constants (kobs) determined at 25 °C in the AuNP aqueous solution and in the Cassyopea® Gold samples were one thousand times higher than the values obtained when performing MeO-AB cis–trans conversion in the presence of pure Cassyopea®. The results reported herein are unprecedented and point to the high versatility of Cassyopea® as a reactor and carrier of metal nanoparticles in chemical, biological, and technological applications. [ABSTRACT FROM AUTHOR]

Precisely co-delivering antigens and immunosuppressants via nano/microcarriers to antigen-presenting cells (APCs) to induce antigen-specific immune tolerance represents a highly promising strategy for treating or preventing autoimmune diseases. The physicochemical properties of nano/microcarriers play a pivotal role in regulating immune function, with particle size and surface charge emerging as crucial parameters. In particular, very few studies have investigated micron-scale carriers of antigens. Herein, various nanoparticles and microparticles (NPs/MPs) with diverse particle sizes (ranging from 200 nm to 5 μm) and surface charges were prepared. Antigen peptides (MOG35–55) and immunosuppressants were encapsulated in these particles to induce antigen-specific immune tolerance. Two emulsifiers, PVA and PEMA, were employed to confer different surface charges to the NPs/MPs. The in vitro and in vivo studies demonstrated that NP/MP-PEMA could induce immune tolerance earlier than NP/MP-PVA and that NP/MP-PVA could induce immune tolerance more slowly and sustainably, indicating that highly negatively charged particles can induce immune tolerance more rapidly. Among the different sizes and charged particles tested, 200-nm-NP-PVA and 3-μm-MP-PEMA induced the greatest immune tolerance. In addition, the combination of NPs with MPs can further improve the induction of immune tolerance. In particular, combining 200 nm-NP-PVA with 3 μm-MP-PEMA or combining 500 nm-NP-PEMA with 3 μm-MP-PVA had optimal therapeutic efficacy. This study offers a new perspective for treating diseases by combining NPs with MPs and applying different emulsifiers to prepare NPs and MPs. [Display omitted] • A systematic comparison of different sized particles was conducted for designing optimal particle-based treatments for autoimmune diseases. • By comparing different sized nanoparticles and microparticles with different negative surface charges, 200-nm-NP-PVA and 3-μm-MP-PEMA were discovered to be optimal in inducing immune tolerance. • A new perspective for inducing antigen-specific immune tolerance by combining NPs together with specific MPs was proposed. [ABSTRACT FROM AUTHOR]

This study investigated the use of cellulose nanocrystals (CNC)/chitosan (Chit) polyelectrolyte complex as a stabilizing agent for Pickering emulsions. We demonstrated that chitosan reduces the surface charge of CNC improving the emulsification process. An optimal stabilizing complex containing 1% chitosan results in emulsions with minimal zeta potential (3.2 ± 0.3 mV), droplet size (2.8 ± 0.8 μm), and creaming index (19.8 ± 1.0%) values, along with high stability during storage, a change in pH, and high centrifugal forces (up to 2000 g). The study also showed that the maximum neutralized surface charge of the CNC in the CNC-Chit complex allows for effective adsorption on the surface of sunflower oil droplets, producing a denser stabilizing layer with a smaller droplet size. Additionally, chitosan addition is linked to improved stability and higher viscosity, with little dependence on ionic strength and temperature. Potentiometric titration revealed that compared with sulfated CNCs, five times less chitosan is needed to neutralize the negative surface charge of acetylated CNC. The wettability of a hydrophilic surface depends on the surface charge of the complex, and the wettability and adhesion performance increase with increasing chitosan content. Additionally, we showed that tuning the stabilizer composition can change the bioaccessibility of lipophilic compounds during oral administration. [ABSTRACT FROM AUTHOR]

Abstract Lipid nanoparticles (LNPs) are currently the most commonly used non-viral gene delivery system. Their physiochemical attributes, encompassing size, charge and surface modifications, significantly affect their behaviors both in vivo and in vitro. Nevertheless, the effects of these properties on the transfection and distribution of LNPs after intramuscular injection remain elusive. In this study, LNPs with varying sizes, lipid-based charges and PEGylated lipids were formulated to study their transfection and in vivo distribution. Luciferase mRNA (mLuc) was entraped in LNPs as a model nucleic acid molecule. Results indicated that smaller-sized LNPs and those with neutral potential presented superior transfection efficiency after intramuscular injection. Surprisingly, the sizes and charges did not exert a notable influence on the in vivo distribution of the LNPs. Furthermore, PEGylated lipids with shorter acyl chains contributed to enhanced transfection efficiency due to their superior cellular uptake and lysosomal escape capabilities. Notably, the mechanisms underlying cellular uptake differed among LNPs containing various types of PEGylated lipids, which was primarily attributed to the length of their acyl chain. Together, these insights underscore the pivotal role of nanoparticle characteristics and PEGylated lipids in the intramuscular route. This study not only fills crucial knowledge gaps but also provides significant directions for the effective delivery of mRNA via LNPs. Graphical Abstract

Abstract Staphylococcus aureus remains a public health threat with the WHO classifying the pathogen as a high priority in the development of new antimicrobial agents. Whole genome sequencing has revealed a number of conserved genes that may be essential for cell viability and infection. Characterising the structure and function of these proteins will inevitably aid development of new antimicrobials. Therefore, this study elucidated the structure of hypothetical protein DUF3055 from S. aureus stain Mu50. The protein possesses an as yet undefined function and a unique fold. The size of DUF3055 made it an ideal candidate for NMR characterisation which in conjunction with circular dichroism revealed the protein to be folded. Crystallisation and structural solution found that the overall dimer fold has a negatively charged surface formed by a β-bulge and tightly crossed α-helices, with a complementary size to a DNA single turn. Our structural observations suggest that hypothetical protein DUF3055 from S. aureus has a role in DNA binding and gene regulation.

