Decrease In Capacitance Research Articles

Development of Simple and Rapid Evaluation for Channel Proteins Embedded in Cell-Derived Vesicles Based on Dielectrophoretic Manipulation

Introduction Channel proteins in the plasma membrane play important roles in regulating the transport of specific molecules and ions in response to concentration differences between inside and outside cells. Therefore, the simple and rapid analysis of channel function and screening of agents for regulating the channel functions are desired in the research fields for pharmacology and drug discovery. Patch-clamp technique provides a unique and precise analysis for channel function. However, it has low measurement throughput to requires precise manipulation of a glass electrode to contact with a single cell. In this study, we applied the manipulation technique by dielectrophoresis (DEP) for easy and rapid evaluation of the opening and closing of channels embedded in Giant Plasma Membrane Vesicles (GPMVs). The time dependence of the fluorescence intensity of the internal dye of GPMVs, which were ordered well on the microwell array electrode by DEP was used to investigate the open/closed state of connexin, that is a channel protein expressed on the membrane of GPMVs. Furthermore, we revealed that the DEP behavior of GPMVs depends on the applied frequency and the open/closed state of connexins on GPMVs. Methods HeLa cells were transfected to express connexin 43 fused with FusionRed at the C-terminal (Cx-HeLa). The Cx-HeLa cells stained with Calcein-AM were incubated for 6 hours in an active buffer (10 mM HEPES, 2 mM CaCl2, 150 mM NaCl, 25 mM paraformaldehyde, 2 mM dithiothreitol, 125 mM glycine, pH 7.4). The active buffer containing GPMVs was exchanged to DEP medium (270 mM sucrose, 2 mM CaCl2, 50 mS m-1 in conductivity) by dialysis. The DEP device consisted of a bottom indium-tin-oxide (ITO) substrate with 10,000 microwells (16 µm in diameter and 10 µm in height) and a top ITO substrate mounted on the bottom substrate via a double adhesion tape (15 µm in thickness) (Fig. A). After GPMVs suspension was introduced in the DEP device, sine waves were applied to the top and bottom ITO substrates to induce DEP force to GPMVs. Results and Conclusion GPMVs were isolated from Cx-HeLa cells, and the mean diameter of GPMVs was 5.6 µm (S.D. 2.1 µm). It is known that connexin channels maintain the close state in the solution containing Ca2+ [1]. When an AC voltage of 800 kHz was applied, the GPMVs with the connexin closed were quickly trapped in the microwells. This indicates the attractive force to higher electric field regions, called positive dielectrophoresis (p-DEP), acted on the GPMVs. The outer solution of GPMVs arrayed by p-DEP was exchanged to the buffer without Ca2+ for opening connexins. The fluorescence intensity of GPMVs in the open connexin state decreased rapidly compared to that in the closed connexin state (Fig. B). This result indicates that the fluorescent dye diffused outside through the opened connexin.Next, the dielectrophoretic behavior of the GPMVs introduced into the device was investigated. When an AC voltage with 500 kHz was applied, the GPMVs with closed connexins moved to the center of four microwells (Fig. C). This result indicates that negative-DEP (n-DEP), the repulsive force from the higher electric field region was induced to GPMVs. The critical factor for identifying the electric properties of GPMVs is the cross-over frequency at which the n-DEP and p-DEP switch. The cross-over frequency was found to be between 500 kHz and 700 kHz for GPMVs with closed channels, while it was shifted to the region between 700 kHz and 800 kHz with open channels. The shift of cross-over frequency could be attributed to the decrease in membrane capacitance caused by the opening of the connexin channels. In conclusion, DEP manipulation of GPMVs could be useful for tracking single vesicles and easily discriminating the open/closed state of connexins embedded in the membrane.

Anion Exchange Membrane Water Electrolyzer Accelerated Durability Assessment Using Potential Cycling

