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In this current paper, we report the use of inexpensive, simple electrophoretic deposition (EPD) technique in developing polyaniline (PANI) aqueous colloidal suspension coating on copper (Cu) substrate. Polyaniline nanoparticle films were deposited electrophoretically on the surface of copper sheet electrode. A colloidal suspension with high stability was produced by a liquid polyaniline in the presence of formic acid and acetonitrile as electrolyte for the EPD process. The suspension of the PANI was characterized by measuring the zeta potential of the suspension using zeta-sizer analyser. The PANI coating was used as barrier for corrosion protection of the Cu sheet. Operating parameters such as operating time, applied voltage, and the concentration were used with deposition at the cathode. Characterization such as XRD, SEM, FT-IR, and UV–Vis was carried out, and the corrosion protection offered by the PANI on the Cu surface was examined using potentiodynamic (Tafel) polarization in 3.5% NaCl solution at room temperature. As a result, the optimum parameters for obtaining a homogenous coating on the Cu sheet were attained at the voltage of 15 V and deposition time of 180 s with 50 mg/mL PANI concentration. The attained results indicated inhibition efficiency for PANI deposit of 92.92% indicating protection against corrosion.

Microbial fuel cell (MFC) systems have been developed for potential use as power sources, along with several other applications, with bacteria as the prime factor enabling electrocatalytic activity. Limited voltage and current production from unit cells limit their practical applicability, so stacking multiple MFCs has been proposed as a way to increase power production. Special attention is paid to voltage reversal (VR), a common occurrence in stacked MFCs, and to identifying the mechanisms underlying this phenomenon. We also proposed realistic perspectives on stacked MFCs in an effort to control and suppress VR by balancing the kinetics in the system, such as using enriched electroactive microorganisms or altering the circuitry mode. MFCs have been proposed as alternative renewable power sources since their inception, but the scale of MFC voltage and current production is too limited to meet market needs.Although stacks appear to provide the most suitable method for improving MFC performance, a phenomenon called voltage reversal (VR) hinders their performance.Imbalances between unit-cell performances, especially due to the current production capacity, are thought to be the major cause of VR, and the maximum current can be used as an indicator of VR.VR may be controlled and prevented using various electrical circuit configurations and electronic methods, and by understanding how to control current balance, to increase the current production capacity in stacked MFCs.Practical methods for controlling VR in stacked MFCs are useful for scaling up MFCs with higher performance.

• Whereas the role of calcium ions (Ca2+) in plant signaling is well studied, the physiological significance of pH-changes remains largely undefined. • Here we developed CapHensor, an optimized dual-reporter for simultaneous Ca2+ and pH ratio-imaging and studied signaling events in pollen tubes (PTs), guard cells (GCs), and mesophyll cells (MCs). Monitoring spatio-temporal relationships between membrane voltage, Ca2+- and pH-dynamics revealed interconnections previously not described. • In tobacco PTs, we demonstrated Ca2+-dynamics lag behind pH-dynamics during oscillatory growth, and pH correlates more with growth than Ca2+. In GCs, we demonstrated abscisic acid (ABA) to initiate stomatal closure via rapid cytosolic alkalization followed by Ca2+ elevation. Preventing the alkalization blocked GC ABA-responses and even opened stomata in the presence of ABA, disclosing an important pH-dependent GC signaling node. In MCs, a flg22-induced membrane depolarization preceded Ca2+-increases and cytosolic acidification by c. 2 min, suggesting a Ca2+/pH-independent early pathogen signaling step. Imaging Ca2+ and pH resolved similar cytosol and nuclear signals and demonstrated flg22, but not ABA and hydrogen peroxide to initiate rapid membrane voltage-, Ca2+- and pH-responses. • We propose close interrelation in Ca2+- and pH-signaling that is cell type- and stimulus-specific and the pH having crucial roles in regulating PT growth and stomata movement.

