Electrostatic Phenomena Research Articles

Emulsifiers from mealworm

Aqueous extracts obtained from the larvae of Tenebrio molitor (“mealworms”) have been used as sole emulsifiers for oil–in–water emulsions. For an oil volume fraction of 0.2, they produced coalescence-stable droplets of a few μm at a minimal concentration of 1 g dL−1 and flocculated systems at higher concentrations. Size exclusion chromatography showed that the extracts consist of a polysaccharidic and a proteinic macromolecular population, and of smaller molecules; SDS-displacement experiments showed that proteins are found to be the main component that adsorbs and stabilizes the oil–in–water interfaces. This is verified by interfacial measurement experiments. Removal of the smaller molecules produced efficient emulsifiers without flocculation, suggesting that the latter is due to electrostatic phenomena, rather than depletion. The zeta potential of this purified extract was very sensitive to pH changes between 6 and 7, allowing for specialized/pH-sensitive uses. The results suggest that mealworm extracts show potential as emulsifiers without the need of further purification (e.g. protein isolation), and can lead to high added-value products, while avoiding the consumers’ subconscious connection of these ingredients to their original sources.

Improvement and compensation of temperature drift of scale factor of a SOI-based MEMS differential capacitive accelerometer

In recent years, the analysis and improvement of temperature characteristics of Si-based capacitive accelerometers has received considerable research attention in the field of Microelectromechanical system (MEMS) sensors. Generally, the influence of temperature on the accelerometers can be mitigated by optimizing the structural design and compensating the output signal. Herein, the output characteristics of an accelerometer designed with asymmetrically arranged combs were analyzed under various temperatures. The purpose of this paper is to improve the temperature drift of scale factor (TDSF) of MEMS capacitive accelerometer, using the asymmetric layout structure to improve the TDSF fundamentally, and the least square method to achieve temperature compensation efficiently. The variations in the TDSF were compared for the symmetric and asymmetric structures. In addition, we modeled the accelerometer with an asymmetric structure for simulations to analyze the errors resulting from the electrostatic torsion phenomenon induced by the asymmetric structure. Moreover, a temperature compensation model was developed for the scale factor of the accelerometer, which was validated and verified with the data obtained from simulations and experiment. Furthermore, an accelerometer based on silicon on insulator was fabricated and tested to verify the simulation results and the compensation effects. According to the results, the scale factor of the studied accelerometer was 171.83 mV g−1 and the average value of the TDSF was 83.56 ppm °C−1 Overall, the experimental results were almost consistent with the simulation results. Under the asymmetric layout, the scale-factor stability improvement of the accelerometer could reach up to 86.96%, and the error caused by electrostatic torsion was ∼2.93%, which is relatively negligible. After compensation, the range and standard deviation of the scale factor of the accelerometer with respect to temperature were reduced by 94.46% and 95.69%, respectively, and the average value of TDSF was reduced by 95.90%, which verified the effectiveness of the compensation model.

Anionic Phospholipids Shift the Conformational Equilibrium of the Selectivity Filter in the KcsA Channel to the Conductive Conformation: Predicted Consequences on Inactivation.

Here, we report an allosteric effect of an anionic phospholipid on a model K+ channel, KcsA. The anionic lipid in mixed detergent-lipid micelles specifically induces a change in the conformational equilibrium of the channel selectivity filter (SF) only when the channel inner gate is in the open state. Such change consists of increasing the affinity of the channel for K+, stabilizing a conductive-like form by maintaining a high ion occupancy in the SF. The process is highly specific in several aspects: First, lipid modifies the binding of K+, but not that of Na+, which remains unperturbed, ruling out a merely electrostatic phenomenon of cation attraction. Second, no lipid effects are observed when a zwitterionic lipid, instead of an anionic one, is present in the micelles. Lastly, the effects of the anionic lipid are only observed at pH 4.0, when the inner gate of KcsA is open. Moreover, the effect of the anionic lipid on K+ binding to the open channel closely emulates the K+ binding behaviour of the non-inactivating E71A and R64A mutant proteins. This suggests that the observed increase in K+ affinity caused by the bound anionic lipid should result in protecting the channel against inactivation.

