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In this research, the influence and comparison of ultrasonic and microwaves on the wettability of carbonate rock have been investigated. Wettability is one of the most fundamental parameters of the oil reservoir, according to which the fluid movement in the porous medium can be examined. The aged thin sections were placed in a microwave oven and an ultrasonic bath and they were exposed to radiation for 2-10 minutes. Using the contact angle analysis, it was observed that the angle between the rock and oil drop of microwaved and ultrasonicated samples changed by 57 and 71 degrees, respectively. Contact angle and temperature changes started faster for the ultrasonicated samples. The surface charge of the rocks was determined by zeta potential analysis, and it was found that in both samples, in the first minutes of radiation, negatively charged colloids were liberated from the samples by absorbing the waves, which reduced the surface negative charges, and with the continued radiation, positively charged colloids were decreased due to the evaporation of light oil compounds. The reduction of zeta potential occurred faster for the ultrasonicated sample, but the rate of decrease was lower. By examining Fourier-transform infrared spectroscopy (FTIR) results, it was concluded that the heavy compounds on the surface of the samples were cracked and turned into lighter hydrocarbons, and the changes for both samples were almost equal. Also, the polar compounds, sulfur, and nitrogen in samples increased, decreased, and decreased respectively for both samples, and these changes were more for the ultrasonicated samples.

The construction of the future energy structure of China under the 2050 carbon-neutral vision requires compact direct current (DC) gas-insulation equipment as important nodes and solutions to support electric power transmission and distribution of long-distance and large-capacity. This paper reviews China's 10-year progress in DC gas-insulated equipment. Important progresses in basic research and industry perspective are presented, with related scientific issues and technical bottlenecks being discussed. The progress in DC gas-insulated equipment worldwide (Europe, Japan, America) is also reported briefly.

Jie Zhou,1,2 Hongjin Xiang,1,2 Jianbo Huang,1,2 Yi Zhong,3 Xiaoxia Zhu,1,2 Jinshun Xu,1,2 Qiang Lu,1,2 Binyang Gao,1,2 Huan Zhang,1,2 Rui Yang,1,2 Yan Luo,1,2 Feng Yan1,2 1Ultrasound Department, West China Hospital of Sichuan University, Chengdu, People’s Republic of China; 2Laboratory of Ultrasound Imaging, West China Hospital of Sichuan University, Chengdu, People’s Republic of China; 3Laboratory of Mitochondria and Metabolism, West China Hospital of Sichuan University, Chengdu, People’s Republic of ChinaCorrespondence: Feng Yan, Laboratory of Ultrasound Imaging, West China Hospital of Sichuan University, Chengdu, People’s Republic of China, Tel/Fax +86 028 8516 4146, Email yan_feng@scu.edu.cn Yan Luo, Ultrasound Department, West China Hospital of Sichuan University, Chengdu, People’s Republic of China, Tel/Fax +86 028 8542 3192, Email yanluo@scu.edu.cnPurpose: To prepare nanoscale ultrasound contrast agents (Nano-UCAs) and examine the role of their surface charge in complement activation and phagocytosis.Materials and Methods: We analyzed serum proteins present in the corona formed on Nano-UCAs and evaluated two important protein markers of complement activation (C3 and SC5b-9). The effect of surface charge on phagocytosis was further assessed using THP-1 macrophages.Results: When Nano-UCAs were incubated with human serum, they were opsonized by various blood proteins, especially C3. Highly charged Nano-UCAs, whether positive or negative, were favorably opsonized by complement proteins and phagocytized by macrophages.Conclusion: Charged Nano-UCAs show a higher tendency to activated complement system, and are efficiently engulfed by macrophages. The present results provide meaningful insights into the role of the surface charge of nanoparticles in the activation of the innate immune system, which is important not only for the design of targeted Nano-UCAs, but also for the effectiveness and safety of other theranostic agents.Graphical Abstract: Keywords: nanoscale ultrasound contrast agents, surface charge, protein corona, complement activation, opsonization, phagocytosis

Introduction. For the last decade, nanotechnology has been studied extensively in the pharmaceutical field. Among all the nanotechnology formulation areas, nanostructured lipid carrier is enormously researched by formulation scientists as it is one of the focused areas of lipid carrier for the effective formulation.Materials and methods. The nanostructured lipid carrier (NLC) consists of solid lipid, liquid lipid & surfactant for fabrication of formulation. Methods such as high energy methods, low energy methods and organic solvent-based methods are used for the preparation of NLC. As per literature study the High pressure homogenization is the most efficient method for fabrication of formulation.Results and discussion. This carrier system has significant advantages such as high drug entrapment, improved bioavailability, stability during storage, and targeting the site with a better-controlled release making it a prominent area for the formulator to emphasize on it. Although many drugs are formulated with a nanostructured lipid carrier, it is a concern for researchers to find out the effectiveness of formulation by studying the process parameter and safety.Conclusion. The present review was focused to study the impact of various parameters such as Lipid, surfactant, homogenization rate, preservative, Crystallinity, and surface charge on the formulation. The study also extended towards toxicity and biocompatibility, topical targeting & cancer treatment of the Nanostructured lipid carrier.

The sorption mechanism of hexavalent chromium sorption on eucalyptus barks was evaluated as a function of solution pH for different adsorbent dosages, surface coverage, and the amount of adsorbent. The chromium retention was evaluated based on the distribution coefficient (D), and this retention is attributed to species, which is predominant between pH 1 and 6.5. The biosorption of Cr(VI) ions onto barks achieved at pH 2.0 in the highest sorbet conditions corresponding to [Cr(VI)] = 10–5 mol (V = 100 mL) is examined for various surface coverage. The surface complexes formed between chromate and eucalyptus barks were found to be > S (HCrO4) and > S (CrO4). Logarithmic stability for log K1–1 and the log K10 values of the complexes were measured and found to be -5.93 in acidic medium and -0.76 in alkaline medium, respectively. Pointed out that the adsorption of Cr(VI) on eucalyptus bark was greater than 90% in all cases, Cr(VI) recovery is strongly acidic dependent and shows maximum retention, for various sorbent amounts, at pH around 2, and this retention is attributed to species, which is predominant between pH 1 and 6.5, the morphological surface of eucalyptus barks were examined by Scanning Electron Microscope (SEM) connected to a micro analyzer EDS.

The magnitude of surface charges and points of zero charge in water-clay suspensions with pH equal to 5, 7, and 9 were studied. Their changes on exposure to a microwave field and variations in the dispersity of particles were determined. Powders of two fractions of montmorillonite, polymineral, and kaolin clays of the Orenburg Oblast were chosen as the objects of investigation. The points of zero charge (PZC) of the indigenous clays were determined by means of weight titration, based on measuring the value of the limiting pH with an increase in the weight fractions of the clay. Processing of clay powders in a microwave field was conducted according to the following regime: output power 750 W, operating frequency 2.45 GHz, and exposure time 600 sec. The magnitude and sign of the charges formed at the interface between the particle surface and the electrolyte solution depend on the mineralogical composition of the particles. Finely dispersed fractions of two clays turned out to be sensitive to processing in a microwave field — montmorillonite-containing and polymineral; pH indicators of PZC shifted to the acidic region by 0.26 and 0.31, respectively (by 4%). The pH values of the PZC suspensions with kaolin clay after treatment in microwave radiation remained practically unchanged. If the pH of the solution surrounding the particle exceeds the pH of PZC, then the sorbent will be able to absorb cations; if the pH of the solution is below the pH of PZC, then anions are absorbed. The results obtained will make it possible to use microwaves as a tool for expanding pH range and thereby promoting efficient sorption of anions and cations. [ABSTRACT FROM AUTHOR]