Anion exchange membrane water electrolyzers (AEMWEs) have shown remarkable progress in terms of voltage efficiency and achievable current density in the past few years. Various methods are employed to assess the durability of AEMWEs at component and cell level, and include constant and cycled current/potential, start/stop cycles, and open-circuit-voltage (OCV) holds. Each technique may impose different levels of stress on individual components, and in cases have aimed to accelerate polymer degradation or to stress the catalyst or catalyst layer integrity. Particularly due to the more fundamental technology readiness level of AEMWE, it is essential to understand the degradation mechanism and failure modes at membrane electrode assembly (MEA) level.In this study, commercial AEM, ionomer, Co3O4 as anode and PtC as cathode catalysts were employed for fabricating MEAs. Square-wave and triangular-wave potential cycling were applied as operational-based stress tests to understand the impact of load cycling on degradation. Square-wave potential cycling appeared to accelerate catalyst layer degradation through ionomer oxidation, which lessened catalyst site-access and enhanced kinetics. On the other hand, triangular-wave potential cycling seemed to stress membrane (thinning) reducing the high frequency resistance (HFR). In both cycling patterns, the dissolution of cobalt (catalyst) and nickel from the porous transport layer (PTL) were observed by inductively coupled plasma-mass spectrometry (ICP-MS) analysis of the feed liquid. Moreover, a slight decrease in double layer capacitance supports degradation of catalyst layer. The motivation of this investigation was to mimic closely representative operation when directly integrated with renewable energy sources. The results discussed here may provide insight as to lifetime differences between different electrolysis technologies and provide pathways to develop stress tests for AEMWE systems and improve cell level durability. Figure 1

Notched Gate and Graded Gate Oxide Processing for Reduced Capacitance Application in RF MOSFETs

As the demands of RF applications are rising, optimization of internal MOSFETs capacitances is a key issue to improve the cut-off frequency. In this abstract we report the development of a novel N-MOS architecture processed on 8-inch SOI wafers. This architecture has a gate oxide with variable thickness along the channel and a reduced bottom gate length aiming at minimizing Gate to Drain/Source capacitance (1) (2). This improvement on Gate to Drain/Source capacitance mainly comes from a decrease in overlap capacitances as described in (3).The new process flow is composed as usual until Poly-Si gate etching. By controlling the species flow and process time during plasma etching steps, over etch at the bottom of the gate is performed (fig.1(a,b)). Poly-Si gate notching engineering is possible due to reduction of the passivation layer thickness at the bottom of the gate during plasma etch. As described in (4) the gate is first etched using a HBr/CL2/O2 chemistry until reaching close to the bottom of the gate, allowing the formation of a passivation layer made of SiOxCly and the anisotropy of the etch. To etch the remaining thickness HBr flow is augmented while CL2 and O2 flow are reduced, preventing formation of passivation layer. This leads to isotropic etch of the bottom gate and reduction of the gate length as regard to the top Poly-Si dimension. This over-etch reduces the physical gate length without changing the effective and the on-mask gate lengths, leading to overlap capacitance reduction.To produce gate oxide with variable thickness under gate sidewalls a two-steps process is performed. First, full plate oxide is grown before poly-Si deposition to act as middle gate thickness. Then undercut is performed, consisting of lateral etching of the gate oxide under gate sidewall after gate etch (fig.2.a). To achieve this undercut, hydrofluoric acid (HF) wet etch has been chosen. First trials with very low HF concentration become quickly saturated leading to small lengths under gate sidewalls (fig.2.b). Then more acidic solutions were used allowing satisfying undercut lengths (fig.2.c).Finally rapid thermal oxidation (RTO) is performed to obtain an oxide bird beak at both gate side as both Poly-Si gate and Si from the active region react with ambient O2 in the chamber. This leads to a gate oxide with variable thickness along the channel (fig.3(a.b)) which has both effects: to get smoother poly-Si foot and a down step in the active between channel and Source/Drain regions. During this process step, a built-in spacer on the gate sides for LDD implantation is formed. RTO process step has grown a thicker oxide over Source/Drain areas which has to be reduced to allow an accurate LDD implantation, this is done by anisotropic etching. After these new steps, the process goes back to a standard N-MOS process flow.Some early versions of the notched gate have been investigated (5), and these experiments and details on processing recipe seem promising for electrical results. As poly-Si foot has been smoothed and graded gate oxide (GGO) on top of overlaps region is formed. It would allow a reduction in parasitic capacitances improving cut-off frequency of RF applications.References RF LDMOSFET with Graded Gate Structure. Xu Shuming, Foo Pan Dow. Toronto : s.n., 2001. 1th International Symposium on Power Semiconductor Devices and ICs. ISPSD'99 Proceedings. pp. 221-224. DOI:10.1109. Notched-Gate pMOSFET with ALD TiN/High-κ Gate Stack Formed by Selective Wet Etching. Zhang, D. Wu and J. Lu and P.-E. Hellström and M. Östling and S.-L. s.l. : The Electrochemical Society, Inc., 2004, Electrochemical and Solid-State Letters, Vol. 7, p. 228. 10.1149/1.1795612. A simple efficient model of parasitic capacitances of deep-submicron LDD MOSFETs. Fabien Pregaldiny, Christophe Lallement,Daniel Mathiot. s.l. : Solid State Electronics, 2002, Vol. 46, pp. 2191–2198. https://doi.org/10.1016/S0038-1101(02)00248-4. Design of notched gate processes in high density plasmas. J. Foucher, G. Cunge, L. Vallier, and O. Joubert. s.l. : AVS: Science & Technology of Materials, Interfaces, and Processing, 2002, Vols. Journal of Vacuum Science & Technology B 20,. http://dx.doi.org/10.1116/1.1505959. Notched gate MOSFET for capacitance reduction in RF SOI technology. al, L. Antunes et. s.l. : 2023 IEEE International Conference on Design, Test and Technology of Integrated Systems (DTTIS), 2023. doi: 10.1109/DTTIS59576.2023.10348288. Figure 1