Exploiting kaolinite-alumina heteroaggregation in Pickering emulsion stabilisation and porous mullite fabrication

Clay particles have gained considerable attention as a potential option for stabilising Pickering emulsions in recent years, which are promising templates for the development of porous ceramics intended for high temperature applications. However, the development of porous ceramics using this approach requires control over a number of factors such as stability, microstructure, rheology, and processability of the Pickering emulsions. In this work, we discuss a versatile approach for formulating porous mullite ceramics from emulsions stabilised by oppositely charged kaolinite and alumina particles. In this process, we exploit the electrostatic heteroaggregation phenomena in the oppositely charged mixed colloidal particle system. The aggregates formed by electrostatic interaction readily adsorb to the interface created during emulsification and favor the formation of highly stable Pickering emulsions. The influence of parameters such as concentration of each particle in the mixture, pH, and total particle concentration on the microstructure of Pickering emulsions are studied. We further show that processable Pickering emulsions can be engineered by in-situ surface modification of the hetero-aggregates using a short-chain amphiphile. Porous mullite ceramic is obtained by drying and sintering the optimised emulsion formulation. The phase evolution, microstructure, and porosity of the resulting ceramic are characterised. The macroporous mullite developed through this approach can be used as thermal insulator due to low thermal conductivity and tailored microstructure.

Energy collection generator based on electrostatic conversion mechanism

It is commonly acknowledged that, the electrostatic discharge phenomenon induced by charge transfer is accompanied by a huge loss of energy. That is why the collection and utilization of electrostatic energy are expected to alleviate the problem of the global energy supply shortage to a great extent. However, the electrostatic pulse will release hundreds of millions of joules of energy in a short time, which makes the conversion of electrostatic energy a big challenge. This paper proposes an effective electrostatic conversion mechanism to provide a potential reference solution for such a problem. Based on the above-mentioned principles, a novel electrostatic conversion device (ECD) is realized through the 180nm bipolar complementary-metal-oxide-semiconductor double-diffused-metal-oxide-semiconductor (BCD) process. ECD can convert discrete electrostatic pulses into stable current output in a short time interval (20ns∼100ns). The electrostatic voltage will also be clamped to a low level, effectively avoiding the risk of electrostatic breakdown. The experiment results show that the amplitude of the steady output electrostatic current increases with the increase in the electrostatic pulse voltage. ECD meets the application requirements of large-scale on-chip integration, and can be used as a prototype device for energy collection generators to further promote the development of electrostatic energy collection technology.

Theoretical and experimental analyses of the dynamic electroadhesion force

Electroadhesion (EA) is a polarization-induced dynamic electrostatic attraction phenomenon, including the saturation and attenuation delays of the EA force, and its repeatability under repeated application. Due to the complex polarization and dielectric relaxation mechanisms, it is pretty challenging to establish a theoretical EA model to clearly reveal the underlying polarization behind the dynamic EA force. In this paper, a theoretical model is proposed to describe the dynamic EA effect and analyze the dynamic EA characteristics by establishing the relationship between the EA force and polarization and introducing the Debye model into the polarization function. This model suggests that interfacial polarization is responsible for the dynamic behavior of EA force, which results in the saturation and attenuation delays, as well as the poor repeatability of EA force. Theoretical analysis also indicates that the application of an AC voltage can reduce the saturation and attenuation delays and enhance force repeatability by alleviating this effect, and that increasing the voltage frequency will reduce the EA force and eventually stabilize the EA force at hundreds of Hertz. Experiments show that our theoretical model can well explain the saturation and attenuation delay time scales, as well as the dependence of EA force on charging/discharging cycle and frequency. This work not only provides a theoretical tool for analyzing the dynamic EA effect but also offers potential strategies to improve EA performance.

