Electrical Performance Research Articles

Transvenous extraction of conduction system and lumenless pacing leads.

Conduction system pacing (CSP), often accomplished with lumenless pacing leads, is increasingly employed to achieve physiologic ventricular activation. There are limited data on the extraction of these leads. The objective of this study was to describe the safety and efficacy of extraction of CSP pacing leads and compare outcomes with extraction of non-CSP lumenless leads. Patients undergoing CSP/non-CSP lumenless lead removal were included. Outcomes of interest included rates of complete procedural success, complications, and successful reimplantation. Overall, 23 patients were included (n = 14 with CSP and n = 9 with non-CSP lumenless leads implanted in the right atrium, right ventricle, or septum). The mean age was 52.7 ± 24.0 years, 30% were female, and the mean lead age was 4.5 ± 4.4 years. The complete procedural success rate was 100%. One serious complication occurred in the non-CSP group but was unrelated to the lead of interest. Manual traction alone was successful in 57% of CSP cases (mean lead age 2.4 ± 1.7 years) and in 11% of non-CSP cases (mean lead age 7.9 ± 5.3 years). Laser sheaths were used in 43% of CSP cases and 89% of non-CSP cases; rotational cutting tools were used in no CSP cases and in 33% of non-CSP cases. Reimplantation in the conduction system was attempted with a left bundle branch pacing lead and successful in 80% (n = 4/5). Extraction of CSP and non-CSP lumenless leads is feasible with a high success rate and a good safety profile. CSP reimplantation after extraction is also feasible with good electrical performance.

A multilevel resistive switching memristor based on flexible organic–inorganic hybrid film with recognition function

Abstract Brain-inspired neuromorphic computing systems fueled the emergence of memristor-based artificial synapses, however, conventional silicon-based devices restricted their usage in the wearable field because of their difficulty in bending. To tackle the above challenge, a vertically structured flexible memristor with aluminum-based hydroquinone organic–inorganic hybrid film and Al2O3 as the functional layer, ITO and Pt as the bottom and top electrodes, and PET as the substrate has been developed utilizing molecular/atomic layer deposition to achieve a tradeoff between the resistive transition properties and the flexibility of memristors. The obtained devices combine stable resistive switching behavior and flexibility, showing high switching ratio of 103, better retention (up to 105 s) and endurance properties (up to 104 cycles), and robustness at radius of curvature of 4.5 mm after 104 bending cycles. Furthermore, the presence of multilevel resistive states in these devices ensures that the memristor can emulate synaptic properties such as paired-pulse facilitation, transition from short-term plasticity to long-term plasticity, long-term potentiation and depression, and spike-time-dependent plasticity. The resistive switching mechanism and the role of the bending state on the electrical performance of the device are explored. The fully connected artificial neural network based on the memristor can achieve a recognition accuracy of 90.2% for handwritten digits after training and learning. Flexible memristor will bring feasible advances to the integration of neuromorphic computing and wearable functionality.

Mechanical and Electrical Conductivity Properties of Graphene/Cu Interfaces: A Theoretical Insight.

For graphene/copper (Gr/Cu) composites, achieving high-quality interfaces between Gr and Cu (strong interfacial bonding strength and excellent electron transport performance) is crucial for enabling their widespread applications in electronic devices. This study employs first-principles calculations and the nonequilibrium Green's function method to systematically investigate the mechanical and electrical conductivity properties of Cu(111)/Gr/Cu(111) interfaces with various stacking sequences and different forms of Gr. For these interface systems, the binding energy, separation work, charge transfer, and electrical conductivity across the interface were obtained. The results show that the top-fcc interface exhibits superior interfacial properties, characterized by relatively high binding energy (-3.00 eV/C atom) and separation work (≥0.78 J/m2), a small interfacial distance (2.85 Å), and enhanced electron transport capacity (2.12 G0/nm2). A bilayer form of Gr significantly reduces electronic conductance across the Gr/Cu interface by nearly 2.46 orders of magnitude. Furthermore, point defects in Gr, especially single-vacancy defects, disrupt the traditional trade-offs between mechanical and electrical performance, simultaneously enhancing mechanical performance by 7.50-124.36% and electrical performance by 33.02%. Additionally, stress mechanisms have been proposed to further enhance the interfacial electrical conductivity of Gr/Cu composites. The present study provides a theoretical basis for exploring the engineering applications of Gr/Cu composite materials.