Synthesis and Photoelectrochemical Properties of Copper Titanate for Pollutant Removal

Copper species are considered one of the materials capable of converting pollutants in add-products values. However, its stability is a challenge when applied in photoelectrocatalytic (PEC) processes. A promissory alternative is to couple copper species with other materials improving their chemical stability, such as TiO2, an p-type semiconductor with excellent charge transfer. The insertion of Cu atoms into the titanium crystal lattice can promote the formation of stable binary copper oxides and/or the production of ternary/quaternary oxides by sharing oxygen between the species1,2. In addition, the presence of TiO2 on CO2 conversion may lead to the reactions for methanol and ethanol formation due to its property to favor the generation of hydroxyl radicals (OH•) and H+ from the oxidation of water. Then, in the present work carried out the preparation of n-type ternary oxide semiconductor based in copper and titanium oxides. Cu–O–Ti was synthesized by a time-efficient, arc-melting method from TiO2 and Cu2O. The particulate product showed in its composition mixture between TiCu2O3 / TiCu3O5 and high crystalline phase. These ternary oxides presented a broad-band absorption in the UV−visible spectral region with absorbance coefficient located at 675 nm. Also, the material showed thermal stability up to ∼475 °C, and cathodic photoelectrochemical activity. Controlled thermal oxidation of copper from the Cu (I) to Cu (II) oxidation state showed that the crystal lattice could accommodate Cu2+ cations up to ∼475 °C, beyond which the compound was converted to CuO and TiCuO3. This process was monitored by powder X-ray diffraction and X-ray photoelectron spectroscopy. The mott-Schottky plots for this ternary oxide exhibited a decrease of capacitance indicating an increase of CO2 absorbing active sites. The efficiency of photocatalyst was evaluated by PEC experiments to CO2 conversion into alcohols. The experiments were carried out bubbling CO2 in 1.0 Mol L-1 NaHCaO3. The ternary oxide favored the ethanol and propane formation, as the final product, exhibiting high selectivity and concentration. Keywords: ternary copper oxide, copper titanate, arc synthesis, p-type semiconductor, photoelectrochemistry, CO2 conversion, C2 products formation.

Electrochemical Assessments of Lithium Plating Reversibility on Graphite Anode in Lithium-Ion Batteries

In recent years, lithium-ion batteries (LIB) have been widely adopted as the power source for transportation systems, especially electric vehicles, owing to their superior energy and power densities. However, the extended charging time of LIB remains a significant barrier to the widespread adoption of electric vehicles. To address this problem, numerous studies have been conducted from a variety of perspectives (e.g., material, structure, charging algorithm) and as a result, the charging time of LIB has been significantly reduced. Despite these technological improvements, however, the reduced durability and safety of the LIB during fast charging remains an issue that needs to be addressed. Specifically, lithium plating on the anode surface during fast charging is a critical side reaction to avoid. The impact of lithium plating on battery performance can be broadly classified into three categories, based on how the lithium reacts after plating: lithium that is spontaneously intercalated into the active material after plating and then deintercalated during discharge; lithium that remains in the plated form and is oxidized during subsequent discharge; lithium that remains in the plated form but is unable to react during subsequent discharge. The first two are termed reversible lithium plating as they contribute to the capacity while the last is referred to as irreversible lithium plating because it does not participate in the subsequent discharge reaction. Irreversible lithium plating typically results in loss of lithium inventory, increased internal resistance, and can even cause internal short circuits if lithium electrodeposits accumulate with repeated charge and discharge. Therefore, research on lithium plating during fast charging should place greater emphasis on detecting irreversible lithium plating and analyzing its effects. Among lithium plating detection methods, electrochemical techniques are particularly noteworthy, because they can analyze the lithium plating/stripping in real-time without dismantling the battery. However, existing studies using electrochemical methods were primarily focused on determining the presence or absence of plated lithium on the anode and rarely discussed irreversible lithium plating.In this presentation, we propose an electrochemical method for detecting and quantifying irreversible lithium plating on the anode during LIB charging. For this purpose, lithium was initially plated onto graphite anode under different charging conditions, and the lithium morphology was analyzed through stereological image analysis. The morphology analysis showed that the porosity and surface area of the plated lithium increased with higher charging rates, indicating that the mechanical strength of the lithium is weaker when plated at higher charging rates. It was also observed that the lithium deposit layer shrank in the open circuit state immediately after charging, resulting in a decrease in the overall volume of the plated lithium. From the electrochemical assessments, including interfacial capacitance, open circuit voltage, and irreversible capacity, it proved that as the charging rate increased, the capacitance increased and the degree of capacitance decrease over time also increased in the open-circuit state immediately after charging. Furthermore, it was confirmed that the time period of flat relaxation voltage closely coincided with the time period of capacitance reduction and plated lithium shrinkage. By determining the irreversible capacity through discharge capacity analysis, the amount of irreversible lithium plating was estimated and found to be linearly related to the degree of capacitance reduction. This strongly suggests that the amount of irreversible lithium plating can be quantified by the degree of capacitance reduction over time in the open circuit state immediately after lithium plating. In this presentation, we will describe an electrochemical technique for analyzing the evolution of the plated lithium over time and propose a method for detecting irreversible lithium plating. Furthermore, we will discuss in detail the correlation between the interfacial capacitance and irreversible capacity, and present the possibility of quantifying irreversible lithium plating by an interfacial capacitance analysis.