Research on Self-Powered Coded Angle Sensor for Rock Climbing Training

Rock climbing speed is an important indicator for coaches to evaluate athletes, so it is necessary to be monitored in real-time. Rock climbing speed is currently measured by an angle sensor, but an angle sensor with self-powered function will be more suitable for actual working conditions. Triboelectric nanogenerators originate from triboelectric and electrostatic induction phenomena, and if sensors are developed based on the triboelectric nanogenerators, they will have self-powered function. In this research, a self-powered coded angle sensor which can measure the rotation angle, rotation direction, and rotation speed is proposed based on a single-electrode triboelectric nanogenerator. The power generation test results show that the maximum output power is about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9.5\times 10$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−7</sup> W with a load resistance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{6} \Omega $ </tex-math></inline-formula> . The sensing test results show that the resolution of angle measurement is 22.5°, the measurement range of rotation speed is 0–900 r/min, the measurement error is less than 5%, and the working temperature and humidity range are 0 °C–160 °C and 0%–90%, respectively. Compared with the conventional rock climbing sensor, the sensor has the function of self-powered function. It can effectively avoid the potential safety hazard caused by the power cable of the traditional indoor rock climbing sensor entangled with athletes and can also extend the application range of the sensor to the wild climbing environment without a power supply.

Highly efficient Cu-doped BTC aerogel for lead ions adsorption from aqueous solution: statistical modeling and optimization study using response surface methodology

• Aerogel adsorbent were prepared with the incorporation of Cu-BTC and characterized. • The CCD-RSM design was used to optimize the removal of Pb(II) from an aqueous solution . • The adsorbent concentration, time, and pH were studied and optimized. • Aerogel adsorbent were found to have a high adsorption efficiency for the removal Pb(II) ions. • Adsorption mechanism proposed chemical bonding and electrostatic interaction phenomena. In this study, a new kind of Cu-doped BTC (Cu-BTC/CH) aerogel adsorbent is synthesized for the removal of Pb(II) ions from aqueous solutions. A Cu-BTC/CH aerogel was made by covalent crosslinking with a hierarchical structure. The prepared aerogel adsorbent material was characterized by scanning electron microscope (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). The response surface methodology (RSM) was used to optimize the independent variables such as adsorbent concentration (0.2-1.2 g/L), time (20-180 min), and pH (3-7) respectively. The statistical techniques analysis of variance (ANOVA) indicated that the experimental results and the quadratic model were in good agreement (R 2 = 0.9882). The RSM model predicted that pH 6.5, adsorbent concentration of 1.15 g L −1 , and contact time of 170 minutes were the best experimental conditions for 99.96 % removal of Pb(II) ions. The highest Langmuir adsorption capacity for Pb(II) ions was found to be 204.08 mg g −1 with the correlation coefficient (R 2 = 0.99). The adsorption of Pb(II) ions on the aerogel adsorbent is an exothermic and spontaneous process with the negative ΔG°. The prepared adsorbent can be reusable for up to five consecutive regeneration cycles with the negligible effect of interfering ions. The mechanism of adsorption of Pb(II) ions was explained by XRD and XPS study and the adsorption phenomenon might be due to –OH, –NH 2 , and –COO − groups respectively. Considering all this, the proposed method is an effective and adaptable way to transform a huge amount of metal-organic framework (MOF) particles into a solid form and expand their use in water treatment. Graphical abstract