Deciphering the piezoelectric and conductive mechanisms of Nb-doped Bi3Ti1.5W0.5O9 high-temperature piezoelectric ceramics

The study utilizes Bi3Ti(1.5-x)NbxW0.5O9 (BTW-xNb, x=0.00, 0.01, 0.02, 0.04, 0.06) bismuth layered piezoelectric ceramics synthesized via a conventional solid-phase reaction process. This is the study to investigate the impact of B-site Nb ion doping on the structural and electrical properties of BTW-xNb ceramic. The results show that all ceramics have a single bismuth layer structure, with reduced lattice distortion according to Rietveld refinement findings. The presence of oxygen vacancies in the ceramic is the main factor that affects the high temperature conductivity of the samples. The XPS results, the increase in the activation energy of AC and DC conductivity confirm that doping with Nb5+ ions reduces oxygen vacancy concentration. The ceramics with the highest overall electrical performance are the BTW-0.02 Nb ceramics. Notably, the DC resistivity at 500 °C was enhanced from 9.16 × 105 Ω·cm (x = 0.00) to 8.24 × 106 Ω·cm. The TC was enhanced from 730 °C(undoped) to 743 °C. At 500 °C, tanδ decreases from 21.1 % to 8.2 %. The ceramic's increased resistivity increases the polarization voltage, resulting in more complete polarization. The d33 is increased from 7.5 pC/N (undoped) to 13 pC/N. Furthermore, the piezoelectric properties remain stable up to 700°C, suggesting that the material has considerable potential for use at elevated temperatures.

Laser-Induced Self-Limiting Welding of Ag Nanowires with High Mechanical and Electrical Performance.

The high-efficiency and high-precision welding technology of Ag nanowires is of great engineering significance for the integration of new-generation micro- and nanodevices, and the mechanical behavior of its interconnect joints is also essential for their reliable application, especially for some flexible device. In this paper, based on the nano-focusing and localized plasma enhancement properties of Ag nanowires under laser irradiation, Ag nanowire self-limiting joints with mechanical and electrical properties comparable to those of the base material are obtained. At the same time, the local plasma enhancement characteristics of Ag nanowire joints are scanned and analyzed with nanoscale resolution by using cathodoluminescence technology, and the local multi-physical field coupling regulation mechanism of Ag nanowire joints induced by different laser parameters is systematically investigated by combining theoretical simulations. Meanwhile, based on the in situ laser welding and nanomechanical tensile experiments, the mechanical properties of single Ag nanowires and their welded joints are systematically analyzed, and the characteristics of the interfacial atomic behaviors and the evolution process during the welding and tensile processes are investigated.

Enhanced Oxidation Resistance and Interface Stability of Atomic-Layer-Deposited MoNx Electrodes via TiN Passivation for DRAM Cell Capacitor Applications.

The continuous miniaturization of dynamic random-access memory (DRAM) capacitors has amplified the demand for electrode materials featuring specific characteristics, such as low resistivity, high work function, chemical stability, excellent interface quality with high-k dielectrics, and superior mechanical properties. In this study, molybdenum nitride (MoNx) films were deposited using a plasma-enhanced atomic layer deposition (PEALD) employing bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride and NH3 plasma for DRAM capacitor electrode applications. Depending on the deposition temperatures of the PEALD MoNx films ranging from 200 to 400 °C, the Mo/N ratio and crystal structure varied, transitioning from the cubic NaCl-B1-type MoN phase with Mo/N ratio of 1.4 to the cubic γ-Mo2N phase with Mo/N ratio of 1.9. Notably, MoNx films grown at 400 °C exhibited low resistivity (435 μΩ·cm), a high work function (5.28 eV), and superior mechanical hardness (11.3 GPa) compared to ALD TiN films. Despite these excellent properties, the PEALD MoNx electrode demonstrated insufficient chemical stability, particularly in terms of oxidation resistance and interface quality with ALD HfxZr1-xO2 (HZO) films. This resulted in poor morphology and the formation of significant oxygen-deficient HZO layers (such as HfO2-x), leading to considerable degradation in the electrical performance of metal-insulator-metal (MIM) capacitors. To mitigate this issue, a thin (2.5-14 nm) ALD TiN layer was introduced as a passivation layer between the MoNx bottom electrode and HZO dielectric. The TiN-passivated MoNx (TiN/MoNx) electrode showed substantially enhanced oxidation resistance and reduced interfacial reactions with the HZO dielectric. Consequently, MIM capacitors with TiN/MoNx bottom electrodes demonstrated outstanding electrical performance, including excellent dielectric properties, low leakage current density, and high mechanical strength. Hence, this study proposes a promising candidates for storage nodes in the next-generation DRAM capacitors.