A triboelectric nanogenerator (TENG) can effectively convert high entropy mechanical energy from the environment into electrical energy and has broad application potential in self-powered microelectronics and intelligent sensing fields. However, the low output performance of a TENG is one of the bottlenecks that restrict its commercial application. Herein, we design a high-performance and ultrastable wind-driven TENG using a zirconium carbide-zirconia core–shell nanoparticles/polyvinyl chloride (ZrC@ZrO2/PVC) composite membrane and polyamide (PA) membrane as matched triboelectric materials. The investigations indicate that doping 0.9 wt % ZrC@ZrO2 core–shell nanoparticles in the PVC matrix and using 1000-grit sandpaper as a template can effectively boost the surface charge density of the triboelectric layer, so that the output performance of TENG can be improved. The optimized TENG produces a peak output voltage of 367 V, a peak output current of 40 μA, and a maximum output power of 3.2 mW under a wind speed of 17.9 m/s, which can charge a 10,000 uF commercial capacitor from 0 to 3 V within 240 s. The stored energy can supply power for 27 light-emitting diodes (LEDs) connected in parallel. Moreover, the TENG maintains a stable output performance after continuous working for 16 h and a week. This study provides a simple approach to enhance the surface charge density of the friction layer by adding core–shell structured nanoparticles and constructing a rough surface structure. [ABSTRACT FROM AUTHOR]

In this study, we dig to understand the nanoparticle (NP)–cell interaction and the roles of the NP surface charge and the cell membrane potential. While the interaction between negatively charged cadmium selenide/cadmium sulfide (CdSe/CdS) NPs and primary neurons was determined in our previous study, here, by using differentiated mouse neuroblastoma (N2a) cells, nondifferentiated N2a cells, and Chinese hamster ovary (CHO) cells, we are able to understand the relation between electrically excitable cells and non-excitable cells with the same type of NPs in a more systematic way. Indeed, we demonstrate that highly negatively charged CdSe/CdS NPs (−50 mV) interact with the cell membrane of electrically active cells, such as those of primary neurons and differentiated N2a cells, while no interaction occurs with non-electrically active cells, such as CHO cells and nondifferentiated N2a cells. Notably, by ad hoc designed patch-clamp experiments, we confirm that the interaction of the negatively charged NPs with neuronal cells is triggered by the membrane electrical activity. In contrast, no interaction with the cellular membrane is noted in the control unstimulated patch-clamp neuronal cells performed with NPs bearing an almost neutral charge. Furthermore, we show that the interaction between electrically excitable cells occurs with NPs independently of their inorganic nature. Indeed, by replacing the inorganic rod-shaped NPs with negatively charged polymeric micelles made of the same polymer used for the CdSe/CdS NPs surface coating but without the inorganic core (CdSe/CdS NPs), the cell surface interaction still occurs with neuronal excitable cells. These data suggest that, independent of the organic or inorganic nature of the NPs tested here, the specificity of the NP–cell membrane interaction is still affected by the electric activity of the neuronal cells when negatively charged nanoplatforms are used. [ABSTRACT FROM AUTHOR]

Energy transition towards net-zero society calls for utilization of renewable power to drive CO 2 conversion in an efficient electrochemical way. The development of a commercial CO 2 electrolyzer with positive tech-eco effect calls for active and durable electrocatalysts. High-loading gold on carbon (Au/C) with reduced particle size is the prerequisite for the highly-selective and highly energy-efficient CO production in such a CO 2 electrolyzer, but a scalable synthetic method is missing. With combined control of ligand, substrate and pH value, Au/C catalysts with particle size within 5 ​nm and metal loading of 40 ​wt% and 60 ​wt% are synthesized on low and high surface-area carbon, respectively. We also provide a thorough investigation of the effect of the ligand type, surface charge of gold nanoparticles (Au NPs) and surface area of carbon substrate on the loading limit of Au/C. [Display omitted] • High loading Au/C electrocatalyst was synthesized by anchoring small Au nanoparticles onto conductive carbon substrate. • A protocol of tuning the charge between gold nanoparticles and carbon substrate by ligand selection and pH value was developed. • The gold loading on carbon was further enhanced by introducing commercial carbon with large specific surface area. [ABSTRACT FROM AUTHOR]