ПРИЛАГАНЕ НА ПРОБЛЕМНО-ОРИЕНТИРАНИЯ ПОДХОД ПРИ ИЗУЧАВАНЕ НА ЕЛЕКТРОСТАТИЧНИ ЯВЛЕНИЯ В ДЕСЕТИ КЛАС

Electrostatic phenomena and related physical quantities and physics laws are abstract for students. They find it difficult to understand the physics nature of the phenomena of electrification of bodies, electrostatic induction, polarization of dielectrics, as well as the laws associated with them. Our leading idea is to teach the theoretical material in electrostatics on the basis of the use problem-oriented approach with a physics training experiment. We offer a methodology for use the problem-oriented approach in the study of electrostatic phenomena in tenth grade. The teaching methodology follows the scheme: 1. Updating students’ knowledge of electrification of bodies, electric field, conductors and dielectrics. 2. Setting practical experimental tasks of problematic nature to students. 3. Realization of a physics training experiment and observation and analysis of the changes in the behavior of the bodies used. Emphasis is placed on practical experimental tasks of a problematic nature. The main task is to construct an electroscope from the students with available materials and to propose and implement experiments to show electrostatic phenomena. The described experiments are a real opportunity to understand the physical nature of electrostatic phenomena. They are a valuable didactic tool for the formation of quality knowledge and experimental skills in students. They develop the scientific style of thinking and skills for predicting and explaining real physics processes and phenomena.

Swamp Wetlands in Degraded Permafrost Areas Release Large Amounts of Methane and May Promote Wildfires through Friction Electrification

Affected by global warming, permafrost degradation releases a large amount of methane gas, and this part of flammable methane may increase the frequency of wildfires. To study the influence mechanism of methane emission on wildfires in degraded permafrost regions, we selected the northwest section of Xiaoxing’an Mountains in China as the study area, and combined with remote sensing data, we conducted long-term monitoring of atmospheric electric field, temperature, methane concentration, and other observation parameters, and further carried out indoor gas–solid friction tests. The study shows that methane gas (the concentration of methane at the centralized leakage point is higher than 10,000 ppm) in the permafrost degradation area will release rapidly in spring, and friction with soil, surface plant residues, and water vapor will accelerate atmospheric convection and generate electrostatic and atmospheric electrodischarge phenomena on the surface. The electrostatic and atmospheric electrodischarge accumulated on the surface will further ignite the combustibles near the surface, such as methane gas and plant residues. Therefore, the gradual release of methane gas into the air promotes the feedback mechanism of lightning–wildfire–vegetation, and increases the risk of wildfire in degraded permafrost areas through frictional electrification (i.e., electrostatic and atmospheric electrodischarge).

Performance evaluation of an industrial ceramic nanofiltration unit for wastewater treatment in oil production

An industrial ceramic nanofiltration membrane (pore size 0.9 nm) was tested in a Canadian oil field for more than 12,500 h to treat wastewater directly from daily operations, without any type of pre-treatment. This wastewater contained a high content of total suspended solids (13 to 510 mg/kg), and total organic carbon (31 to 134 mg/kg). The membrane unit was operated at different transmembrane pressure (TMP) set points (4–16 bar) and recovery set points (40–80%). The data show that ion and compound rejection depend strongly on a combination of both TMP and recovery, with the largest rejection occurring at low recovery values and high TMP values. Two mechanisms were responsible for rejection: sieving, which mostly impacted compound rejection, and electrostatic phenomena that impacted ion rejection. It is shown that ion rejection depends linearly on charge density of the ion. Ion rejection was measured as high as 85% and compounds (such as TSS) were rejected as high as 100%. The specific flux varied between 1–10 L/(m2.h.bar). Results from this field testing indicate the possibility of using these types of ceramic membranes for oil field wastewater treatment.

Electrostatic Coupling in MoS2/CuInP2S6 Ferroelectric vdW Heterostructures

AbstractFerroelectric van der Waals (vdW) heterostructure have recently emerged as a low‐power, versatile device paradigm because it combines the great diversity of the 2D materials and the memory nature of ferroelectrics. The non‐volatile field effect generated by the polarization bound charge is the pivotal factor for the device's performance. Unfortunately, microscopic studies on the interplay between polarization switching and electrostatic coupling at the heterojunction remain largely overlooked. Herein, the authors investigate the electrostatic coupling phenomena of vdW heterostructures consisting of semiconducting MoS2 and ferroelectric CuInP2S6. Significant charge injection accompanying the polarization reversal appears to be the governing field effect that modulates the electronic and photoluminescent properties of MoS2, as revealed by correlated ferroelectric domain, surface potential, and photoluminescence microscopies. Conversely, the photoactivity of the MoS2 also affects the polarization stability of CuInP2S6. This work provides direct microscopic insight into the mutual electrostatic interactions in vdW ferroelectric‐semiconductor heterojunctions, which has broad implications for ferroelectric field‐effect applications.