Electroactive dielectric polymer gel (DPG) as a class of electronic type electroactive polymers has important applications in soft robot, wearable electronics, and biomedical fields due to their lower driving voltage, degree of various actuation freedoms, and high actuation strain. The DPG materials are often composed of solid and liquid phases which are made by polymer network and high dielectric constant of solvent (or plasticizer). Accordingly, the electromechanical coupling mechanisms of DPGs are more complex and are different with other electronic electroactive polymers. In addition, the DPGs have many advantages for soft actuators such as lower driving voltage, larger actuation strain, and various actuation freedoms. As far as we know, the concept and progress of DPGs have not been systematically reported so far. In this review, we completely reviewed recent progresses of electroactive DPG materials, electromechanical coupling mechanisms, and applications of DPG actuators, etc. This review can provide more understanding, current challenges, and future trends of electroactive DPGs and their applications in soft actuators. Graphical abstract

Coal remains an important fuel and energy, especially in China. For coal mining in deep mines, the threat of coal and rock dynamic disasters (such as coal and gas outburst) to safe production is becoming more and more serious with the greatly increasing geo-stress and gas pressure. Hence, it is particularly important to real-timely monitor and finely identify outburst-hazardous zones and their hazard levels during coal mining. However, conventional methods fail to continuously and precisely monitor outburst-hazardous zones in spatial distribution. Previous studies have shown that under the coupling action of stress and gas, the electric potential (EP) signals can be generated and their response characteristics are closely related to the loading state and damage evolution process of coal. The inversion imaging method can be utilized to analyze the spatial distribution of the EP signals. On this basis, the field tests were conducted to study the EP response characteristics to the mining process of deep coal seams and analyze the relationship between the EP response and outburst hazard. Moreover, in view of the EP inversion imaging mechanism, the bilateral EP inversion n model was established on the mining-disturbed coal seam ahead of the mining face and the field application was also carried out. Furthermore, on account of the membership index of fuzzy mathematics, the critical EP inversion value was proposed. Then the outburst-hazardous zones in the coal seam ahead of the mining face were divided finely and identified quantitatively. In the end, the verification result showed that the yellow zones enable to identify most of outburst-hazardous zones, thus effectively avoiding the missing identification. Besides, the red zones can improve the identification efficiency, which is conducive to focusing on identifying zones with a high hazard level. The study results provide a valuable new application method for finely identifying coal and gas outburst hazards and preventing coal and rock dynamic disasters in deep coal mines.HighlightsThe EP signals response can reflect the stress state and damage evolution of coal seams.The bilateral EP inversion model was established ahead of mining face to reveal the electric field distribution characteristics.The EP inversion results could identify the hazardous zones of dynamic disaster for coal and gas outburst in the coal seam.

The control of material interfaces at the atomic level has led to novel interfacial properties and functionalities. In particular, the study of polar discontinuities at interfaces between complex oxides lies at the frontier of modern condensed matter research. Here we employ a combination of experimental measurements and theoretical calculations to demonstrate the control of a bulk property, namely ferroelectric polarization, of a heteroepitaxial bilayer by precise atomic-scale interface engineering. More specifically, the control is achieved by exploiting the interfacial valence mismatch to influence the electrostatic potential step across the interface, which manifests itself as the biased-voltage in ferroelectric hysteresis loops and determines the ferroelectric state. A broad study of diverse systems comprising different ferroelectrics and conducting perovskite underlayers extends the generality of this phenomenon.

Scalable production of freestanding borophene is of great importance for practical applications. Top-down approaches such as sono-chemical and electrochemical exfoliation are challenging due to complex structure and low electrical conductivity of boron. In this study, we envisaged to add multiwalled carbon nanotubes (MWCNTs) into boron powder to tackle the low conductivity of boron. A few layer borophene sheets down to 0.8 nm thickness were successfully prepared by anodic exfoliation of crystalline boron powder in Na 2 SO 4 . + 20 V was found to be the optimum exfoliation voltage as it results in thinner and larger sheets compared to higher voltage values. More than 50% of the exfoliated sheets are less than 10 layers, which indicate the potential of the process for freestanding borophene production. After the exfoliation process, MWCNTs could be effectively removed by a toluene/water system and subsequent filtration through a cellulose membrane. The method proposed here is scalable because the amount of boron powder that can be exfoliated can be increased without a limit as long as sufficient amount of MWCNTs are added to provide enough electrical conductivity. This novel strategy can also be extended to exfoliate other low conductivity materials, promoting future research. Graphical abstract