Исследование проницаемости эпителиального слоя клеток TEER методом

The study investigated the electrical characteristics of the Caco-2 cellular layer grown on a cellulose acetate membrane using impedance spectroscopy and cyclic voltammetry methods. The effect of ethanol solutions of varying concentrations on the electrophysical properties of the cellular layer was studied. During measurements of the layer characteristics by the cyclic voltammetry method under direct current, it was found that its resistance before ethanol treatment was 642 kOhm. Treatment with a 25% ethanol solution increased this value to 645 kOhm, while 50% and 95% solutions decreased it to 505 kOhm and 373 kOhm, respectively. During the study of the cellular layer's properties using impedance spectroscopy with alternating current, dependencies of the real and imaginary parts of the resistance on the ethanol concentration in the treatment solution were obtained. The obtained data were used to construct Nyquist diagrams. Their analysis allowed for the proposal of an equivalent circuit describing the process of current flow through the studied system. The equivalent circuit included parameters of paracellular transport, membrane resistance and capacitance, as well as elements accounting for electrode polarization. As a result, values of capacitance and membrane layer resistance were obtained. It was established that the membrane layer capacitance changes under the influence of ethanol. When treated with a 50% ethanol solution, capacitance increases, indicating degradation of the cell membrane and a reduction in its barrier function. Treatment with a 95% solution led to a decrease in capacitance, which can be attributed to the compression of the cell layer, reducing the capacitance contribution to the system's overall conductivity. The results demonstrate the importance of quantitative analysis of cellular electrical parameters for studying their response to chemical stress and confirm the potential of such approaches in biomedicine for creating sensors and «organ-on-a-chip» systems.

Exploring the bio-inspired corrosion inhibition properties of eco-friendly Limonia acidissima leaves extract for mild steel in acidic media: Computational, electrochemical and spectroscopic insights

This study investigates the corrosion inhibition properties of Limonia acidissima leaves extract (LALE) on mild steel in a 1.0 M HCl medium. Utilizing mass loss measurements, potentiodynamic polarization, AC impedance spectroscopy, and surface characterization methods like SEM, AFM, UV–Vis, and fluorescence spectroscopy, the study reveals significant findings. The maximum inhibition efficiency of LALE was attained to be 92.26 % at a 1.0 % concentration. Potentiodynamic polarization studies show a marked decrease in corrosion current density (Icorr) from 3.102 × 10–3 A/cm² for the blank solution to 3.165 × 10–4 A/cm² with 1.0% LALE, indicating mixed-type inhibition. AC impedance measurements show an increase in charge transfer resistance (Rct) from 2.1410 Ω in the blank solution to 8.6580 Ω with 1.0% LALE, and a decrease in double-layer capacitance (Cdl) from 7.757 × 10–7 μF/cm² to 1.926 × 10–7 μF/cm², suggesting the formation of a protective film. SEM and AFM analyses confirm that LALE-treated steel surfaces are smoother with fewer pits and cavities compared to untreated steel. Furthermore, DFT analysis complemented well with the empirical findings. This research highlights the potential of plant extracts in industrial applications for corrosion protection, contributing to the growing body of knowledge on sustainable corrosion inhibitors and offering practical insights for future research and application in various corrosive environments.