Particle-Induced Electrostatic Repulsion within an Electric Curtain Operating below the Paschen Limit.

The electric curtain is a platform developed to lift and transport charged particles in air. Its premise is the manipulation of charged particles; however, fewer investigations isolate dielectric forces that are observed at lower voltages (i.e., less than the Paschen limit). This work focuses on observations of simultaneous dielectrophoretic and electrostatic forces. The electric curtain was a printed circuit board with interdigitated electrodes (0.020 inch width and spacing) coated with a layer of polypropylene, where a standing wave or travelling wave AC signal was applied (50 Hz) to produce an electric field below the Paschen limit. Soda lime glass beads (180–212 µm) demonstrated oscillatory rolling via dielectrophoretic forces. In addition, several particles simultaneously experienced rapid projectile repulsion, a behavior consistent with electrostatic phenomena. This second result is discussed as a particle-induced local increase in the electric field, with simulations demonstrating that a particle in close proximity to the curtain’s surface produces a local field enhancement of over 2.5 times. The significance of this is that individual particles themselves can trigger electrostatic repulsion in an otherwise dielectric system. These results could be used for advanced applications where particles themselves provided triggered responses, perhaps for selective sorting of micrometer particles in air.

Electrostatic charging phenomena on material web electro field meter measurements in a production machine and their interpretation

After many years of industrial experience and investigation of various fires in web-fed presses, it became clear that there is no generally valid explanation for the phenomenon of electrostatic charging of high-speed material webs (e.g., paper, film, composites). The first measurement results and their interpretation are presented for discussion. The measurements with an electro field meter have shown that after a rubber roller there are strong variations of the E-field at constant distance in a very short time which are shown i.e. in Fig. 8.Various studies on the interpretation of electrostatic charge phenomena on material webs, particularly regarding high separation speeds (currently up to more than 30 m/s), have shown that in the conventional manner, i.e., with the classical theory of Helmholtz double layers, not all electrostatic problems can be satisfactorily explained or predicted. From the potential hazards of high charged material webs, suggestions for the placement of ionizers are defined. This paper is intended as a stimulus for further research into the electrostatic processes at work in the processing of material web.

Accelerating the charge inversion algorithm with hierarchical matrices for gas insulated systems

Surface charges accumulating on dielectrics during long-time operation of Gas Insulated High Voltage Direct Current (HVDC-GIS) equipments may affect the stable operation and could possibly trigger surface flashovers. In industrial applications, to quantify and identify the location of the surface charge accumulation from experimental measurements, the surface potential distribution is evaluated using, e.g., electrostatic probes, then the charge density is determined by solving an electrostatic problem based on an inversion procedure known as Charge Inversion Algorithm. The major practical limitation of such procedure is the inversion and the storage of the fully dense matrix arising from the representation via Integral Equations of the electrostatic phenomenon, resulting in O(N 3) computational complexity and O(N 2) memory requirement. In this paper it is shown how hierarchical matrices can be efficiently used to accelerate the charge inversion algorithm and, more importantly, reduce the overall memory requirement.

Maximizing Information: A Machine Learning Approach for Analysis of Complex Nanoscale Electromechanical Behavior in Defect-Rich PZT Films.