With the extensive application of glass fiber reinforced polymer (GFRP) in the field of high voltage insulation, its operating environment is becoming more and more complex, and the surface insulation failure has gradually become a pivotal problem affecting the safety of equipment. In this paper, nano-SiO2 was fluorinated by Dielectric barrier discharges (DBD) plasma and doped with GFRP to enhance the insulation performance. Through Fourier Transform Ioncyclotron Resonance (FTIR) and X-ray Photoelectron Spectroscopy (XPS) characterization of nano fillers before and after modification, it was found that plasma fluorination can graft a large number of fluorinated groups on the surface of SiO2. The introduction of fluorinated SiO2 (FSiO2) can significantly enhance the interfacial bonding strength of the fiber, matrix and filler in GFRP. The DC surface flashover voltage of modified GFRP was further tested. The results show that both SiO2 and FSiO2 can improve the flashover voltage of GFRP. When the concentration of FSiO2 is 3%, the flashover voltage increases most significantly to 14.71 kV, which is 38.77% higher than that of unmodified GFRP. The charge dissipation test results show that the addition of FSiO2 can inhibit the surface charge migration. By the calculation of Density functional theory (DFT) and charge trap, it is found that grafting fluorine-containing groups on SiO2 can increase its band gap and enhance its electron binding ability. Furthermore, a large number of deep trap levels are introduced into the nanointerface inside GFRP to enhance the inhibition of secondary electron collapse, thus increasing the flashover voltage. [ABSTRACT FROM AUTHOR]

Micro/nanoparticles are widely used as useful biosensing platforms. Molecular recognition efficiently occurs on their surface, where ligand molecules are accumulated and, in some cases, well organized. The interactions that occur on or in the micro/nanoparticle significantly alter its physicochemical properties. Therefore, highly sensitive detection is possible based on such changes. Usual biosensors convert molecular or biological responses into optical or electrochemical signals. Particle-based biosensing can utilize a variety of other transducing mechanisms, including the changes in the levitation position of particles in physical fields, diffusion behavior, aggregation or dissociation, changes in the surface charge, and changes in size. We review the recent developments in biosensing based on various aspects of particle behavior. [ABSTRACT FROM AUTHOR]

Insulation cellulose paper is a basic measure for a power transformer's remaining useful life, and its advantageous low cost, electrical, and mechanical properties have made it an extensive insulation system when impregnated in a dielectric liquid. Cellulose paper deteriorates as a result of ageing due to some chemical reactions like pyrolysis (heat), hydrolysis (moisture), and oxidation (oxygen) that affects its degree of polymerization. The condition analysis of cellulose paper has been a major concern since the collection of paper samples from an operational power transformer is almost impossible. However, some chemicals generated during cellulose paper deterioration, which were dissolved in dielectric liquid, have been used alternatively for this purpose as they show a direct correlation with the paper's degree of polymerization. Furthermore, online and non-destructive measurement of the degree of polymerization by optical sensors has been proposed recently but is yet to be available in the market and is yet generally acceptable. In mitigating the magnitude of paper deterioration, some ageing assessments have been proposed. Furthermore, researchers have successfully enhanced the insulating performance of oil-impregnated insulation paper by the addition of various types of nanoparticles. This study reviews the ageing assessment of oil-paper composite insulation and the effect of nanoparticles on tensile strength and electrical properties of oil-impregnated paper insulation. It includes not only significant tutorial elements but also some analyses, which open the door for further research on the topic. [ABSTRACT FROM AUTHOR]

Trees have been used for phytoremediation and as biomonitors of air pollution. However, the mechanisms by which trees mitigate nanoparticle pollution in the environment are still unclear. We investigated whether two important tree species, European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.), are able to take up and transport differently charged gold nanoparticles (Au-NPs) into their stem by comparing leaf-to-root and root-to-leaf pathways. Au-NPs were taken up by roots and leaves, and a small fraction was transported to the stem in both species. Au-NPs were transported from leaves to roots but not vice versa. Leaf Au uptake was higher in beech than in pine, probably because of the higher stomatal density and wood characteristics of beech. Confocal (3D) analysis confirmed the presence of Au-NPs in trichomes and leaf blade, about 20–30 μm below the leaf surface in beech. Most Au-NPs likely penetrated into the stomatal openings through diffusion of Au-NPs as suggested by the 3D XRF scanning analysis. However, trichomes were probably involved in the uptake and internal immobilization of NPs, besides their ability to retain them on the leaf surface. The surface charge of Au-NPs may have played a role in their adhesion and uptake, but not in their transport to different tree compartments. Stomatal conductance did not influence the uptake of Au-NPs. This is the first study that shows nanoparticle uptake and transport in beech and pine, contributing to a better understanding of the interactions of NPs with different tree species. [ABSTRACT FROM AUTHOR]

Prevention of encrustation on the surface has always been the biggest challenge for urological implants. In the field of ureteral stent design, biodegradability has attracted much attention in recent years, because biodegradable ureteral stents not only avoid secondary intervention, but also prevent encrustation due to surface renewal by degradation process. Furthermore, researches have focus on some surface parameters to provide guidance for the development of stent materials, such as hydrophilicity or surface charge. In this work, we synthesized two types of poly(ester-carbonate)s, poly(L-lactide-co-5-amino-1,3-dioxan-2-one) (P(LA-co-AC)) containing amino, and poly (L-lactide-co-5-methyl-5-carboxyl-1,3-dioxan-2-one) (P(LA-co-MCC)) containing carboxyl. Blending P(LA-co-AC) and P(LA-co-MCC) with poly(L-lactide-co-Ɛ-caprolactone) (PLACL) respectively, two types of ureteral stent materials were prepared. Due to the influence of ions formed by the dissociation of amino and carboxyl, two types of materials show differences in surface charge analyses. We further developed a dynamic urinary extracorporeal circulation (DUEC) system to assess in vitro encrustation of materials with different surface charges. The results of this comparative study identified that the materials with strong negative surface charge were most favorable for use as ureteral stent, and provided a new approach to surmount the problems faced by urological surgery which complied with the future trend of biodegradable ureteral stent design. [ABSTRACT FROM AUTHOR]

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Surface charges on implants improve integration into bone and so require a clear protocol for achieving a surface charge and comparable results from different laboratories. This study sintered hydroxyapatite (HAp) at one laboratory to remove the influence of the microstructure on surface charge and then polarized/depolarized the pellets at two different laboratories (in Tokyo and Riga). Surface charges on HAp pellets induced by electric polarization at 400 °C in a 5 kV/cm DC electric field were measured by the thermally stimulated depolarization current (TSDC) method as 6–9 µC/cm2. The surface charge results were comparable between laboratories and also agreed with previously documented values. Recommendations describe conditions for polarization and depolarization to generate a surface charge and repeatedly achieve a comparable outcome. A visual display of the polarization mechanisms and the contribution to surface charge point to further aspects that need further development. [ABSTRACT FROM AUTHOR]

The charge accumulation phenomenon at the gas–solid interface under the co-action of DC electric field and temperature gradient is of great significance, but its long-time evolution characteristics are still unclear. In this work, the accumulation and dissipation characteristics of the surface charge on the epoxy-SF6 interface within 216 h were obtained, indicating that, (a) the normal surface electric field is increased by the temperature gradient along the gas–solid interface, which results in a prominent increase in the surface charge density; (b) there are different evolution processes of surface charge in high and low temperature regions under the co-action of DC-temperature gradient, and the increase of the charge trap density caused by the degradation of solid material is considered to be an important reason for the charge evolution; (c) the total charge dissipation ratio within 600 s decreases with the increase of charging time in DC electric field, and the surface charge dissipates mainly to the gas side of the interface; (d) the large amount of charge accumulated at the interface distorts the surface electric field at the triple junction points. The total electric field strength at the low-temperature tri-junction point increases by 35.5%, while the direction of the tangential field at the high-temperature tri-junction point reverses during the long-time co-action of the DC-temperature gradient. The results of this work may be helpful to understand the long-time charge evolution characteristics of the gas–solid interface under the DC-temperature gradient and to reveal the failure mechanism of the gas–solid interface. [ABSTRACT FROM AUTHOR]