Piezoelectric materials derived from piezoelectrically inactive polymers and lead-free functional nanofillers have received a lot of attention for their ability to convert mechanical energy associated with various human body movements into electrical signals. Herein, the fabrication and performance of a novel thermoplastic polyurethane/nanohydroxyapatite electrospun composite membrane-based piezoelectric nanogenerator (PENG) is using polydimethylsiloxane (PDMS). The nanohydroxyapatite (nHA) and oxidized multiwalled carbon nanotube (o-MWCNT) fillers converted a non-piezoelectric PU polymer material into a piezoelectrically active composite material. Compared to pristine electrospun PU, every composite sample showed improved mechanical properties, thermal stability, dielectric properties, and piezoelectric characteristics. Dynamic-contact electrostatic force microscopy (DC-EFM) confirmed the piezo-ferroelectric characteristics of all composite samples. The nHA/o-MWCNT hybrid filler-modified optimized nanofibrous sample (PHAT) showed outstanding dielectric properties and piezoelectric characteristics. The PHAT-based PENG showed the highest stimuli-responsive output voltage in the 0.4–32 V range, whereas the pristine electrospun PU-based PENG showed only an output voltage of 0.08–5.75 V from various stimuli. The flexible PU electrospun composite membrane can be considered a new potential material for harvesting electrical energy from the mechanical energy associated with various human body motions. Graphical abstract

Li-rich manganese-based cathode materials are known as one of the most promising cathode materials for next-generation lithium batteries due to their high theoretical specific capacity. However, there are problems such as low specific capacity, poor rate performance, and fast decay rate during cycling. In this paper, spherical lithium-rich manganese-based cathode material Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 was prepared by co-precipitation method, and aluminum fluoride (AlF 3 ) was prepared by high temperature solid state reaction, so that AlF 3 was uniformly coated on lithium-rich manganese-based cathode. The results show that AlF 3 is uniformly coated on the surface of the spherical Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 material with a thickness of about 5~7 nm, and the material maintains the original layered structure without changing. The charge–discharge cycle test was carried out in the voltage range of 2.0~4.8 V, and the specific capacity of the Li-rich manganese-based cathode material coated with AlF 3 was significantly improved, reaching 283.3 mAh/g (Under the same preparation method and test conditions, this value is in the forefront of the 260–290 mAh/g that can be achieved by most of the current coating methods). The AlF 3 coating with the best retention performance is 4 wt% and still has a retention rate of 84.4% after 200 charge–discharge cycles. During the charging and discharging process, AlF 3 can maintain the stability of the main cathode material and inhibit the next transformation, thereby ensuring the high specific capacity and cycle stability of the material. Graphical abstract

Plasma-functionalized liquids (PFL) emerge as an effective sanitizer with great potential to be against a variety of microorganisms but their applications on seafood products are limited. In the current study, the physicochemical properties of plasma-functionalized water (PFW) and plasma-functionalized buffer (PFB), and their antimicrobial activities on grass carp, were investigated under different conditions of applied voltage, plasma exposure time and immersion time. Results indicated that increasing voltage and exposure time led to an increase in levels of reactive species in PFW and PFB, while the presence of citric acid in the buffer accelerated possible reactions of active species and enhanced acidification, electrical conductivity (EC) and oxidation-reduction potential (ORP) as compared with PFW. Results also showed that the decontamination efficiency depended on voltage and exposure time, which could be up to 1.21 and 1.52 log reductions for L. monocytogenes, and 1.44 and 1.75 log reductions for S. Typhimurium for PFW and PFB, respectively. Immersing fish fillet samples in both solutions also led to a reduced pH and increased total acidity level in the samples with no significant difference (p > 0.05) between PFW and PFB, while PFB greatly affected the colour change in fish fillets. This study provided a basis for the potential development of novel sanitizers to decontaminate microorganism in fish and seafood products.Key points• Cold plasma induced a time-dependent change of active species in water and buffer.• Ionic equilibria of conjugate base and weak acid in buffer enhanced RNS and ROS.• Decontamination depended on voltage and exposure time of liquids to cold plasma.• Reduced pH, increased acidity and colour change were noticed in treated fish.• A basis for developing potential sanitizers for seafood products is provided.