Scanning Probe Microscopy (SPM) based techniques probe material properties over microscale regions with nanoscale resolution, ultimately resulting in investigation of mesoscale functionalities. Among SPM techniques, piezoresponse force microscopy (PFM) is a highly effective tool in exploring polarization switching in ferroelectric materials. However, its signal is also sensitive to sample-dependent electrostatic and chemo-electromechanical changes. Literature reports have often concentrated on the evaluation of the Off-field piezoresponse, compared to On-field piezoresponse, based on the latter's increased sensitivity to non-ferroelectric contributions. Using machine learning approaches incorporating both Off- and On-field piezoresponse response as well as Off-field resonance frequency to maximize information, switching piezoresponse in a defect-rich Pb(Zr,Ti)O3 thin film is investigated. As expected, one major contributor to the piezoresponse is mostly ferroelectric, coupled with electrostatic phenomena during On-field measurements. A second component is electrostatic in nature, while a third component is likely due to a superposition of multiple non-ferroelectric processes. The proposed approach will enable deeper understanding of switching phenomena in weakly ferroelectric samples and materials with large chemo-electromechanical response.

A Non-Aqueous Potassium-Ion Hybrid Supercapacitor for High Power Applications

With the increase of energy storage demand for many applications, sustainable technologies must be developed. On one hand, Li-ion batteries (LIBs) offer high energy density but high cost and safety issues for high-power density applications, especially at low temperature. On the other hand, supercapacitors (SCs) exhibit high power and cyclability but insufficient energy density and self-discharge problems. The aforementioned properties result in a performance gap between LIBs and SCs. They are unable to meet the requirements for specific applications for storing/delivering large amount of energy within a short time during many cycles like regenerative braking in vehicles, memory backup in electronics or high voltage pulse delivery in industrial and medical sectors. Therefore, devices with a good energy density, an excellent power density and a long cycling stability are urgently required. This is the purpose of a hybrid capacitor by combining the electrostatic phenomena at a positive capacitor-type electrode and the faradic process at an oversized negative battery-type electrode. Fast charging is then possible while ensuring a higher energy density than conventional EDLCs. This higher energy density is possible because of the widen operating voltage range in hybrid configuration. Thanks to the deployment of Li-ion battery, the use of lithium is generally applied on hybrid capacitors. However, technologies using lithium chemistries (LIC and LIB) are dependent on critical and strategic materials (copper, lithium), use carbonate electrolytes and give rise to safety problems and a limited lifetime linked to the formation of dendrites. The idea of replacing lithium with other alkali elements is then gradually emerging. For example, potassium benefits of abundant resources, low standard electrode potential as well as low costs.The potassium-ion capacitor (KIC) presented here consist of an activated carbon positive electrode and a graphite negative one immersed in an acetonitrile based-non-aqueous electrolyte and a potassium salt. The hybrid configuration avoids specific problems inherent in the use of potassium. Indeed, the system is designed so that a high stage of graphite intercalation compound (GIC) is obtained in order to avoid critical volume expansion. Furthermore, with the spontaneous reaction between acetonitrile and metallic alkali elements, dendrites formation is not possible.However, the technology still faces obstacles that are being studied to be removed. Among them, a non-monotonous cycle ageing, with discharged capacities which decrease then increase drastically in a few thousand cycles, as well as a non-reproducibility of the results for identical cells were observed with the system initially developed. These results will be presented in order to show how they could be improved. In addition, the operation of KIC systems results in gas generation that induces cell swelling. This is a well-known issue whether for supercapacitors or Li-ion batteries. In the case of KIC technology, it has been proven to result from the combination of SEI formation at the negative electrode and side reactions between the functional groups of the positive electrode and the electrolyte. All these results highlight the necessity to develop an adequate formation protocol for KIC cells. Indeed, the first cycles of use of an electrochemical system, known as "formation", are essential to ensure its proper long-term operation.In the case of Li-ion battery, the formation protocol is well defined with galvanostatic charge/discharge cycles at low current regime and high temperature. Whereas in the case of KICs, about ten cycles at 5C/5D (C the theoretical value of the positive electrode capacity) and at room temperature were performed. The influence of the current regime and the temperature during first galvanostatic charge/discharge cycles were investigated to define a protocol specific to KIC cells and will be presented. In addition, another type of formation was considered following the swelling tests, which will be presented in order to understand the approach followed. Three different formations principles (Figure) were therefore tested. The first leads to non-reproducible and unstable performance. The second conducts in reproducible results but unstable long-term performance. The last provides stable and reproducible results with high energy densities. The cells started then aging tests at 100C/100D, which corresponds to a charge/discharge time of 30 seconds. Those having undergone the last formation show an excellent stability in cycling over more than 100,000 cycles. The stability of the energy density of KIC during long-term cycling is highly remarkable and hardly observed in the case of LIC.To conclude, the potassium-ion capacitor presented offers a good energy density of up to 14 Wh/kgelectrochemical core at pouch cell level, the possibility of fast charging and a long stability cycling. Improvements are still needed for operation at different temperatures and self-discharge. Figure 1