Electrochemical biosensors based on structure‐switching aptamers offer many advantages because they can operate directly in complex samples and offer the potential to integrate with miniaturized electronics. Unfortunately, these biosensors often suffer from cross‐reactivity problems when measuring a target in samples containing other chemically similar molecules, such as precursors or metabolites. While some progress has been made in selecting highly specific aptamers, the discovery of these reagents remains slow and costly. In this work, a novel strategy is demonstrated to distinguish molecules with miniscule difference in chemical composition (such as a single hydroxyl group)—with cross reactive aptamer probes—by tuning the charge state of the surface on which the aptamer probes are immobilized. As an exemplar, it is shown that the strategy can distinguish between DOX and many structurally similar analytes, including its primary metabolite doxorubicinol (DOXol). Then the ability to accurately quantify mixtures of these two molecules based on their differential response to sensors with different surface‐charge properties is demonstrated. It is believed that this methodology is general and can be extended to a broad range of applications. [ABSTRACT FROM AUTHOR]

High-voltage direct current (HVDC) links are starting to become widely implemented thanks to their interesting advantages such as reduced operation losses, the absence of reactive power, which allows energy transport via underground cables over long distances, and improved power control. The latter advantage is very essential for renewable energy resource integration into power grids. However, a thorough understanding of the behavior of insulation systems for HVDC components is critical so as to ensure a more reliable service. Indeed, the existence of the direct current (DC) voltage in HVDC components may induce surface and space charge accumulation that can stress insulation further or even promote discharge inception and propagation. As such, this work focuses on showcasing the effect of surface charge on streamers that develop on the interface of liquid–solid insulation due to the advent of lightning impulse (LI) voltage in the HVDC link. This study was performed using finite-element-based numerical simulations that include a quasi-electrostatic model for surface charge accumulation and an electrohydrodynamic fluid model for streamer initiation and propagation. The geometry used was point–plane configuration where the high voltage is applied to the needle electrode located above the liquid–solid interface. The obtained results suggest that streamer initiation is affected by both the accumulated surface charge density and polarity. For a positive streamer, an accumulation of positive surface charge increases the discharge inception voltage as a result of a weakening in the electric field, while an accumulation of negative surface charge decreases the discharge inception voltage due to an intensification in the electric field. Moreover, streamer travel distance and velocity are also both shown to be affected by surface charge accumulation. [ABSTRACT FROM AUTHOR]

Sorption characteristics of the acid-activated bauxite waste red-mud for Nylomine-Blue and Methylene-Blue were investigated to predict its potential removal ability for anionic-di-anthraquinone and cationic-thiazine-dyes, respectively. Surface characteristics of the red-mud were examined using atomic-force-microscopy, diffuse-reflectance-Fourier-transform, and X-ray-diffraction spectroscopy techniques. Kinetic data obtained at four different temperatures fit well to the pseudo-second-order and homogeneous-surface-diffusion models. The experimental Nylomine-Blue sorption capacity (0.020 mmol/g) is higher than that of Methylene-Blue (0.012 mmol/g) at 288 K but they change oppositely with the temperature and attain 0.013 and 0.043 mmol/g at 318 K, respectively. Experimental equilibrium data for Methylene-Blue and Nylomine-Blue are well predicted by the Freundlich, Langmuir, and Dubinin-Radushkevich isotherm equations. The mean-sorption-energies fall into the ion-exchange range for Methylene-Blue but electrostatic-attraction-forces play a more important role in Nylomine-Blue sorption. These mechanisms were correlated to the pH changes in the sorption process and the differences in the diffuse-reflectance-Fourier-transform spectra of dye-loaded sorbents. The atomic-force-microscopy topography and phase images revealed that the hematite and sodalite appear as hills on the red-mud surface but gibbsite and calcite minerals cover the valleys. The Methylene-Blue molecules are sorbed by ion-exchange in the positively-charged-valleys in dilute solutions but Nylomine-Blue is sorbed specifically on overall surface in whole concentration range. [ABSTRACT FROM AUTHOR]

Bioactive glasses (BGs) are promising for bone tissue regeneration. BG composition can be tailored, according to the application of interest, and/or functionalized with organic molecules/biomolecules to improve their performances. However, despite the wide knowledge concerning BGs, their interaction with proteins, fundamental for controlling the fate of the implant, has not been deeply investigated yet. Controlling or predicting protein adsorption requires a full understanding of the materials surface physico-chemical properties. In this work, four different BGs (S53P4, B25, SCNB, PhGlass) were surface-modified by four different treatments: 72 h-soaking in TRIS, 72 h soaking in simulated body fluid, APTES grafting and quaternized APTES grafting. The surfaces were then characterized both untreated and after each treatment by contact angle, zeta potential analysis, X-ray photoelectron spectroscopy, Fourier Transform InfraRed–Attenuated Total Reflectance spectroscopy and Scanning Electron Microscopy and Energy Dispersive Spectroscopy. Inductively Coupled Plasma – Optical Emission Spectrometry was then performed to investigate the ion leaching. The aim of this study (Part I) is the physico-chemical characterization of BGs as a function of the implemented treatments, aiming to better understand how the superficial properties are successively affecting protein adsorption. Protein adsorption on untreated and treated BGs will be discussed in a following manuscript (Part II). [ABSTRACT FROM AUTHOR]

Surface charge of biomaterials is one of the most influential parameters on regulating the complex processes of cell responses in tissue engineering. This study explores the contributions of xTa (x ? 5; 10; 30 in wt%) interface with the Ti as matrix on the in-vitro cell growth when such composites were produced through cold spray additive manufacturing. Preliminary results reveal that formation of intimate contact between deposited Ti and Ta splats provides meaningful differences in work function, results in an estimated surface potential variation around 50 mV, that ultimately influence cell growth. Increasing mass fraction of Ta in the chosen cold sprayed Ti-xTa composites was beneficial to initial cell attachment and proliferation upon the surface. Electrochemical response of cold sprayed coatings indirectly proves that Ta may act as anode and Ti performs as cathode in the electrochemical cells with possible surface charge gradient that allow to design and adapt biomaterials surfaces to a specific application. Understanding the mechanism of cell growth upon the surface of cold sprayed Ti-xTa composites will contribute to design of biomaterial surface for promising osseointegrity in biomedical applications. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has rekindled interest in the molecular mechanisms involved in the early steps of infection of cells by viruses. Compared to SARS-CoV-1 which only caused a relatively small albeit deadly outbreak, SARS-CoV-2 has led to fulminant spread and a full-scale pandemic characterized by efficient virus transmission worldwide within a very short time. Moreover, the mutations the virus acquired over the many months of virus transmission, particularly those seen in the Omicron variant, have turned out to result in an even more transmissible virus. Here, we focus on the early events of virus infection of cells. We review evidence that the first decisive step in this process is the electrostatic interaction of the spike protein with heparan sulfate chains present on the surface of target cells: Patches of cationic amino acids located on the surface of the spike protein can interact intimately with the negatively charged heparan sulfate chains, which results in the binding of the virion to the cell surface. In a second step, the specific interaction of the receptor binding domain (RBD) within the spike with the angiotensin-converting enzyme 2 (ACE2) receptor leads to the uptake of bound virions into the cell. We show that these events can be expressed as a semi-quantitative model by calculating the surface potential of different spike proteins using the Adaptive Poison-Boltzmann-Solver (APBS). This software allows visualization of the positive surface potential caused by the cationic patches, which increased markedly from the original Wuhan strain of SARS-CoV-2 to the Omicron variant. The surface potential thus enhanced leads to a much stronger binding of the Omicron variant as compared to the original wild-type virus. At the same time, data taken from the literature demonstrate that the interaction of the RBD of the spike protein with the ACE2 receptor remains constant within the limits of error. Finally, we briefly digress to other viruses and show the usefulness of these electrostatic processes and calculations for cell-virus interactions more generally.