Synergistic regulation of Nd2O3 doping and components accommodation to attain enhanced electrical performance in BiScO3-PbTiO3 high temperature ceramics

Nd2O3-modified BiScO3-PbTiO3 (Nd: BS-PT) ceramics were synthesized with the aim of augmenting the piezoelectric response. A comprehensive investigation was conducted to explore the impact of Nd and PT content on the structure, microstructure, and electrical properties of Nd: BS-PT ceramics. The introduction of Nd ions resulted in notable enhancements in the piezoelectric and dielectric properties of BS-PT ceramics. In the case of 0.02Nd: BS-0.64PT, the piezoelectric coefficient (d33) reached an impressive 550 pC/N. Furthermore, the room-temperature dielectric constants exhibited a continuous increase with rising Nd content. The relaxation behavior demonstrated a progressive augmentation corresponding to the increased Nd content. Conversely, both saturation polarization and remnant polarization exhibited a gradual decline with increasing Nd content. These variations are attributed to the refined microstructure and enhanced relaxation behavior induced by Nd doping. This innovative Nd: BS-PT ceramic demonstrates that judicious incorporation of Nd can markedly enhance the piezoelectric properties of BS-PT ceramics. Such a modification significantly augments the performance of BS-PT ceramics across various applications, notably in sensors and actuators.

2D g-C3N5 p-Doping of Donor Material for High-Efficiency Organic Solar Cells.

Molecular doping of organic semiconductor is a great strategy for significantly regulating the electronic band structure of organic semiconductor while increasing charge mobility and carrier concentration. Here, a facile strategy is presented by introducing 2D g-C3N5 as a p-dopant into PM6, improving the charge mobility and hole carrier concentration of PM6. Moreover, the electron transfer between PM6 and g-C3N5 can effectively downshift the Fermi energy level and highest occupied molecular orbital (HOMO) energy level of PM6, which leads to the increase the built-in electric field of organic solar cells (OSCs). The addition of g-C3N5 also effectively enhances the crystallization of active layer, thereby improving the stability of OSCs. As a result, a champion bulk-heterojunction (BHJ) and layer-by-layer (LbL) structure OSCs are successfully achieved featuring a high-power conversion efficiency of 18.10%/18.25%, simultaneously having excellent device stability. This work shows that introducing a low concentration dopant into organic donor is an effective method for improving the electrical performance of organic donor and the efficiency of OSCs.

Characterization of the Anisotropic Electrical Properties of Additively Manufactured Structures Made from Electrically Conductive Composites by Material Extrusion.

Additive manufacturing (AM) of components using material extrusion (MEX) offers the potential for the integration of functions through the use of multi-material design, such as sensors, actuators, energy storage, and electrical connections. However, there is a significant gap in the availability of electrical composite properties, which is essential for informed design of electrical functional structures in the product development process. This study addresses this gap by systematically evaluating the resistivity (DC, direct current) of 14 commercially available filaments as unprocessed filament feedstock, extruded fibers, and fabricated MEX-structures. The analysis of the MEX-structures considers the influence of anisotropic electrical properties induced by the selective material deposition inherent to MEX. The results demonstrate that composites containing fillers with a high aspect ratio, such as carbon nanotubes (CNT) and graphene, significantly enhance conductivity and improve the reproducibility of MEX structures. Notably, the extrusion of filaments into MEX structures generally leads to an increase in resistivity; however, composites with CNT or graphene exhibit less reduction in conductivity and lower variability compared to those containing only carbon black (CB) or graphite. These findings underscore the importance of filler selection and composition in optimizing the electrical performance of MEX structures.