The precise mechanisms underlying the cellular response to static electric cues remain unclear, limiting the design and development of biomaterials that utilize this parameter to enhance specific biological behaviours. To gather information on this matter we have explored the interaction of collagen type-I, the most abundant mammalian extracellular protein, with poly(vinylidene fluoride) (PVDF), an electroactive polymer with great potential for tissue engineering applications. Our results reveal significant differences in collagen affinity, conformation, and interaction strength depending on the electric charge of the PVDF surface, which subsequently affects the behaviour of mesenchymal stem cells seeded on them. These findings highlight the importance of surface charge in the establishment of the material–protein interface and ultimately in the biological response to the material. The development of new tissue engineering strategies relies heavily on the understanding of how biomaterials interact with biological tissues. Although several factors drive this process and their driving principles have been identified, the relevance and mechanism by which the surface potential influences cell behaviour is still unknown. In our study, we investigate the interaction between collagen, the most abundant component of the extracellular matrix, and poly(vinylidene fluoride) with varying surface charges. Our findings reveal substantial variations in the binding forces, structure and adhesion of collagen on the different surfaces, which collectively explain the differential cellular responses. By exposing these differences, our research fills a critical knowledge gap and paves the way for innovations in material design for advanced tissue regeneration strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) has received significant attention as an energy harvesting technology capable of converting mechanical energy from the environment into electrical power. However, due to its inherent high impedance and low charge transfer output characteristics, the output of TENG is often relatively small. Current research typically focuses on switching on and off under intrinsic voltage for performance management. To further improve output performance, an energy management strategy is proposed that aimed at voltage boosting in this study. This strategy ingeniously designs the discharge sequence of two discharge switches to adjust the connection between the intrinsic capacitor and the matched capacitor, thereby facilitating instantaneous charge transfer under voltages surpassing the intrinsic voltage and significantly enhancing the power density. Combining this strategy with a power converter has significantly enhanced the energy storage efficiency of capacitors, thereby enabling improved power supply for sensor devices. Moreover, experimental results show a power density of 324.8 kW m−2, indicating a 100% increase compared to the direct discharge strategy. With such high output power, five parallel 10‐watt commercial lamps can be illuminated. This strategy introduces a novel idea for achieving high performance output from TENG. [ABSTRACT FROM AUTHOR]

Ionic FETs have enormous potential for energy conversion, sensing, and ionic circuits due to their efficient regulation of the nanochannel. Here ionic FETs based on single‐crystal silicon nanopores and the rectification of the fabricated devices are studied. The electrical characterization results demonstrated that since the silicon‐based nanopores have the advantage of modulating the surface charge due to their semiconductor nature and benefitting from the effective 3D gating effect on the nanochannel, the magnitude and polarity of surface charge can be modulated by the gate voltage. The rectification effect can be adjusted by applying a certain voltage and fulfilling a transition between anion selectivity and cation selectivity when the surface charge polarity is reversed. Moreover, current–voltage characteristics of the reported ionic FET can be switched between ohmic and diode‐like regimes. The proposed ionic FETs supply a novel platform to study the ionic properties and have great potential to be applied in large‐scale ionic circuits due to their excellent performance. Finally, simulation results prove the surface charge modulated by the gate voltage determines the magnitude and direction of rectification, which is consistent with the reported experiment result. [ABSTRACT FROM AUTHOR]

Osseointegration commences with foreign body inflammation upon implant placement, where macrophages play a crucial role in the immune response. Subsequently, during the intermediate and late stages of osseointegration, mesenchymal stem cells (MSCs) migrate and initiate their osteogenic functions, while macrophages support MSCs in osteogenesis. The utilization of ferroelectric P(VDF-TrFE) covered ITO planar microelectrodes facilitated the simulation of various surface charge to investigate their effects on MSCs' osteogenic differentiation and macrophage polarization and the results indicated a parabolic increase in the promotional effect of both with the rise in piezoelectric coefficient. Furthermore, the surface charge with a piezoelectric coefficient of -18 exhibited the strongest influence on the promotion of M1 polarization of macrophages and the promotion of MSCs' osteogenic differentiation. The impact of macrophage polarization and MSC osteogenesis following the interaction of macrophages affected by surface charge and MSC was ultimately investigated. It was observed that macrophages affected by the surface charge of -18 piezoelectric coefficient still exerted the most profound induced osteogenic effect, validating the essential role of M1-type macrophages in the osteogenic differentiation of MSCs. [ABSTRACT FROM AUTHOR]

This study investigated the potential application of geopolymeric material for the separation of oil-in-water emulsions in wastewater treatment. For the first time, an asymmetric membrane made of geopolymers was developed for this specific separation process. The performances of the geopolymeric membrane in oil separation were compared with those obtained by a commercial ceramic membrane. The study also aimed at exploring the effects of emulsion formulation and emulsion properties (surfactant type and concentration, pH, and zeta potential) and membrane parameters (surface charge and material) on permeate volumetric flux and chemical oxygen demand (COD) rejection. Emulsions were prepared using 3% (w/v) dodecane oil in distilled water, with surfactant concentrations of 1x and 10x critical micelle concentration (CMC) and three surfactants of different nature (Oleth-10, Brij 76, and CTAB) at pH values of 2, 5, and 8. Results showed that for the best operating conditions of the geopolymeric membrane, initial and final permeate flux values of 42 and 26 L h−1 m−2, respectively, were achieved. COD rejection values ranged from 95.0 to 99.4% using the geopolymeric membrane thus indicating a very similar behavior between geopolymeric and ceramic membranes. These findings suggest that geopolymers are promising to produce membranes for oil-in-water emulsion microfiltration, promoting an interesting alternative for the treatment of industrial wastewater more sustainable in terms of environmental effects and costs compared to ceramic membranes. • Novel geopolymeric asymmetric membrane was synthetized. • Geopolymer selective layer was successfully deposited on pressed geopolymer support. • The geopolymeric membrane showed excellent fluxes and removal efficiencies. • Flux and rejection properties vary with surfactant concentration and emulsion pH. • Geopolymer membrane performs similarly to a commercial microfiltration ceramic one. [ABSTRACT FROM AUTHOR]