The emergence of facial masks as a critical health intervention to prevent the spread of airborne disease and protect from occupational nanomaterial exposure highlights the need for fundamental insights into the interaction of nanoparticles (f) in the range of −10 V to −800 V were measured by an electrostatic voltmeter and used for testing. Results show that the mask filtration efficiency is highly dependent on the mask surface potential as well as the charge on the challenge aerosol, ranging from 60% to 98%. Eliminating the surface charge results in a maximum 43% decrease in filtration efficiency, emphasizing the importance of electrostatic charge interactions during the particle capture process. Moreover, increased humidity can decrease the surface charge on filters, thereby decreasing the mask filtration efficiency. The knowledge gained from this study provides insight into the critical role of electrostatic attraction in nanoparticle capture mechanisms and benefits future occupational and environmental health studies.

Monodispersed polyethylene glycol diacrylate (PEGDA)/acrylic acid (AA) microgels with a tuneable negative charge and macroporous internal structure have been produced using a Lego-inspired droplet microfluidic device. The surface charge of microgels was controlled by changing the content of AA in the monomer mixture from zero (for noncharged PEGDA beads) to 4 wt%. The macroporosity of the polymer matrix was introduced by adding 20 wt% of 600-MW polyethylene glycol (PEG) as a porogen material into the monomer mixture. The porogen was successfully leached out with acetone after UV-crosslinking, which resulted in micron-sized cylindrical pores with crater-like morphology, uniformly arranged on the microgel surface. Negatively charged PEGDA/AA beads showed improved adsorption capacity towards positively charged organic dyes (methylene blue and rhodamine B) compared to neutral PEGDA beads and high repulsion of negatively charged dye molecules (methyl orange and congo red). Macroporous microgels showed better adsorption properties than nonporous beads, with a maximum adsorption capacity towards methylene blue of 45 mg/g for macroporous PEGDA/AA microgels at pH 8.6, as compared to 23 mg/g for nonporous PEGDA/AA microgels at the same pH. More than 98% of Cu(II) ions were removed from 50 ppm solution at pH 6.7 using 2.7 mg/mL of macroporous PEGDA/AA microgel. The adsorption of cationic species was significantly improved when pH was increased from 3 to 9 due to a higher degree of ionization of AA monomeric units in the polymer network. The synthesized copolymer beads can be used in drug delivery to achieve improved loading capacity of positively charged therapeutic agents and in tissue engineering, where a negative charge of scaffolds coupled with porous structure can help to achieve improved permeability of high-molecular-weight metabolites and nutrients, and anti-fouling activity against negatively charged species.

Abstract Triboelectric nanogenerator (TENG) uses charge transfer between two asymmetric charge affinity materials such as metal and dielectrics. Metal electrode acts as charge collector from dielectrics and acts as charge transfer path to an external load, which model deals with only a net charge of metal electrode concerning electrical output. In this work, we found that metal electrode in triboelectric generator has non-negligible surface charge polarization causing open-circuit voltage difference in the model TENG system. The output voltage depends on the initial preparation conditions of the TENG for I–V measurements, even for the same measured charge densities. The measured output voltage difference with the same charge density implies that electric charges of TENG are composed of movable charges that affect current and voltage output and the bounded fixed charges that only affect open-circuit voltage.

Introduction: Nanoparticle evaluation within the pulmonary airspace has increasingly important implications for human health, with growing interest from drug delivery, environmental, and toxicology fields. While there have been widespread investigations of nanoparticle physiochemical properties following many routes of administration, nanoparticle behavior at the air-liquid interface (ALI) is less well-characterized.Methods: In this work, we fabricate two formulations of poly(ethylene)-glycol diacrylate (PEGDA)-based model nanoparticles to establish an in vitro workflow allowing evaluation of nanoparticle charge effects at the ALI.Results and Discussion: Both cationic and anionic PEGDA formulations were synthesized with similar hydrodynamic diameters around ∼225 nm and low polydispersity, with expected surface charges corresponding with the respective functional co-monomer. We find that both formulations are readily nebulized from an aqueous suspension in a commercial Aeroneb® Lab Nebulizer, but the aqueous delivery solution served to slightly increase the overall hydrodynamic and geometric size of the cationic particle formulation. However, nanoparticle loading at 50 μg/ml of either formulation did not influence the resultant aerosol diameter from the nebulizer. To assess aerosol delivery in vitro, we designed a 3D printed adapter capable of ensuring aerosol delivery to transwell 24-well culture plates. Nanoparticle uptake by macrophages was compared between traditional cell culture techniques and that of air-liquid interface-cultured macrophages following aerosol delivery. Cell viability was unaffected by nanoparticle delivery using either method. However, only traditional cell culture methods demonstrated significant uptake that was dependent on the nanoparticle surface charge. Concurrently, air-liquid interface culture resulted in lower metabolic activity of macrophages than those in traditional cell culture, leading to lower overall nanoparticle uptake at air-liquid interface. Overall, this work demonstrates that base-material similarities between both particle formulations provide an expected consistency in aerosol delivery regardless of the nanoparticle surface charge and provides an important workflow that enables a holistic evaluation of aerosolizable nanoparticles.

The use of paper dry strength additives is one of the methods for producing packaging boards with a lower grammage while maintaining mechanical properties. In the present work, papers were formed using dissolving grade kraft fibres, kraft fibres and carboxymethylated cellulose (CMC) modified kraft fibres (C-kraft fibres), with either cationic starch (CS), anionic polyacrylamide (APAM) or anionic polyelectrolyte complexes (PECs). Fibres and sheets were characterized to evaluate how the saturation adsorption of the different strength additives influences the properties of the treated fibres and the final handsheets. The tensile index of papers made from C-kraft fibres was the highest due to the highest adsorption capacity of strength additives. Moreover, the strength additives increased the tensile index by 33–84 %, while z-directional tensile strength was increased dramatically by 46–139 %. Bending stiffness was improved by 2.6–25 %, and the combination of CS and APAM or PECs resulted in a significant improvement in bending stiffness compared to the addition of CS alone. Importantly, the strength improvement did not sacrifice the density significantly. In summary, the knowledge gained from the current study expands the understanding of strength additives and their relationship with fibres of different surface charge and the overall paper properties. [ABSTRACT FROM AUTHOR]

In this research, the influence and comparison of ultrasonic and microwaves on the wettability of carbonate rock have been investigated. Wettability is one of the most fundamental parameters of the oil reservoir, according to which the fluid movement in the porous medium can be examined. The aged thin sections were placed in a microwave oven and an ultrasonic bath and they were exposed to radiation for 2-10 minutes. Using the contact angle analysis, it was observed that the angle between the rock and oil drop of microwaved and ultrasonicated samples changed by 57 and 71 degrees, respectively. Contact angle and temperature changes started faster for the ultrasonicated samples. The surface charge of the rocks was determined by zeta potential analysis, and it was found that in both samples, in the first minutes of radiation, negatively charged colloids were liberated from the samples by absorbing the waves, which reduced the surface negative charges, and with the continued radiation, positively charged colloids were decreased due to the evaporation of light oil compounds. The reduction of zeta potential occurred faster for the ultrasonicated sample, but the rate of decrease was lower. By examining Fourier-transform infrared spectroscopy (FTIR) results, it was concluded that the heavy compounds on the surface of the samples were cracked and turned into lighter hydrocarbons, and the changes for both samples were almost equal. Also, the polar compounds, sulfur, and nitrogen in samples increased, decreased, and decreased respectively for both samples, and these changes were more for the ultrasonicated samples. [ABSTRACT FROM AUTHOR]