Selective Void Deposition by Continuous, Ultrathin Ag Film Enabled Stable, High-Performance AgNWs-Based Transparent Heaters.

Metallic nanowire-based transparent conductors (MNTCs) are essential to various technologies, including displays, heat-regulating windows, and photo-communication. Hybrid configurations are primarily adopted to design stable, high-functioning MNTCs. Although hybrid MNTCs enhance electrical performance, they often suffer from optical degradation due to losses associated with the hybrid layers. Highly conductive hybrid MNTCs with minimal reduction in transparency are achieved with AgNWs/Ag(O)/Al-doped ZnO (AZO) design. The design provides a high visible light transmittance of 95.1%, representing a minimized optical loss of 3% compared to pristine AgNWs by optimizing optical interference between the AZO and Ag(O) layers. Furthermore, it allows for enhanced mobility of metallic nanowires by controlling the selective formation of conductive layers in the voids of the nanowire networks. The oxygen additive enables a continuous Ag ultrathin film of 6nm in the macro-voids of AgNWs system, corresponding to 25 times higher mobility for AgNWs/Ag(O)/AZO than that of sole AgNWs. The significant enhancement in the mobility of AgNWs/Ag(O)/AZO induces a reduction of sheet resistance of MNTCs by 73%. The AgNWs/Ag(O)/AZO, with an optimized sheet resistance of 24 Ω sq-1, is explored for transparent heater applications, demonstrating a fast thermal response with reliable stability, as evidenced by consistent high-temperature profiles during prolonged operation.

Compensation of phased array antenna electrical performance based on improved genetic algorithm

Phased array antennas are frequently subjected to surface distortions due to environ-mental factors during operation. Such distortions can lead to a deterioration in the electrical performance of the phased array antenna. This study provides an in-depth analysis of the impact of array distortions on electrical performance indicators. An electronic compensation approach, employing an enhanced genetic algorithm, is proposed to mitigate the effects of these distortions. The conventional genetic algorithm has been augmented with an elimination mechanism to boost convergence. This method compensates for amplitude and phase by calculating each element's amplitude and phase of the excitation current, thereby enhancing the convergence performance. Simulations this approach, simulations of rectangular microstrip patch antennas are conducted to validate the effectiveness of this approach. The simulation outcomes reveal that the proposed method significantly improves the antenna's radiation pattern and all performance indicators, confirming its efficacy.

The effect of Mn doping on the electrical and magnetic properties of Cr2Te3 thin films

Mn doped Cr2-xMnxTe3 thin films were prepared by molecular beam epitaxy technology. The effect of Mn doping concentration on the structural, morphological, electrical and magnetic performance of Cr2Te3 thin films were detailed analyzed. By varying the beam current of the Mn source, it is found that Mn can be doped into the Cr2Te3 thin film when the Mn source temperature is lower than 700 ℃, while the Mn tends to bind with Te as MnTe crystal for Mn source temperature higher than 700 ℃. Cr2-xMnxTe3 films all exhibt strong ferromagnetism with a Curie temperature of around 175 K. The magnetization of the films decreases with increasing Mn doping concentration. A notable negative magnetoresistance effect is observed with the highest MR ratio about −60 % in the vicinity of the Curie temperature. A clear topological Hall signal was observed in the sample with a Mn source temperature of 700 ℃ at low temperature (2 K). These results imply that the electrical and magnetic properties of Cr2Te3 materials can be effectively controlled by doping to meet the practical needs of different fields.