Electrochemical performance of MWCNT nanowires-decorated ZnCo2O4 sphere nanocomposite for an asymmetric capacitor

A composite material consisting of porous ZnCo2O4 sphere covered with MWCNT nanowires is synthesised using a hydrothermal technique and thermal annealing. The capacitive properties of the electrode materials are examined. The ZnCo2O4/MWCNT composites have superior capacitive performance in comparison to pure ZnCo2O4 hexagonal nanoplates. The ZnCo2O4/MWCNT composites have a specific capacitance of 2080 F/g at 1 A g−1. The cells also exhibit outstanding rate capacity, maintaining 600 F/g even at 5 A g−1. The nanocomposites have exceptional retention rate, as seen by an only 4.7 % decrease in specific capacitance over 10,000 cycles. The improved capacitive efficiency of ZnCo2O4/MWCNT composites may be ascribed to the structural benefits of large surface area, excellent electrical characteristics, and a well-established network provided by the MWCNT support. The ASC device has a significant energy density of 52.74 Whkg−1 while operating at a power density of 4205 Wkg−1. Additionally, it has an operating voltage window of 0–1.6 V. The excellent capacitive performance shows the potential use of ZnCo2O4/MWCNT composites as electrodes for hybrid capacitors.

Li-ion solvation structure at electrified solid-liquid interface: Understanding solvation structure dynamics and its role in electrochemical energy storage through binary ethylene carbonate and dimethyl carbonate solvent.

Binary solvent electrolytes can provide interpretations for designing advanced electrolytes of next generation batteries. This study investigates the adsorption mechanisms of solvated lithium ions in binary solvents near charged electrodes. Molecular dynamic simulations are performed for lithium hexafluorophosphate (LiPF6) in ethylene carbonate and dimethyl carbonate (EC:DMC) solvent sandwiched between two electrodes. Results show that lithium ions form a tetrahedral solvation structure with two EC and two DMC molecules. The solvated lithium ion shows anti-electrostatic interaction with electrodes. This can be attributed to the electrostatic attraction of the polar end of the DMC molecule, which keeps the cation anchored to the positive electrode. Meanwhile, the solvation structure adopts a fix orientation at the negative electrode, which leads to unchanged electrostatic interaction at high charge density. Finally, EC molecules are swapped by DMC molecules near the negative electrode at high charge density. This leads to a decrease in local relative permittivity and, therefore, a decrease in differential capacitance. The differential capacitance of the positive electrode continuously decreases with increasing charge density. This is caused by the partial anchoring of solvent molecules holding the cations, which cancels the adsorption of anions near the positive electrode. This study provides insights into designing better electrolytes for efficient battery performance.

Characterization of Mn3O4/(x)Nb2O5 thin films as a promising material for supercapacitors

The thin films of Mn3O4/(x)Nb2O5 oxides (x = 0, 2, 4, and 6 %) were prepared by the electron beam evaporation method and then annealed at 400 °C. The structural analysis showed a tetragonal phase of Mn3O4, according to X-ray diffraction results. The quantitative elemental analysis of films confirms the stoichiometry of the Mn3O4, while the Nb2O5 couldn’t be recognized using energy dispersive X-ray fluorescence. The chemical speciation of the films was investigated using X-ray photoelectron spectroscopy. Three oxidation states of Mn were recognized at average binding energies of 645.70±0.35, 642.99±0.40, and 641.58±0.48 eV that correlated to Mn4+, Mn3+, and Mn2+, respectively. As the Nb2O5 increases, a slight decrease in the binding energy of Mn4+ is recognized, whereas it is nearly constant for the deconvoluted Mn3+ and Mn2+. Two electronic transitions (Eg1 and Eg2) of the optical band gap showed an increase with increasing Nb2O5 dopant from 2 % to 6 %. The optical parameters such as Eosc, the single oscillator energy, Edis, the dispersion energy, both moments (M−1) and (M−3), the ratio of carrier concentration/effective mass (N/m*), and the lattice dielectric constant (εL) were determined. From electrochemical measurements of pure Mn3O4 films, it is found that the voltammetric current density is directly proportional to the scan rates of cyclic voltammetry CV, with good cyclic stability, and by increasing the scan rates, the values of specific capacitance decrease while the values of specific power increase. In doped thin films, no potential drop is observed in the discharging process, which indicates good interfacial contact between the active material and the substrate during the charge/discharge process. These results suggest that the obtained Mn3O4 nanoparticles are a better candidate for supercapacitor applications.