The influence of the parameters of the working elements of sensors and antenna receiving and transmitting devices protected by dielectric caps on the intensity of exposure to atmospheric electricity is experimentally investigated. It is shown that, on extended electrodes, an artificial lightning cell induces more powerful streamer flashes than on concentrated rod electrodes; for reverse discharges, an inverse pattern is observed, which may be related to the area of charge accumulation on the inner surface of the dielectric cap. A relationship has been established between the nature and intensity of the ATC effect on sensor and antenna models and the radius of a cylindrical electrode or the radius of the edge of a flat disk electrode. It is established that, with an increase in the surface area of the electrode that models the working elements of the sensor or antenna receiving and transmitting device, the contribution of bias currents in the recorded total current increases significantly. It is shown that the parameters of the current pulses generated on the protected elements depend on the size and shape of the working area of these elements and on the location and area of charge accumulation on the inner surface of the dielectric cap. [ABSTRACT FROM AUTHOR]

The main purpose of this study is to reveal the growth mechanism of ice lens in saturated clay. The deformation and fracturing of clay skeletons caused by ice crystal growth during the freezing process are gradually discussed, and a theoretical model for the whole process of ice lens growth considering the surface charge is proposed. Firstly, the electrical properties of clay surfaces and the pore structure characteristics of frozen clay are introduced, and the stress of pore walls during the growth of single pore ice crystals is calculated. Secondly, the values of parameters in the theoretical formula of separation pressure between adjacent clay particles are given when considering the linear elasticity of clay. Finally, the formation mechanism of the new lens is described, and the crack growth velocity equation is given. This paper shows that: there is a good consistency between the soil tensile strength of the macroscopic dimension and the intergranular separation pressure of the molecular dimension in judging the production conditions of the new lens; the formation of the new ice lens is the result of the destruction of the pore structure and the propagation of cracks caused by the growth of ice crystals, and more pore freezing can be caused only when the infiltration path of the ice crystals is formed in the pore structure. In order to verify the model, the ultimate compressive strength of soil calculated in this study was compared with the existing test results, and the rationality and correctness of the model are discussed. This study is of great significance to accurately understand the frost heave process. [ABSTRACT FROM AUTHOR]

The ability to control the mobility and function of droplets is fundamental to developing open surface microfluidics. Despite notable progress in the manipulation of droplets, the existing strategies are still limited in functionalizing droplets. Herein, the coupling of droplet motion and functionalization elicited by an invisible charge wall is reported. The charged superamphiphobic surface is overlapped with a conductor to induce free charge, creating the invisible charge wall at the overlapping boundary. The charge wall can trap droplets and polarize them into Janus charged state. It is found that the trapping degree and the charge distribution in the Janus charged droplet depend on the original surface charge on the superamphiphobic surface. The invisible charge wall can also be established at diverse boundary curvatures, allowing to design pathways for droplet manipulations. Furthermore, the enrichment of protein and nanomaterial in the manipulated Janus charged droplet is demonstrated. The strategy provides a potential microfluidic platform with orthogonal functionalities. [ABSTRACT FROM AUTHOR]

Current monitoring (CM) is an indirect experimental method for characterizing surface zeta potentials in confined channels. Although this method has been successfully used in microchannels, its validity in nanofluidic devices has remained elusive due to non-negligible effects from relatively thick electrical double layers and large surface conduction. In this work, we numerically investigated current monitoring and its accuracy in nanochannels filled with the monovalent binary salt solution under various conditions, including different ionic concentrations, ion diffusivities, surface charge densities, and channel heights. Our results show that the zeta potential measured by current monitoring deviates from the actual value as the electrical double layer becomes thick, reaching zero when the Debye length is more than 15% of the half channel height. However, for cases with a smaller Debye length, the magnitude of deviation can be precisely predicted by a simple expression, which is only related to the ratio of the Debye length to the nanochannel height and the average ion diffusivity even when the surface conduction is in the moderate range. Our observations can be explained by the deionization shock wave effect, and this new expression provides guidelines for accurately measuring zeta potentials in nanochannels using current monitoring, which would lead to better control of electrokinetic flows for various nanofluidic applications. [ABSTRACT FROM AUTHOR]

We report the effects of a particle surface charge during translocation through a thin micropore based on the simulation and experiments. The translocation of carboxylated and nonfunctionalized polystyrene beads through a fabricated micropore was measured. To compare the translocation behaviors of a particle with/without surface charge under the same driving force, we used a pressure-driven method low bias voltage. We then analyzed the signals with two factors: the translocation time and blocking current. Based on the analysis, we found that, at a low flow rate, the translocation time was largely dependent on the surface charge of the particles. More importantly, we found an unusual phenomenon that the flow rate can affect the blocking current, and the level of effect was significantly determined by the particle's surface charge. To understand this phenomenon, we suggest a plausible mechanism considering the effect of the convective flow on the counterion flux and FEM results. [ABSTRACT FROM AUTHOR]

As interest in the extensive application of bulk nanobubbles increases, it is becoming progressively important to understand the key factors affecting their anomalous stability. The scientific intrigue over nanobubbles originates from the discrepancy between the Epstein–Plesset prediction and experimental observations. Herein, the coupling effects of ionic surfactants and electrolytes on the stability of bulk nanobubbles is studied. Experimental results show that ionic surfactants not only reduce the surface tension but also promote the accumulation of net charges, which facilitate the nucleation and stabilization of bulk nanobubbles. The addition of an electrolyte in a surfactant solution further results in a decrease in the zeta potential and the number concentration of nanobubbles due to the ion shielding effect, essentially colloidal stability. An adsorption model for the coexistence of ionic surfactants and electrolytes in solution, that specifically considers the effect of the adsorption layer thickness within the framework of the modified Poisson–Boltzmann equation, is developed. A quantitative agreement between the predicted and experimental surface tension is found in a wide range of bulk concentrations. The spatial distribution of the surface potential, surfactant ions and counterions in the vicinity of the interface of bulk nanobubbles are described. Our study intrinsically paves a route to investigate the stability of bulk nanobubbles. [ABSTRACT FROM AUTHOR]

Green and efficient acid protease has received increasing attention in bating wet blue (chrome tanned leather). However, acid proteases penetrate slowly in the wet blue, which reduces the dispersion efficiency and uniformity of hide collagen fibers. We explored the factors that affect the penetration of acid proteases in wet blue and the bating performance, including surface charge, molecular weight, particle size, and proteolytic activity of protease. The results show that the most important factor is the surface charge of the acid protease. The acid protease AP-2 derived from Trichoderma reesei had isoelectric point (pI) of 3.6 and penetrated the wet blue more deeply, thereby dispersing collagen fibers and softening the wet blue better than the pepsin (pI 1.9) and the acid protease AP-1 derived from Aspergillus usamii (pI 2.4). This finding is because the negatively charged pepsin and AP-1 are combined easily with the positively charged wet blue at the bating pH of 3.5 and stay on the surface layer rather than transfer into the inner layer of the wet blue. Therefore, choosing acid protease with the pI higher than the bating pH is important for deep penetration and good bating performance. [Display omitted] • Acid proteases had different isoelectric points (pIs) from 1 to 4. • Acid proteases had thermal stability and Cr3+ adaptability for bating environment. • Protease with pI higher than bating pH 3.5 penetrated rapidly in chrome tanned leather. • Positively charged protease penetrated rapidly and dispersed collagen fibers well. • Electrostatic interaction greatly affects protease penetration and bating performance. [ABSTRACT FROM AUTHOR]

The insulator in direct current gas-insulated transmission lines (DC-GIL) would suffer discharge risk due to surface charge accumulation under thermal-electric coupled fields. In this paper, the transient surface charge accumulation characteristics of a basin-type DC-GIL insulator is investigated via finite element method based on a three-dimension horizontally installed GIL model. The stationary temperature distribution of the model is obtained and then applied to the transient simulation of charge. Weak form partial differential equation is employed to deal with the ion transportation equation. Equations and parameters in the simulation are optimized to reduce the computing memory and time. Results indicate that the charge accumulation is accelerated due to the promotion of conduction through the insulator under thermal gradient. Higher charge density is obtained under thermal gradient. And the surface charge density of the convex surface is higher due to the promoted conduction. The highest field strength increases and the corresponding location moves along the convex surface during the transient process. This could attribute to the influence of transient charge behavior under thermal gradient on the electric field distribution. This study indicates that the thermal gradient and transient charge accumulation should be considered when dealing with the insulation characteristics of DC-GIL with insulators.