Electromagnetic–Triboelectric Hybridized Nanogenerators

Since the triboelectric nanogenerator (TENG) was invented, it has received extensive attention from researchers. Among the many pieces of research based on TENG, the research of hybridized generators is progressing rapidly. In recent years, the research and application of the electromagnetic–triboelectric hybridized nanogenerator (EMG-TENG) have made great progress. This review mainly focuses on the latest research development of EMG-TENG and elaborates on the principles, materials, structure, and applications of EMG-TENG. In this paper, the microscopic charge transfer mechanism of TENG is explained by the most primitive friction electrification phenomenon and electrostatic induction phenomenon. The commonly used materials for fabricating TENG and the selection and modification methods of the materials are introduced. According to the difference in structure, EMG-TENG is divided into two categories: vibratory EMG-TENG and rotating EMG-TENG. The summary explains the application of EMG-TENG, including the energy supply and self-powered system of small electronic devices, EMG-TENG as a sensor, and EMG-TENG in wearable devices. Finally, based on summarizing previous studies, the author puts forward new views on the development direction of EMG-TENG.

Structure and Surface Complexation at the Calcite(104)-Water Interface.

Calcite is the most stable polymorph of calcium carbonate (CaCO3) under ambient conditions and is ubiquitous in natural systems. It plays a major role in controlling pH in environmental settings. Electrostatic phenomena at the calcite-water interface and the surface reactivity of calcite in general have important environmental implications. They may strongly impact nutrient and contaminant mobility in soils and other subsurface environments, they control oil recovery from limestone reservoirs, and they may impact the safety of nuclear waste disposal sites. Besides the environmental relevance, the topic is significant for industrial applications and cultural heritage preservation. In this study, the structure of the calcite(104)-water interface is investigated on the basis of a new extensive set of crystal truncation rod data. The results agree with recently reported structures and resolve previous ambiguities with respect to the coordination sphere of surface Ca ions. These structural features are introduced into an electrostatic three-plane surface complexation model, describing ion adsorption and charging at the calcite-water interface. Inner surface potential data for calcite, as measured with a calcite single-crystal electrode, are used as constraints for the model in addition to zeta potential data. Ion adsorption parameters are compared with molecular dynamics simulations. All model parameters, including protonation constants, ion-binding parameters, and Helmholtz capacitances, are within physically and chemically plausible ranges. A PhreeqC version of the model is presented, which we hope will foster application of the model in environmental studies.

활선 DC선로 절연상태 모니터링을 통한 스마트 그리드 시스템 성능유지

With the development of distributed power generation using solar power and renewable energy, smart grid-type DC power distribution is gradually spreading. However, DC distribution has a disadvantage in that the electric corrosion phenomenon of the ground electrode is prominent compared to the AC distribution system. The destruction of the stability of the ground electrode due to the electrostatic phenomenon deteriorates the reliability of the distribution system by causing electric shock accidents to human life, failure and malfunction of equipment. Therefore, the main issues of DC distribution are the electric corrosion of the ground electrode and the need to increase the reliability of the distribution system for smooth power supply. In this paper, the insulation resistance measurement device (IMD: Insulation Monitoring Device) is to be researched and developed to measure the insulation resistance in the live state and monitor the insulation state of the power line in order to secure the insulation resistance of the line and to secure electrical safety through monitoring. Based on this study, we intend to analyze the reliability of equipment safety according to IT (non-grounding) ground fault and power line insulation resistance degradation.