The transition zone (TZ) of hydrocarbon reservoirs is an integral part of the hydrocarbon pool which contains a substantial fraction of the deposit, particularly in carbonate petroleum systems. Consequently, knowledge of its thickness and petrophysical properties, viz. its pore size distribution and wettability characteristic, is critical to optimizing hydrocarbon production in this zone. Using classical formation evaluation techniques, the thickness of the transition zone has been estimated, using well logging methods including resistivity and Nuclear Magnetic Resonance, among others. While hydrocarbon fluids' accumulation in petroleum reservoirs occurs due to the migration and displacement of originally water-filled potential structural and stratigraphic traps, the development of their TZ integrates petrophysical processes that combine spontaneous capillary imbibition and wettability phenomena. In the literature, wettability phenomena have been shown to also be governed by electrostatic phenomena. Therefore, given that reservoir rocks are aggregates of minerals with ionizable surface groups that facilitate the development of an electric double layer, a definite theoretical relationship between the TZ and electrostatic theory must be feasible. Accordingly, a theoretical approach to estimating the TZ thickness, using the electrostatic theory and based on the electric double layer theory, is attractive, but this is lacking in the literature. Herein, we fill the knowledge gap by using the interfacial electrostatic theory based on the fundamental tenets of the solution to the Poisson–Boltzmann mean field theory. Accordingly, we have used an existing model of capillary rise based on free energy concepts to derive a capillary rise equation that can be used to theoretically predict observations based on the TZ thickness of different reservoir rocks, using well-established formation evaluation methods. The novelty of our work stems from the ability of the model to theoretically and accurately predict the TZ thickness of the different lithostratigraphic units of hydrocarbon reservoirs, because of the experimental accessibility of its model parameters. [ABSTRACT FROM AUTHOR]

The transition zone (TZ) of hydrocarbon reservoirs is an integral part of the hydrocarbon pool which contains a substantial fraction of the deposit, particularly in carbonate petroleum systems. Consequently, knowledge of its thickness and petrophysical properties, viz. its pore size distribution and wettability characteristic, is critical to optimizing hydrocarbon production in this zone. Using classical formation evaluation techniques, the thickness of the transition zone has been estimated, using well logging methods including resistivity and Nuclear Magnetic Resonance, among others. While hydrocarbon fluids’ accumulation in petroleum reservoirs occurs due to the migration and displacement of originally water-filled potential structural and stratigraphic traps, the development of their TZ integrates petrophysical processes that combine spontaneous capillary imbibition and wettability phenomena. In the literature, wettability phenomena have been shown to also be governed by electrostatic phenomena. Therefore, given that reservoir rocks are aggregates of minerals with ionizable surface groups that facilitate the development of an electric double layer, a definite theoretical relationship between the TZ and electrostatic theory must be feasible. Accordingly, a theoretical approach to estimating the TZ thickness, using the electrostatic theory and based on the electric double layer theory, is attractive, but this is lacking in the literature. Herein, we fill the knowledge gap by using the interfacial electrostatic theory based on the fundamental tenets of the solution to the Poisson–Boltzmann mean field theory. Accordingly, we have used an existing model of capillary rise based on free energy concepts to derive a capillary rise equation that can be used to theoretically predict observations based on the TZ thickness of different reservoir rocks, using well-established formation evaluation methods. The novelty of our work stems from the ability of the model to theoretically and accurately predict the TZ thickness of the different lithostratigraphic units of hydrocarbon reservoirs, because of the experimental accessibility of its model parameters.

Abstract Toll-like receptor 9 (TLR-9) is a protein that helps our immune system identify specific DNA types. Upon detection, CpG oligodeoxynucleotides signal the immune system to generate cytokines, essential proteins that contribute to the body’s defence against infectious diseases. Native phosphodiester type B CpG ODNs induce only Interleukin-6 with no effect on interferon-α. We prepared silicon quantum dots containing different surface charges, such as positive, negative, and neutral, using amine, acrylate-modified Plouronic F-127, and Plouronic F-127. Then, class B CpG ODNs are loaded on the surface of the prepared SiQDs. The uptake of ODNs varies based on the surface charge; positively charged SiQDs demonstrate higher adsorption compared to SiQDs with negative and neutral surface charges. The level of cytokine production in peripheral blood mononuclear cells was found to be associated with the surface charge of SiQDs prior to the binding of the CpG ODNs. Significantly higher levels of IL-6 and IFN-α induction were observed compared to neutral and negatively charged SiQDs loaded with CpG ODNs. This observation strongly supports the notion that the surface charge of SiQDs effectively regulates cytokine induction.

The capability of dielectric measurements was significantly increased with the development of capacitive one-side access physical sensors. Complete samples give no opportunity to study electric susceptibility at a partial coverage of the one-side access sensor's active area; therefore, partial samples are proposed. The electric susceptibility at the partial coverage of a circular one-side access sensor with cylinders and shells is investigated for polyurethane materials. The implementation of the relative partial susceptibility permitted us to transform the calculated susceptibility data to a common scale of 0.0–1.0 and to outline the main trends for PU materials. The partial susceptibility, relative partial susceptibility, and change rate of relative partial susceptibility exhibited dependence on the coverage coefficient of the sensor's active area. The overall character of the curves for the change rate of the relative partial susceptibility, characterised by slopes of lines and the ratio of the change rate in the centre and near the gap, corresponds with the character of the surface charge density distribution curves, calculated from mathematical models. The elaborated methods may be useful in the design and optimization of capacitive OSA sensors of other configurations of electrodes, independent of the particular technical solution. [ABSTRACT FROM AUTHOR]