Impact of voltage and frequency on electrical characteristics of MIS capacitors with triphenylamine layer

This study examines the effect of triphenylamine (TPA) interlayers on the electrical properties of Al/TPA/p-Si metal-interlayer/insulator material-semiconductor (MIS) capacitors. Using Gaussian software, TPA molecular structure was optimized, and HOMO-LUMO energy levels were simulated. Capacitance-conductance-voltage (C-G-V) measurements were performed at room temperature over −4 V to +4 V and 50 kHz–700 kHz. AFM and SEM analysis showed TPA films were smooth with a uniform thickness of about 178 nm. The C-V characteristics revealed a frequency-dependent decrease in capacitance, indicating a continuous distribution of interface states. Barrier height (ΦB) increased from 0.305 eV at 50 kHz to 0.655 eV at 700 kHz, while the active interface trap density (Dit) decreased from 6.73 × 1012 eV−1 cm−2 to 3.23 × 1011 eV−1 cm−2. Additionally, the accumulating region exhibited low series resistance values (between 6.88 and 8.44 Ω). These results suggest that TPA thin films are effective for MIS capacitors.

Enhanced Schottky barrier engineering in silver-doped TiO2/p-Si heterojunctions: Insights into electrical behavior and charge carrier dynamics

Heterojunctions were fabricated through the deposition of silver-doped Titanium dioxide (Ag–TiO2) onto p-type crystalline silicon, employing the sol-gel technique. Electrical characterization was conducted with varying Ag concentrations. The investigation revealed that the Schottky barriers at each interface (Ag/TiO2 and Si/Ag), along with the built-in potential at the TiO2/p-Si junction, increase proportionally with the Ag concentration. This observed trend was attributed to the reduction in the TiO2 bandgap due to Ag incorporation, resulting in a concurrent shift in both valence and conduction bands. Consequently, there is a growth of the conduction energy discontinuity and a reduction in the valence one, facilitating hole diffusion while impeding electron transfer across the depletion layer. Furthermore, the introduction of Ag leads to a decrease in both electron and hole concentrations. However, Ag incorporation within the TiO2 matrix manifests as nanoparticles and clusters, resulting in a nonhomogeneous distribution of charge carriers across the sample. Impedance analysis indicates an increase in device resistance and a decrease in effective capacitance.

Comprehensive study on the corrosion inhibition of aluminum in HCl by N1, N1'-(ethane-1,2-diyl)di(ethane-1,2-diamine): Experimental and theoretical approaches

The inhibitory effects of the novel molecule N1, N1'-(ethane-1,2-diyl)di(ethane-1,2-diamine) (TETA) on aluminum (Al) corrosion were investigated in 0.2, 0.3, and 0.4 M HCl solutions. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), quantitative techniques, and surface morphology characterisation were utilised. Surface morphology characterisation via atomic force microscopy (AFM) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) confirmed the efficacy of the inhibitor in preventing corrosion. Weight loss research revealed that the protective efficacy of TETA grows with increasing concentration but shrinks with increasing temperature of the acidic solution. The findings indicate a marked increase in inhibition efficiency as TETA content rises, reaching 99.0 % when measured by the weight loss method, 98.34% through EIS, and 94.13% via electrochemical polarization. Polarization curves show that TETA stops hydrochloric acid from acting on the anodic type. Both the charge-transfer resistance and the double-layer capacitance decrease with increasing inhibitor concentration, as shown by the adsorption mechanism and supported by the EIS results. "The Langmuir isotherm and negative Gibb's free energy values demonstrate that the inhibitor molecules cling to the metal and that they adsorb to the aluminium spontaneously. In addition to analysing TETA via density functional theory (DFT), the adsorption of TETA on the surface of aluminium (Al) was examined via molecular dynamics (MD) simulations. The results show that the TETA molecule successfully blocks the corrosion process.

Rapeseed cake meal extract as an eco-friendly green sustainable inhibitor for the corrosion of cold rolled steel in trichloroacetic acid solution