Microplastics (MPs) are perpetual contaminants that are mostly generated by human activity and are deposited in aquatic ecosystem. MPs may react differently in aquatic organisms depending on their size, surface charge, and concentration. The current investigation examined the interactions of polystyrene (PS) microplastics (of varied charges and sizes) with Scenedesmus obliquus, a unicellular phytoplankton. It is observed that 1 µm PS-MPs produced increased oxidative stress than 12 µm PS-MPs as indicated by total reactive oxygen species (ROS), superoxide and hydroxyl radical generation, and lipid peroxidation results. Additionally, decreased photosynthetic effectiveness, membrane integrity and esterase activity were also observed for the lower sized MPs. Antioxidant enzyme activities like superoxide dismutase (SOD) activity and catalase (CAT) activity correlated well with the oxidative stress generation in the cells. The effects by both the sizes of MPs were dose dependent in nature. Given the importance of a rapidly developing scientific literature on the effects of MPs in freshwater organisms, understanding the dynamics of interactions with lower-level organisms becomes very relevant.

Abstract Surface charge of biological and medical nanocarriers has been demonstrated to play an important role in cellular uptake. Owing to the unique physicochemical properties, charge-reversal delivery strategy has rapidly developed as a promising approach for drug delivery application, especially for cancer treatment. Charge-reversal nanocarriers are neutral/negatively charged at physiological conditions while could be triggered to positively charged by specific stimuli (i.e., pH, redox, ROS, enzyme, light or temperature) to achieve the prolonged blood circulation and enhanced tumor cellular uptake, thus to potentiate the antitumor effects of delivered therapeutic agents. In this review, we comprehensively summarized the recent advances of charge-reversal nanocarriers, including: (i) the effect of surface charge on cellular uptake; (ii) charge-conversion mechanisms responding to several specific stimuli; (iii) relation between the chemical structure and charge reversal activity; and (iv) polymeric materials that are commonly applied in the charge-reversal delivery systems. Graphical Abstract

• The coupling of the PCC membrane surface charge to the nanopore structure confers its high-power density. • PCC membranes have the advantages of simple preparation process and low cost. • PCC membrane shows a high-power density of 9 W/m2 at a 50-fold KCl gradient. • The connection 30 series of PCC devices can output voltages up to 2.24 V to directly power calculators and LEDs. Surface charge and nanoscale porous structure of ion-selective membranes have been considered prominent in affecting conversion capability of salinity gradient energy-to-power, while the synergistic contribution of them is conventionally overlooked, thus limiting their further development toward high-performance harvesting of salinity gradient energy. Herein, bioinspired by organisms achieving effective intracellular ion transport through their surface-charged nanochannels, we designed porous-charged cellulose membrane (PCC) by simultaneously engineering surface charge and pore structure, followed by desirably chemical and structural distinctions, such as high zeta potential and sulfonic acid group content of −44 mV and 1.22 mmol/g, large porosity of 84 % and pore volume of 0.01 cm3/g (d ≤ 10 nm), while just −23 mV, 42 %, 0.0036 cm3/g and 0 mmol/g for pristine cellulose. Such distinctions endow PCC with excellent ion transport rate and capability (high t + of 0.97 and η of 44.18 % in 0.001/0.01 M), correspondingly superhigh power density of 21.6 W/m2 (0.01/5 M), which surpasses that of most membrane materials, including biomass materials, synthesized polymers, and even some composite materials. By a tandem 30 PCC units, the output voltage of the designed PCC device reaches 2.24 V, which successfully powers calculator and light-emitting diode. In addition, our PCC demonstrates excellent stability in various pH system (from 3 to 11) during 30-day testing. The PCC with environmentally friendly, low cost, and large-scale advantages demonstrates strong competitiveness in advanced membrane materials toward high-performance manipulating ion transport. [ABSTRACT FROM AUTHOR]

[Display omitted] • SiO 2 @polymer nanoparticles with different surface charges are prepared for drilling fluid loss reduction. • Electrostatic forces between SiO 2 @polymer and bentonite play the decisive role in reducing fluid loss. • Electrostatic repulsion induces slow formation of thin and compact filter cake. • Electrostatic attraction induces fast formation of thick and loose filter cake. To elucidate the effects of filtration reducers' surface charge on drilling fluid filtration performance, three kinds of SiO 2 @polymer nanoparticles with different surface charges are prepared. When these nanoparticles are added into bentonite-based drilling fluids as filtration reducers, the negatively charged nanoparticles show the best filtration reduction performance while the positively charged nanoparticles show the most inferior filtration reduction performance. Moreover, more negative charges induce better filtration reduction performance. Conversely, more positive charges induce more inferior filtration reduction performance. The filtration performance of drilling fluids is decided by the compactness of the filter cake. And the interactions among the particles in the drilling fluids play an important role in affecting the compactness of filter cake. The electrostatic attraction forces between the positively charged nanoparticles and negatively charged bentonite particles promoted the aggregation before the formation of incompact filter cake, and the electrostatic repulsion forces between the negatively charged nanoparticles and negatively charged bentonite particles slowed down the aggregation of particles to form more compact filter cakes. These findings demonstrate the decisive role of surface charge of filtration reducers, which could provide guidance for searching suitable filtration controlling additives for drilling fluids in the future. [ABSTRACT FROM AUTHOR]

Per- and poly-fluoroalkyl substances (PFASs) are contaminants of emerging concern, yet the understanding of factors that control their leaching and release from contaminated soils remains limited. This study aimed to investigate the impact of dissolved organic carbon (DOC) on the release of PFASs—specifically, perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA)from soils contaminated by aqueous film forming foam (AFFF). Batch aqueous leaching experiments were conducted on AFFF-contaminated soils under alkaline solution conditions (pH 9.5, 10.5, and 12) as it enhances leaching of both PFAS and DOC. Leaching of PFOS was significantly increased under alkaline conditions. Although the leaching of PFAS generally increased with pH, PFOS appeared to be more retained under the very alkaline pH conditions used in this study. At the same solution pH, leaching of PFOS and DOC was less in Ca(OH) 2 than in NaOH. The retention of PFOS under these conditions may be attributable to the shielding of the negative charge of the soil components and colloids (e.g., DOC and clay minerals) in the leachates and/or the screening of negative charges on head groups of PFOS due to the high concentration of divalent cations. Solution chemistry affected desorption of PFOS more than PFHxS and PFOA. The study highlights that the influence of DOC on PFAS leaching and transport can be very complex, and depends on leachate chemistry (e.g., pH and cation type), PFAS chemistry, the magnitude of PFAS contamination and factors that influence the solid:liquid partitioning of organic carbon in soil. [Display omitted] • DOC affects PFAS leaching; impact varies with PFAS concentration & leachate chemistry. • Effect of DOC and solution chemistry on PFAS leaching is more pronounced for PFOS. • Increasing cation concentrations reduces PFAS mobility in environments at high pH. • Cations can decrease the leaching of PFAS at high pH via charge screening. • DOC has a small effect on PFOS desorption from highly contaminated soils. [ABSTRACT FROM AUTHOR]