The study was aimed at formulating temozolomide (TMZ) loaded gelatin nanoparticles (GNPs) encapsulated into polyvinyl alcohol (PVA) nanofibers (TMZ–GNPs–PVA NFs) as the nano-in-nanofiber delivery system. The secondary objective was to explore the sustained releasing ability of this system and to assess its enhanced cellular uptake against U87MG glioma cells in vitro. Nano-in-nanofibers are the emerging drug delivery systems for treating a wide range of diseases including cancers as they overcome the challenges experienced by nanoparticles and nanofibers alone. The drug-loaded GNPs were formulated by one-step desolvation method. The Design of Experiments (DoE) was used to optimize nanoparticle size and entrapment efficiency. The optimized drug-loaded nanoparticles were then encapsulated within nanofibers using blend electrospinning technique. The U87MG glioma cells were used to investigate the uptake of the formulation. A 32 factorial design was used to optimize the mean particle size (145.7 nm) and entrapment efficiency (87.6%) of the TMZ-loaded GNPs which were subsequently ingrained into PVA nanofibers by electrospinning technique. The delivery system achieved a sustained drug release for up to seven days (in vitro). The SEM results ensured that the expected nano-in-nanofiber delivery system was achieved. The uptake of TMZ–GNPs–PVA NFs by cells was increased by a factor of 1.964 compared to that of the pure drug. The nano-in-nanofiber drug delivery system is a potentially useful therapeutic strategy for the management of glioblastoma multiforme. [ABSTRACT FROM AUTHOR]

Toll-like receptor 9 (TLR-9) is a protein that helps our immune system identify specific DNA types. Upon detection, CpG oligodeoxynucleotides signal the immune system to generate cytokines, essential proteins that contribute to the body's defence against infectious diseases. Native phosphodiester type B CpG ODNs induce only Interleukin-6 with no effect on interferon-α. We prepared silicon quantum dots containing different surface charges, such as positive, negative, and neutral, using amine, acrylate-modified Plouronic F-127, and Plouronic F-127. Then, class B CpG ODNs are loaded on the surface of the prepared SiQDs. The uptake of ODNs varies based on the surface charge; positively charged SiQDs demonstrate higher adsorption compared to SiQDs with negative and neutral surface charges. The level of cytokine production in peripheral blood mononuclear cells was found to be associated with the surface charge of SiQDs prior to the binding of the CpG ODNs. Significantly higher levels of IL-6 and IFN-α induction were observed compared to neutral and negatively charged SiQDs loaded with CpG ODNs. This observation strongly supports the notion that the surface charge of SiQDs effectively regulates cytokine induction. [ABSTRACT FROM AUTHOR]

Heavy metals are easily absorbed by living things because of their high-water solubility. Adsorption is a popular separation technique that is used to remove heavy metals from water since it is inexpensive, widely available, and ecologically benign. Chitosan's structure includes hydroxyl and amino groups, which make it a popular adsorbent for heavy metals. In this study, quaternization was used to change chitosan and improve its adsorption capacity. As the quaternizing agent, hexadecyltrimethylammonium bromide (TMAB) was employed. After blending the quaternized chitosan with polyvinyl alcohol and polysulfone, a membrane was created, and tetraethyl orthosilicate (TEOS) was used to crosslink it. Tetraethyl orthosilicate loadings of 1, 2, and 4 weight percent were added to the membrane formulation as a crosslinker. The surface morphology and surface charge of the prepared membranes were then described. Antifouling analysis and water permeation were used to test the performances. According to the results, membrane M4 with 4 weight percent TEOS exhibited the best characteristics, especially in terms of surface charge and surface morphology with strong antifouling capabilities. Furthermore, it has the highest water flux attributed to good surface hydrophilicity. The developed membranes may find application in the heavy metal removal phase of water treatment. [ABSTRACT FROM AUTHOR]

A recyclable activated carbon adsorbent with a highly negative surface charge was synthesized from bael fruit shell waste. The structural, morphological, and surface properties of the activated carbon adsorbent were evaluated using XRD, FE-SEM, FTIR, zeta potential, and BET surface area analysis. The results demonstrated that the surface area of the activated carbon adsorbent got significantly enhanced (944.09 m2/g) as compared to that of the carbonized material (2.43 m2/g) which was validated through FE-SEM analysis. The zeta potential value of activated carbon (− 16.2 mV) reveals that the net surface charge of the activated carbon is negative, which leads to 94.15% removal of methylene blue dye (cationic) as compared to 65.71% and 50.59% removal of rhodamine B (zwitterionic) and reactive red (anionic) dyes, respectively. This could be due to the electrostatic attraction between the cationic methylene blue dye and the negative surface of activated carbon. Furthermore, the adsorption data revealed that 300 mg of activated carbon, 50 ppm initial concentration, and pH of 6.56 are the optimum conditions for enhanced adsorption capacity of activated carbon towards methylene blue pollutant. The adsorption experimental data were best fitted into the Langmuir isotherm and second-order kinetic model (R2 = 0.99–1.00). In addition, the activated carbon was successfully regenerated and reused up to 5 cycles of adsorption experiments where the adsorption efficiency was retained. Therefore, the bael fruit shell waste–derived activated carbon adsorbent with a high negative surface charge could be a potential alternative to commercial counterparts in the selective removal of pollutants removed from the wastewater stream. [ABSTRACT FROM AUTHOR]