The inhibitory properties of rapeseed cake meal extract (RCME) on the corrosion of cold rolled steel (CRS) in trichloroacetic acid (TCA) were systematically investigated using gravimetric, electrochemical, surface characterizations and theoretical calculations. The results demonstrate that RCME exhibits excellent inhibitory performance with a maximum inhibition efficiency of 92.7 % for 100 mg L−1 RCME at 20 °C. The adsorption of RCME obeys Langmuir isotherm at 20 and 30 °C, Temkin isotherm at 40 °C, and Freundlich isotherm at 50 °C. RCME acts as a cathodic inhibitor. The charge transfer resistance is increased with the addition of RCME, while the double-layer capacitance decreases. SEM, AFM, CLSM, XPS, XRD and TOF-SIMS analyses confirm that the active components in RCME adsorb onto the surface of CRS, forming a protective film that effectively inhibits the corrosion of CRS by TCA. Along with the increase in the concentration of RCME, the surface tension of the inhibited solution gradually decreases, while the electrical conductivity increases before stabilizing. HPLC-MS and FTIR analyses reveal rutin, linolenic acid, linoleic acid and adenine are the effective substances in RCME. Quantum chemical (QC) calculations and molecular dynamic (MD) simulations indicate that the active centers of the effective inhibitor molecules are predominantly located on benzene rings, O- or N-containing heterocyclic rings, and functional groups such as C=O and C=C. Additionally, their main chains adsorb onto the Fe (001) surface in an approximately flat manner, involving both chemical and physical adsorption processes.

Optimized Preventive Diagnostic Algorithm for Assessing Aluminum Electrolytic Capacitor Condition Using Discrete Wavelet Transform and Kalman Filter

Power converters (PCs) are vital elements of critical applications, making their reliable operation crucial. Enhancing PCs’ reliability can be achieved by adding intelligence to the system, enabling it to predict failures and generate early warnings before a failure occurs. In this context, intelligence is integrated into the system through preventive diagnostic algorithms (PDAs) that assess the converter condition. This article introduces a PDA designed to determine the optimal replacement timing for aluminum electrolytic capacitors (AECs) within power converters. AECs, in addition to being a fundamental component of PCs, also represent the most vulnerable element of the PCs’ power section. The aging of AECs is characterized by a decrease in capacitance (C) and an increase in the equivalent series resistance (ESR). Therefore, ESR and C serve as key indicators for assessing the AECs’ health status. One of the most critical functional requirements for designing a PDA is its accuracy, which can be significantly affected by transients. The solution proposed in this paper is resilient to transients, overcoming a common problem in implementing AECs’ PDAs. The proposed algorithm employs discrete wavelet transform (DWT) to extract the converter signal modes. Subsequently, key characteristics of these modes are extracted, enabling the calculation of both ESR and C. Finally, by using the estimated ESR and C values, two fault indicators can be obtained that are resilient to transients. Employing a Kalman filter reduces noise and ensures the indicators’ resilience to transients, making them highly effective for evaluating the AECs’ health status. The proposed PDA was validated through multiple computer simulations conducted in MATLAB/Simulink for a three-phase interleaved boost converter (3ϕIBC), which includes a proportional-integral (PI) controller with anti-windup capability.

Effect of Interfacial Ionic Defects in Perovskite Solar Cells and their Mitigation Mechanism: A Comprehensive Theoretical Analysis with Experimental Validation

AbstractInterfacial ionic defects in perovskite solar cells (PSCs) significantly influence the efficiency and long‐term stability. In this study, primarily simulation‐assisted analyses are conducted to explore the capacitive effect of these defects on the performance of PSCs through impedance analysis. Simulated data indicate a decrease in capacitance with increasing frequency, leading to a higher built‐in potential (ΔVbi = 150 mV). Moreover, an increase in capacitance with increasing light intensity is observed. Additionally, reducing the ionic defect concentration at the interfaces (from 1019 to 1016 cm−3) results in more significant band bending and a higher Vbi. Potential solutions to mitigate interfacial ionic defects, including doping at transport layer interfaces are proposed. Doping at both interfaces introduces an energy spike (valence band offset) of 0.21 eV and a cliff (conduction band offset) of 0.16 eV, respectively, for holes and electrons, leading to an improvement in the open circuit voltage (VOC). Finally, experimental results demonstrate a notable enhancement in VOC of 0.04 V with the introduction of Li+ doping at the electron transport layer/perovskite interface. These findings provide essential perceptions for effectively mitigating the effect of interfacial ionic defects on the performance of PSCs and enhance their overall performance.

Anticorrosive activity of Melothria perpusilla: A renewable and sustainable inhibitor