Electric double layers (EDL) are formed in aqueous solution of electrolytes near electrically charged wall. Such EDLs play a crucial role in many interfacial phenomena, among which a nanoscale boiling process was studied with molecular dynamics simulations. Evaporation and boiling were investigated with aqueous solution of sodium chloride (NaCl), a typical inorganic electrolyte, in contact with an artificially charged platinum substrate. The heating area temperature of the substrate was controlled in a range from 500 to 800 K. The results indicate that the surface charge and the formed EDL suppress the bubble nucleation due to strengthened interaction between liquid molecules and the substrate. It was also shown that water molecules in the EDL exhibit orientational ordering even at higher temperatures. [Display omitted] • Nanoscale boiling was investigated in aqueous electrolyte solution on artificially charged substrate. • Surface charge generates on electric double layer (EDL) and suppresses nucleate boiling. • Surface charge effects are asymmetric between positive and negative surface charge. • Decayed length of EDL is much longer than that of the linearized Poisson–Boltzmann model with high concentration as solvent evaporated. • Water molecules in the adsorption layer have a weak orientational order. [ABSTRACT FROM AUTHOR]

Intracellular calcium ion detection is of great significance for understanding the cell metabolism and signaling pathways. Most of the current ionic sensors either face the size issue or sensitivity limit for the intracellular solution with high background ion concentrations. In this paper, we proposed a calmodulin (CaM) functionalized nanopore for sensitive and selective Ca2+ detection inside living cells. A salt gradient was created when the nanopore sensor filled with a low concentration electrolyte was in contact with a high background concentration solution, which enhanced the surface charge-based detection sensitivity. The nanopore sensor showed a 10 × sensitivity enhancement by application of a 100-fold salt gradient, and a detection limit of sub nM. The sensor had a wide detection range from 1 nM to 1 mM, and allowed for quick calcium ion quantification in a few seconds. The sensor was demonstrated for intracellular Ca2+ detection in A549 cells in response to ionomycin. [Display omitted] • A CaM-functionalized nanopore was developed for intracellular detection of Ca2+ concentration. • Application of salt gradient to improve the sensitivity of the sensor for 10 times. • A low LOD (∼0.92 nM) was obtained, with a detection range of 1 nM to 1 mM. • Monitored intracellular Ca2+ concentration change induced by ionomycin. [ABSTRACT FROM AUTHOR]

Worldwide, a considerable amount of oily wastewater is generated, with oil droplets from 2 to 200 nm that are difficult to separate because of their size and colloidal stability. This study presents a novel approach for effectively separating microemulsions via cubic silicon carbide (3C-SiC)-coated alumina (Al 2 O 3) membranes fabricated based on low pressure chemical vapor deposition (LPCVD). SiC was deposited at a relatively low temperature at 860 °C on 100 nm Al 2 O 3 membranes using two precursors: SiH 2 Cl 2 and C 2 H 2. With the increase in deposition time, up to 25 min, the pore size decreased from 41 nm to 33 nm, which is a smaller pore size of a SiC membrane than previously used for oil/water separation. The polycrystalline 3C-SiC-coated membranes showed improved hydrophilicity (water contact angle of 15°) and highly negatively charged surfaces (−65 mV). Microemulsion filtration experiments were carried out at a constant permeate flux (80 Lm−2 h−1) for six cycles with varying deposition time, pH, surfactant types, and pore sizes. The fouling of the SiC-coated membrane was, compared to the Al 2 O 3 membrane, effectively mitigated due to the enhanced electrostatic repulsion and hydrophilicity. Surfactant adsorption mainly occurred when the surface charge of the microemulsion and the membranes were opposite. Therefore, the surface charge of the alumina membrane changed from positive to negative when soaked in negatively charged microemulsions, whereas SiC-coated membranes remained negatively charged regardless of surfactant type. The membrane fouling was alleviated when the membrane and oil droplets had the same charge. Lastly, the 62 nm SiC-coated membrane with 20 min coating time was the best choice for the filtration of the microemulsion, because of the high rejection of the oil droplets and low fouling tendency. [Display omitted] • Ultrathin (18 nm) polycrystalline 3C-SiC was deposited onto a Al 2 O 3 membrane. • SiC membrane with the smallest pore size (33 nm) for oil/water separation. • Highly hydrophilic membranes with a negative surface charge were produced. • Various pore sizes of 3C-SiC coated membranes were compared. • A combination of high oil rejection and low (ir)reversible fouling was achieved. [ABSTRACT FROM AUTHOR]

The combustion of coal worldwide creates a large quantity of fly ash (FA), and the application of FA to agricultural soils is being encouraged as a resource utilization strategy. While most of our attention has focused on positive aspects such as nutrient supplementation and pollution mitigation, the negative impacts of FA have likely been overlooked. In this study, we examined the colloidal properties of FA and soil clay, aiming to demonstrate the ability of FA to increase the dispersibility and transportability of soil clay. Dynamic light scattering technique was coupled with the test tube method to track the kinetics and pH-dependent changes in the zeta potential, hydrodynamic size and colloidal stability of FA, soil clay and their mixtures. We found that FA occurred in solution as "negatively charged balls", and its negative surface charges increased with increasing pH. FA itself showed a low dispersibility; however, FA became more dispersive when it was introduced to clay suspensions. The mechanism is that the introduction of FA supplied more negative charges to the clay suspension, inducing electrostatic repulsion with soil clay, from which both FA and soil clay were favoured to disperse. Therefore, it can be inferred that off-site transport of FA is possible. More importantly, excessive application of FA can inadvertently intensify clay dispersibility, eventually resulting in soil clays together with FA being more vulnerable to leaching and/or surface run-off erosion. This suggests that the application of FA needs more careful consideration, and the development of more suitable techniques for the sustainable application of FA is still needed. [Display omitted] • Fly ash (FA) was found to carry negative charges over the pH range from ∼3 to ∼9. • Application of FA for soils can increase soil negative net charges. • Both FA and soil clay were favored to aggregate but their mixtures were dispersive. • Off-site cotransport of FA and soil clay needs to be considered. [ABSTRACT FROM AUTHOR]

Pickering emulsions stabilized by cellulose nanofibrils (CN) have sparked significant attention, however the fundamental mechanisms underpinning the stabilization process remain insufficiently elucidated. Focusing on an academic debate of surface charge's contribution to stabilization, this study first explored how the varying carboxyl group contents of TEMPO-oxidized CN (TCNs) impacted Pickering emulsions' formation and stability. TCNs with 662 μmol/g carboxyl groups exhibited distinctive attributes, including larger particle sizes (322 nm in length), improved thermal stability (maximum decomposition temperature of 317 °C), and increased viscosity (1.57 Paִִ⋅s) compared to their counterparts with 963–1011 μmol/g charge density. Notably, the former one, with a larger three-phase contact angle (51.5°), higher interfacial tension, and greater detachment energy (21.69 × 10−18 J), resulted in a homogeneous dispersion of spherical oil droplets and super-stable Pickering emulsions with a consistent emulsifying index of 100% over 30 days. These findings clearly clarified that TCNs with a lower charge density exhibit superior emulsifying properties. In addition, for the first time, a distinct oil droplet-decorated fibrillar structure was observed, probably suggesting that TCNs might be able to serve as anchoring matrixes to guide the distribution of oil droplets. These structures seemed to impeded the migration and accumulation of the oil droplets, consequently enhancing the stability of the resulting Pickering emulsions. To sum, this study clearly elucidated the role of surface charge in stabilizing cellulose-based Pickering emulsions and proposed a new model to expound the cellulose-oil interaction mechanisms, thus providing new theoretical and practical insights on utilization of CN as highly effective emulsifier for super-stable food-grade Pickering emulsions. [Display omitted] • TEMPO-oxidized nanofibrils (TCNs) are effective to stabilize Pickering emulsions. • Clarify surface charge's contribution and further understand stabilization mechanism. • Relatively low charge density instead of high charge density for better stability. • Distinct oil droplet-decorated fibrillar structures enhance emulsion's stability. [ABSTRACT FROM AUTHOR]