The possibility of utilizing technical pyrocarbon, produced by the pyrolysis of used automobile tires, in a composite suspension fuel is demonstrated. It has been found that pyrocarbon-based systems without additives are not suitable for use as fuel due to thickening and hydrophobic properties. To improve the properties of the composite suspension fuels, the influence of stabilizer, plasticizer, and dispersant additives on the rheological properties of the composite suspension fuel was investigated. Carboxymethyl cellulose, sodium lignosulfonate, NF, C-3 (a condensation product of β-naphthalene sulfonic acid and formaldehyde), and humic acids were used as additives. It was determined that the surface of unmodified pyrocarbon has a positive surface charge in the pH range of 2-10. Addition of reagents induces a change in the surface charge of pyrocarbon and surface recharging. It is shown that the best results in composite suspension fuel compositions are achieved with the addition of C-3 at a concentration of 2 wt.%. The effective viscosity of the obtained suspensions at a shear rate of 9 s-1 does not exceed 0.8 Pa⋅s. This allows the use of the obtained systems with additives as liquid suspension fuels. [ABSTRACT FROM AUTHOR]

The creations and manipulations of vortexes in ferroelectric materials with external stimuli are expected to be used in the design and fabrication of sensing materials and multifunctional electronic devices. In this work, we investigated the surface charge-induced multi-vortex evolution using the phase-field simulations in BiFeO3. A combination of domain morphology, polarization distribution and winding number calculation was considered. The results show that vortex and anti-vortex exist simultaneously in pairs, and the total value of winding numbers is always 0. In addition, the minimum distance Δ l between the surface charge regions is 9 nm when the vortex domains are independent of each other. This work provides a reference for the manipulation of ferroelectric vortex induced by surface charges, which lays a theoretical foundation for the design and fabrication of high-density vortex memories. [ABSTRACT FROM AUTHOR]

The two‐dimensional (2D) MXenes with sufficient interlayer spacing are promising cathode materials for aluminum‐ion batteries (AIBs), yet the electrostatic repulsion effect between the surface negative charges and the active anions (AlCl4−) hinders the intercalation of AlCl4− and is usually ignored. Here, we propose a charge regulation strategy for MXene cathodes to overcome this challenge. By doping N and Co, the zeta potential is gradually transformed from negative (Ti3C2Tx) to near‐neutral (Ti3CNTx), and finally positive (Ti3CNTx@Co). Therefore, the electrostatic repulsion force can be greatly weakened between Ti3CNTx and AlCl4−, or even formed a strong electrostatic attraction between Ti3CNTx@Co and AlCl4−, which can not only accommodate more AlCl4− ions in the Ti3CNTx@Co interlayers to increase the capacity, but also solve the stacking and expansion problems. As a result, the optimized Al‐MXene battery exhibits an ultrahigh capacity of up to 240 mAh g−1 (2–4 times the capacity of graphite cathode, 60–120 mAh g−1) and a potential ultrahigh energy density (432 Wh kg−1, 2–4 times the value of graphite, 110–220 Wh kg−1) based on the mass of cathode materials, comparable to LiFePO4‐based lithium‐ion batteries (350–450 Wh kg−1, based on the mass of LiFePO4). [ABSTRACT FROM AUTHOR]

The proliferation of urbanization and the integration of new energy sources have stimulated the development of gas-insulated transmission lines and switchgear (GIL/GIS). In particular, the compact DC GIS in offshore converter platforms will significantly reduce footprints for DC switchyards, exhibit exceptional climatic resistance, and facilitate the cost-effective connection of remote offshore wind farms and submarine links. Nevertheless, insulators used in GIS/GIL always suffer from surface charge accumulation under DC stress, which could distort and enhance the local electric field and thus trigger a flashover at the gas–solid interface if it exceeds certain magnitude levels. This susceptibility becomes a major concern affecting the reliability of DC gas-insulated systems. Beyond these engineering-related challenges lie fundamental physics problems involving mechanisms of charge accumulation and charge-induced flashover which still require exploration. To this end, this paper presents an overview of recent advancements on this topic whilst highlighting relevant issues to be addressed. Specifically, the surface charge accumulation phenomena under DC fields are reviewed, and the charging mechanisms are summarized from macroscopic to microscopic perspectives. Further, the correlation between surface charge and surface flashover is discussed. Moreover, recent developments in tailoring methods for surface charging are also presented. Finally, perspectives are given on current research progress and future needs. [ABSTRACT FROM AUTHOR]

Abstract Solid‐state nanopore sensors, a type of resistive pulse sensing, achieve optimal signal‐to‐noise performance with a single nanopore. However, the processes involved in solid‐state nanopore fabrication and subsequent measurements frequently lead to the formation of multiple nanopores, posing a challenge for precise detection. To address this issue, here, a novel and expedient technique to verify the presence of a single nanopore on a chip is developed. The methodology includes measuring the nanopore's conductance in solutions of various salt conditions, followed by a comparison of these results against a theoretical conductance model. This comparison is instrumental in distinguishing between single and multiple nanopores. Additionally, the study delves into various factors that influence the conductance curve, such as deviations in pore shape from the standard circle and inconsistencies in pore diameter. This approach significantly enhances the practical application of low‐cost nanopore preparation techniques, particularly in scenarios like controlled breakdown nanopore fabrication, where the formation of multiple nanopores is a common concern.