Anticorrosive activity of Melothria perpusilla extract on mild steel in H2SO4 was examined by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy methods. The results revealed that mild steel corrosion was effectively controlled by the extract with 99.4 % efficiency at 3000mg/L concentration. The efficiency was improved with higher extract concentration but decreased as the temperature increased. The Tafel plots and its corrosion potential value (<85 mV) inferred that Melothria perpusilla acts as a mixed type inhibitor. Adsorption of phytochemicals onto the surface of mild steel is the primary factor in reducing corrosion. The increase in activation energy for adsorption from 22.73 kJ mol−1 in acid to 133.74 kJ mol−1 in extract's presence confirms the active role of phytochemicals in adsorption process. The increase in charge transfer resistance from 3.21 Ω cm2 in acid to 369.2 Ω cm2 in extract's presence, coupled with a decrease in double layer capacitance in the EIS investigation, suggests that a charge transfer mechanism is active at the mild steel-solution interface. Gas chromatography-Mass spectroscopy revealed the presence of five major phytochemicals along with other organic compounds in the extract. Fourier transform infrared and UV–visible spectroscopies indicated the active functional moieties (-COOH, –CONH2, -C-O-C-, –C=C- and long chain alkyl groups) are involved in the inhibition. Scanning electron microscopy confirmed the existence of shielding film of phytochemicals on mild steel. Density functional theory validated the inhibitory properties of the constituents. Therefore, it is concluded that Melothria perpusilla is an efficient green inhibitor in acidic condition.

Suppression of irradiation effect on electrical properties of silicon diodes by iron in p-silicon

Radiation-hardness of silicon (Si) has been the subject of interest due to the damage of the material-based detectors during and after operation. In this work, the effects of 4 MeV proton-irradiation on the electrical properties of devices fabricated on undoped and Fe-doped p-Si were investigated using current-voltage (I-V) and capacitance-voltage (C-V) techniques. A decrease in current and capacitance is less pronounced and the conduction mechanism remains unchanged on Fe-doped p-Si diode after proton-irradiation. This insignificant change of electrical parameters of the Fe-doped diode after proton-irradiation indicates the suppression of the radiation effect by Fe in Si. The electrical properties of the diode are less dependent on incident radiation, because of the possible prevention of further dislodgement of atoms by incident radiation. As a result, the material becomes resistant to radiation damage, making the electrical properties of the diode independent of incident radiation due to Fe atoms in Si. As a result of the ohmic behaviour displayed by the Fe-doped Si diode, it is possible that in Si, Fe is responsible for generation-recombination (g-r) centres, which are defect levels positioned at the middle of the energy gap of Si. The possibility of these defects being responsible for the suppression of the radiation effect is explained in this work, making Fe a promising dopant to improve the radiation-hardness of Si.

Electrochemical Investigation of the Stability of Poly-Phosphocholinated Liposomes.

Poly[2-(methacryloyloxy)ethyl phosphorylcholine] liposomes (pMPC liposomes) gained attention during the last few years because of their potential use in treating osteoarthritis. pMPC liposomes that serve as boundary lubricants are intended to restore the natural lubrication properties of articular cartilage. For this purpose, it is important that the liposomes remain intact and do not fuse and spread as a lipid film on the cartilage surface. Here, we investigate the stability of the liposomes and their interaction with two types of solid surfaces, gold and carbon, by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). With the aid of a hydrophilic species used as an electroactive probe in the solution, the charge transfer characteristics of the electrode surfaces are obtained. Additionally, from EIS, the capacitance characteristics of the surfaces are derived. No decrease of the peak currents and no displacement of the peak potentials to greater overpotentials are observed in the CV experiments. No decrease in the apparent capacitance and increase in the charge transfer resistance is observed in the EIS experiments. On the contrary, all parameters in both CV and EIS do change in the opposite direction. The obtained results confirm that there is only physical adsorption without fusion and spreading of the pMPC liposomes and without the formation of lipid films on the surfaces of both gold and carbon electrodes.

Influence of Oxygen Vacancies Introduced via Acceptor (Gadolinium) Doping to the Pseudocapacitive Properties of Nano-Sized Cerium Oxide.

The voluntary introduction of defects can be considered an effective strategy for enhancing the electrochemical properties of metal oxide electrodes. In this study, the enhanced pseudocapacitive properties of an acceptor (Gd) doped cerium oxide nanoparticle-a sustainable metal oxide with low environmental and human toxicity-are investigated in depth using ex situ X-ray photoemission spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Interestingly, with 15at% Gd doping (15GDC), the specific capacitance of the nanoparticles measured at 1Ag-1 enhanced to 547.8Fg-1, which is fivefold higher than undoped CeO2 (98.7Fg-1 at 1Ag-1). The rate-dependent capacitance is also improved for 15GDC, which showed a 31.0% decrease in the specific capacitance upon a tenfold increase in the current density, while CeO2 showed a 49.9% decrease. The enhanced electrochemical properties are studied in depth via ex situ XPS and EIS analysis, which revealed that the oxygen vacancies at the surface of the nanoparticles played important roles in enhancing both the specific capacitance and the high-rate performance of 15GDC by acting as the active site for pseudocapacitive redox reaction and allowing fast diffusion of oxygen ions at the surface of 15GDC nanoparticles.