Mechanical properties of polymer modified mortar (PMM) were investigated using self-synthesized polymer latexes with varied glass transition temperature (T g) and colloidal surface charges to build correlations between the mechanical properties of PMMs and the intrinsic properties of the polymers. Generally, compressive strength and elastic modulus of mortar are decreased, but ductility and toughness are enhanced by incorporation of the polymers. Impacts of the lower T g polymers on the mechanical properties of PMMs are more pronounced. With increasing polymer content, flexural and tensile strength of mortar first increase and then decrease when using low T g polymers that form continuous film during hardening of the mortars, while steadily decrease in the case of high T g polymers that exist as individual particles in the hardened PMMs. For the high T g polymer modified mortars, it is interestingly found that a subsequential heat treatment effectively promotes the film formation of the polymers in the hardened PMMs and thus greatly increases their flexural and tensile strength. This indicates that polymer film formation is essential to the enhancement of the PMMs, because the polymer films play a crack-bridging effect while the individual particles cannot do such job. The high T g polymers lead to higher tensile strength of PMMs after heat treatment due to the higher inherent strength of the polymer film. Higher colloidal surface charge benefits the mechanical properties of the PMMs by (1) promoting a more homogenous polymer distribution in the hardened PMMs and/or (2) improving the bonding between the polymer phase and cement hydrates. [ABSTRACT FROM AUTHOR]

Plasmonic composites combining titanium dioxide (TiO 2) with highly dispersed noble metal nanoparticles have attracted great interest as they exhibit improved photocatalytic performance compared to the bare TiO 2. In this article, TiO 2 –Au composite nanorods were synthesised by wet impregnation in combination with calcination. The obtained plasmonic composites were characterized by TEM, SEM, XRD, N 2 sorption, UV-Vis diffuse reflectance spectroscopy (UV-Vis DR) and reversed double-beam photoacoustic spectroscopy (RDB-PAS) analysis. The RDB-PAS analysis revealed that the TiO 2 nanorods (TNR) contain amorphous areas on the surface that influence the size of the grown gold nanoparticles. The amount of amorphous phase on the TiO 2 surface of the analysed TNR samples increases from 16.4 %, 17 % and 20.2 % for TNR-A, TNR-B and TNR-C, respectively, and is closely related to the point of charge(pH PZC), which increases from the 3.9 ± 0.06, 4.7 ± 0.07 and 5.7 ± 0.04 for TNR-A, TNR-B and TNR-C, respectively. Au nanoparticle size distribution analysis obtained on the TNR surface shows that smaller Au nanoparticles are formed with pH PZC increase of the TNR support, i.e. 14.8 nm, 12.5 nm and 11.6 nm for TNR-A, TNR-B and TNR-C, respectively. This confirms that the differences in the surface charge of the TiO 2 support influence the extent of hydrolysis of the Au precursor and its subsequent nucleation. Finally, the formation of OH• radicals was monitored using fluorescence probe method with coumarin as the probe molecule. The results revealed that the TiO 2 /Au composites are capable of generating OH• radicals under visible light illumination, with cat-C, containing the smallest Au particle sizes, being the most active among the materials tested. [Display omitted] • Plasmonic Au/TiO 2 photocatalysts for visible light water treatment were designed. • TiO 2 nanorods supports with different surface charges were investigated. • Surface charge affects the amount of generated TiO 2 amorphouse phase on the support. • Amount of TiO 2 amorphous phase on the support affects the size of Au nanoparticles. • Size of Au nanoparticles depends on the surface charge of TiO 2 support. [ABSTRACT FROM AUTHOR]

Increased life expectancy in industrialized countries is causing an increased incidence of osteoporosis and the need for bioactive bone implants. The integration of implants can be improved physically, but mainly by chemical modifications of the material surface. It was recognized that amino-group-containing coatings improved cell attachment and intracellular signaling. The aim of this study was to determine the role of the amino group density in this positive cell behavior by developing controlled amino-rich nanolayers. This work used covalent grafting of polymer-based nanocoatings with different amino group densities. Titanium coated with the positively-charged trimethoxysilylpropyl modified poly(ethyleneimine) (Ti-TMS-PEI), which mostly improved cell area after 30 min, possessed the highest amino group density with an N/C of 32%. Interestingly, changes in adhesion-related genes on Ti-TMS-PEI could be seen after 4 h. The mRNA microarray data showed a premature transition of the MG-63 cells into the beginning differentiation phase after 24 h indicating Ti-TMS-PEI as a supportive factor for osseointegration. This amino-rich nanolayer also induced higher bovine serum albumin protein adsorption and caused the cells to migrate slower on the surface after a more extended period of cell settlement as an indication of a better surface anchorage. In conclusion, the cell spreading on amine-based nanocoatings correlated well with the amino group density (N/C).

Iron(III) oxides and oxyhydroxides are among the most reactive minerals in the environment, with surfaces that become charged when immersed in water. The governing role of surface charge over interfacial processes such as metal sorption is well understood. However, its role in interfacial redox reactions, such as when metal sorption is coupled to interfacial electron transfer (ET), is not. This is mainly because surface charge affects not only the types and densities of surface complexes formed but also their respective driving forces for ET. An important case is Fe(II)-catalyzed recrystallization of Fe(III)-oxyhydroxides, in which Fe(II) sorption and interfacial ET are closely linked. In this study, we used replica-exchange constant-pH molecular dynamics simulations (Zarzycki, P.; Smith, D. M.; Rosso, K. M. J. Chem. Theory Comput. 2015, 11, 1715-1724) to calculate the distance-dependent electrostatic potential at charged (110) surfaces of goethite particles, assessing its effect on previously computed Fe(II) sorption and interfacial ET free energies (Zarzycki, P.; Kerisit, S.; Rosso, K. M. J. Phys. Chem. C 2015, 119, 3111-3123). We show that Fe(II) adsorbs preferentially as an inner-sphere complex on the negatively charged surface, and as an outer-sphere complex on the positively charged surface because of both electrostatic repulsion and high energy barriers that arise from ordered water layers at the interface. The separation distance between adsorbed Fe(II) and the surface largely dictates adiabatic versus nonadiabatic ET regimes for this interface. The findings help unravel the pH dependence of Fe(II)-catalyzed recrystallization of goethite.

Nanomedicine has revolutionized disease theranostics by the accurate diagnosis and efficient therapy. Here, the PAMAM dendrimer decorated PVCL-GMA nanogels (NGs) were developed for favorable biodistribution in vivo and enhanced antitumor efficacy of ovarian carcinoma. By an ingenious design, the NGs with a unique structure that GMA-rich domains were localized on the surface were synthesized via precipitation polymerization. After G2 dendrimer decoration, the overall charge is changed from neutral to positive, and the NGs-G2 display the whole charge nature of positively charged corona and neutral core. Importantly, the unique architecture and charge conversion of NGs-G2 have a profound impact on the biodistribution and drug delivery in vivo. As a consequence of this alteration, the NGs-G2 as nanocarriers emerge the highly sought biodistribution of reduced liver accumulation, enhanced tumor uptake, and promoted drug release, resulting in the significantly augmented antitumor efficacy with low side effects. Remarkably, this finding is contrary to some reported work that the nanocarriers with positive charge have preferential liver uptake. Moreover, the NGs-G2 also displayed thermal/pH dual-responsive behaviors, excellent biocompatibility, improved cellular uptake, and stimuli-responsive drug release. Encouragingly, this work demonstrates a novel insight into the strategy for optimizing design, improving biodistribution and enhancing theranostic efficacy of nanocarriers.