Abstract Ionic FETs have enormous potential for energy conversion, sensing, and ionic circuits due to their efficient regulation of the nanochannel. Here ionic FETs based on single‐crystal silicon nanopores and the rectification of the fabricated devices are studied. The electrical characterization results demonstrated that since the silicon‐based nanopores have the advantage of modulating the surface charge due to their semiconductor nature and benefitting from the effective 3D gating effect on the nanochannel, the magnitude and polarity of surface charge can be modulated by the gate voltage. The rectification effect can be adjusted by applying a certain voltage and fulfilling a transition between anion selectivity and cation selectivity when the surface charge polarity is reversed. Moreover, current–voltage characteristics of the reported ionic FET can be switched between ohmic and diode‐like regimes. The proposed ionic FETs supply a novel platform to study the ionic properties and have great potential to be applied in large‐scale ionic circuits due to their excellent performance. Finally, simulation results prove the surface charge modulated by the gate voltage determines the magnitude and direction of rectification, which is consistent with the reported experiment result.

Metal particle and air gap defects on the surface of insulators can induce localized electric field distortions and exacerbate charge accumulation, subsequently triggering surface flashover. In this study, we first enhanced traditional capacitive probes to improve stability and effectively suppress charge leakage. The modified probes achieved a charge leakage time constant exceeding 5600 s, with a leakage amount of only 4.9% over a single data acquisition period (210 s). Based on this improvement, we developed a system for measuring surface charges on insulators, investigating the characteristics and influencing factors of surface charge accumulation under metal micro-particles and air gap defects. The results demonstrate that metal micro-particles adhering to the insulator surface accumulate charges of opposite polarity at different locations under applied voltage. These charges tend to diffuse over time and with increased voltage. The presence of air gap defect accelerates charge accumulation in its vicinity, with charge polarity and location being closely related. When the air gap is near the high-voltage electrode, the insulator surface predominantly accumulates positive charges. Conversely, when the air gap is near the ground electrode, negative charges accumulate at both the high-voltage and ground electrodes, with positive charge accumulating in the central region. Both the amplitude and duration of the applied voltage affect the charge accumulation on the air gap surface. Interestingly, with prolonged voltage application, the surface positive charge density in the air gap decreases. Different defect models exhibit charge inversion phenomena occur as the voltage amplitude increases.

PCB layouts with different polygon shapes and insulation distances were prepared and their surface flashover voltage subjected to different ramping rates were measured at different temperatures and different low gas pressures for emulated high-altitude conditions. The dependence of the surface flashover voltage on effects of gas pressure, surface insulation distance, temperature, and polygon shape was studied. Modulation efforts which include tailoring the local surface conductivity and local topography modification were performed to increase the flashover of PCB, and the related mechanism was studied. The results showed that the voltage ramping rate plays an important role in determining flashover voltage. The flashover voltage is lower when the sample is subjected to a rapid voltage ramping rate than with a slow ramping rate. This phenomenon is more prominent towards ambient pressure. The increase in temperature results in a decrease in flashover voltage at 100 kPa, while at 20 kPa and 10 kPa, the influence of temperature on flashover becomes less significant. Through-holes designed in the PCB have a positive role in increasing flashover voltage at lower pressures. However, at 100 kPa, the holes no longer contribute to any higher flashover voltage. Modification of local surface conductivity has no contribution in increasing the flashover voltage, while a surface coating with a surface conductivity of $10^{-10}$ S dramatically decreases the flashover voltage. The work presented in this paper provides a reference for the design and modification of PCB layouts for use in future aerospace hybrid propulsion systems.

To identify a nanocomposite material capable of mitigating surface charge accumulation issues in silicone rubber composite insulators, this paper investigated the surface charge dissipation characteristics of micron-sized Al2O3/silicone rubber composites with different weight percentages under positive dc voltage. Furthermore, this paper investigated the influence of the uncharged and charged silicone rubber on the surface flashover voltage under positive dc voltage. The result show that the addition of micron-sized Al2O3 particles effectively ameliorates the severity of surface charge accumulation. In comparison to pure silicone rubber, the reduction in maximum surface charge density and average surface charge density of different weight percentage Al2O3/silicone rubber composites ranges from 18.60% to 50.60% and from 33.26% to 57.53%, respectively. When there is no surface charge on the silicone rubber surface, the addition of micron-sized Al2O3 particles at different weight percentages results in a decrease in positive dc surface flashover voltage. Conversely, when a positive surface charge is applied to the silicone rubber surface, the greatest reduction in positive dc surface flashover voltage occurs in pure silicone rubber. Furthermore, the positive DC flashover voltage of pure silicone rubber can recover to 86.53% of its value without applied surface charge at a decay time of 60 minutes. In contrast, the addition of micron-sized Al2O3 particles at different weight percentages diminishes the impact of surface charge on the surface flashover voltage, allowing it to recover to 92.03% to 94.18% of its value without applied surface charge.

The study presents the electrokinetic properties of the zeta potential and the isoelectric point for cellulose diacetate (CA) in the forms of powder, nonporous film, and porous film. Surface zeta potential (ζ) and isoelectric point (IEP) are important properties that reflect the material's behavior in contact with liquids, as a consequence of the surface charge density and the morphology of the material. Nonporous films are prepared by casting CA solution on glass and Teflon dishes, while the porous film is prepared by the solution blow spinning (SBS) technique. The ζ potential is determined using the streaming potential method in the pH range from 2.5 to 9.5. The influence of the material's crystallinity (CI) and surface roughness (Sa) on the zeta potential is studied. The form of the material (powder, porous film, or nonporous film) influences the electrokinetic properties, which may have consequences on their behavior in contact with liquid (e.g., for processes such as oxidation, surface modification, grafting, or aging during use). [ABSTRACT FROM AUTHOR]

The application of binary gas mixtures consisting of heptafluorobutyronitrile (C4F7N) and carbon dioxide (CO2) in AC GIS is currently attracting much attention. Therefore, the evaluation of the gas–solid interface charge distribution characteristics of epoxy resin is indispensable. Additionally, the phase-dependency of the charging behavior remains not fully understood. We simulated coaxial electrode structure in GIS and investigated the surface charge distribution on a down-scaled epoxy insulator. The influence of the truncated phase angle and duration of AC voltage on charge behavior were analyzed, and the charge transport mechanism under AC voltage was theoretically analyzed. The results showed that there was a noticeable negative charge speckle with the presence of the metal particle and the accumulated negative charge on the insulator surface far exceeded that of the positive charge. The maximum surface charge density and the amount of surface charge accumulated first increased and then decreased over time. It was found that the phase angle has a negligible influence on the surface charge distribution at the cut-off moment.

Tissue engineering is an interdisciplinary field of science that has been developing very intensively over the last dozen or so years. New ways of treating damaged tissues and organs are constantly being sought. A variety of porous structures are currently being investigated to support cell adhesion, differentiation, and proliferation. The selection of an appropriate biomaterial on which a patient's new tissue will develop is one of the key issues when designing a modern tissue scaffold and the associated treatment process. Among the numerous groups of biomaterials used to produce three-dimensional structures, hydroxyapatite (HA) deserves special attention. The aim of this paper was to discuss changes in the double electrical layer in hydroxyapatite with an incorporated boron and strontium/electrolyte solution interface. The adsorbents were prepared via dry and wet precipitation and low-temperature nitrogen adsorption and desorption methods. The specific surface area was characterized, and the surface charge density and zeta potential were discussed. [ABSTRACT FROM AUTHOR]

Porous starch can be applied as an adsorbent and encapsulant for bioactive substances in the food and pharmaceutical industries. By using appropriate modification methods (chemical, physical, enzymatic, or mixed), it is possible to create pores on the surface of the starch granules without disturbing their integrity. This paper aimed to analyze the possibility of obtaining a porous structure for native corn, potato, and pea starches using a combination of ultrasound, enzymatic digestion, and freeze-drying methods. The starch suspensions (30%, w/w) were treated with ultrasound (20 kHz, 30 min, 20 °C), then dried and hydrolyzed with amyloglucosidase (1000 U/g starch, 50 °C, 24 h, 2% starch suspension). After enzyme digestion, the granules were freeze-dried for 72 h. The structure of the native and modified starches were examined using VIS spectroscopy, SEM, ATR-FTIR, and LTNA (low-temperature nitrogen adsorption). Based on the electrophoretic mobility measurements of the starch granules using a laser Doppler velocimeter, zeta potentials were calculated to determine the surface charge level. Additionally, the selected properties such as the water and oil holding capacities, least gelling concentration (LGC), and paste clarity were determined. The results showed that the corn starch was the most susceptible to the combined modification methods and was therefore best suited for the production of porous starch. [ABSTRACT FROM AUTHOR]

Titania (TiO2) nanosheets are crystals with controlled, highly ordered structures that improve the functionality of conventional TiO2 nanoparticles. Various surface modification methods have been studied to enhance the effectiveness of these materials as photocatalysts. Surface modifications using electrical polarization have attracted considerable attention in recent years because they can improve the function of titania without changing its composition. However, the combination of facet engineering and electrical polarization has not been shown to improve the functionality of TiO2 nanosheets. In the present study, the dye-degradation performance of polarized TiO2 nanosheets was evaluated. TiO2 nanosheets with a F/Ti ratio of 0.3 were synthesized via a hydrothermal method. The crystal morphology and structure were evaluated using transmission electron microscopy and X-ray diffraction. Then, electrical polarization was performed under a DC electric field of 300 V at 300 °C. The polarized material was evaluated using thermally stimulated current measurements. A dye-degradation assay was performed using a methylene blue solution under ultraviolet irradiation. The polarized TiO2 nanosheets exhibited a dense surface charge and accelerated decolorization. These results indicate that electrical polarization can be used to enhance the photocatalytic activity of TiO2. [ABSTRACT FROM AUTHOR]

The self-consistent propagation of electrical impulses and of the accompanying distortions of the electron surface in the framework of a cold plasma model with a sharp boundary has been described with help of a derived system of two equations. The method of 'shallow water theory' has been applied for the case of bounded plasma and deriving an equation with which to link the spatial and temporal structures and evolution of the boundary curvature and the surface charge. Under certain conditions, such perturbations can propagate along the boundary without changing their shape for a long distance. An approximate analytical solution has been found, and numerical calculations have been performed. Mutual connections between basic parameters of the considered perturbations (velocity components, electrostatic field, etc.) have been presented. [ABSTRACT FROM AUTHOR]

Harvesting clean energy from water evaporation has been extensively investigated due to its sustainability. To achieve high efficiency, energy conversion materials should contain multiple features which are difficult to be simultaneously obtained from single-component materials. Here we use composite laminar membranes assembled by nanosheets of graphene oxide and mica, and find a sustained power density induced by water evaporation that is two orders of magnitude larger than that from membranes made by either of the components. The power output is attributed to selective proton transport driven by water evaporation through the interlayer nanochannels in the membranes. This process relies on the synergistic effects from negatively charged and hydrophilic mica surfaces that are important for proton selectivity and water transport, and the tunable electrical conductivity of graphene oxide that provides optimized internal resistance. The demonstrated composite membranes offer a strategy of enhancing power generation by combining the advantages from each of their components. [ABSTRACT FROM AUTHOR]