Si3N4-Assisted Densification Sintering of Na3Zr2Si2PO12 Ceramic Electrolyte toward Solid-State Sodium Metal Batteries

The solid-state metal battery with solid-state electrolytes has been considered the next generation of energy storage technology owing to its superior safety and high energy density. But, unfavorable ionic conductivity and interfacial problems make it difficult to widely use in practice. In this work, Si3N4 was rationally introduced into the NASICON matrix as a sintering aid, and the influence of Si3N4 on the crystal phase, microstructure, electrochemical and electrical performance of Na3Zr2Si2PO12 (NZSP) ceramic was systematically studied. The results demonstrate that the introduction of Si3N4 can effectively lower the densification sintering temperature of Na3Zr2Si2PO12 electrolyte and enhance the room temperature ionic conductivity of the NZSP to 3.82 × 10−4 S cm−1. In addition, since Si3N4 has a high thermal conductivity and can inhibit the transmission of electrons between the grains of the electrolyte matrix, it will effectively hinder the generation of sodium metal dendrites and relieve the concentration of the heat source. Moreover, owing to the desirable interface compatibility of the Na and NZSP-Si3N4 electrolyte, the Na/NZSP-1150-1%Si3N4/Na symmetric battery exhibits excellent stability, and the electrode/electrolyte interface still maintains good integrity even after long-term cycling. The assembled Na/NZSP-1150-1%Si3N4/Na3.5V0.5Mn0.5Fe0.5Ti0.5(PO4)3 cell manifests an initial specific capacity of 152.5 mA h g−1, together with an initial Coulombic efficiency of 99.8%. Furthermore, after 200 cycles, the battery displays a capacity retention rate of 82%.

Wired for stability: evaluating the electrical performance of a solution-processed zinc oxide-modified silver nanowire transparent electrode.

Silver nanowires (AgNWs) have gained much attention owing to their optoelectronic and mechanical properties and are therefore potential candidates to tackle intrinsic drawbacks of currently applied transparent electrodes in various (opto)electronic devices. In order for AgNWs to be justifiably considered as viable, it is necessary to address their insufficient stability by coupling them with another constituent into a nanocomposite. For this purpose, ZnO was chosen because of its low cost, solution processability and barrier properties. In this paper, a fully solution processed AgNW/ZnO TE film was investigated in order to understand the effect of ZnO coating on the electrical stability of AgNWs, including the mechanism of degradation during their exposure to high electrical current densities. The nanocomposite transparent electrode was processed with ZnO coatings to determine their effect on its optoelectronic properties and electrical stability, where the ZnO triple coated AgNW demonstrated the best combination of optoelectronic properties and stability at the highest working voltage.

Synthesis of perylene‐PEO hyperdispersants for aqueous graphene dispersion

AbstractGraphene, with excellent thermal conductivity, electrical and corrosion shielding performance has great application potential in the fields of heat dissipation coating, conductive agent and anticorrosion composite coatings. However, due to its large specific surface area, resulting strong aggregation behavior limits its application. Herein, the hyperdispersants with perylene anchoring groups are synthesized through the amidation coupling reaction between diacid anhydride and polyetheramine. The branching degree and length of hydrophilic chains on hyperdispersant are revealed to be the very important factors to affect the dispersion stability of aqueous graphene dispersion. The hyperdispersant with a single hydrophilic chain and the molecular weight 2000 of polyetheramine has the excellent dispersal activity discovered by Rheology, particle size distribution and Raman measurements. The possible mechanism is the strongest anchoring effect of perylene on graphene surface and thus achieving in best effective spatial exclusion stabilization effect of hydrophilic chains.

Improved Corona Resistance of Epoxy Resin for Gas‐Insulated Equipment in Nitrogen Gas by Direct Fluorination

Direct fluorination has demonstrated efficacy in modulating the surface electrical properties of epoxy insulators and preventing surface charge accumulation. Comparative corona treatments were conducted on both surface fluorinated (modified) epoxy samples and untreated (virgin/original) samples using a modified electrode setup in a nitrogen (N2) atmosphere. The purpose was to evaluate the resistance of the modified epoxy surface layer against corona discharge. The results of ATR‐IR analysis and SEM surface and cross‐sectional imaging indicate that corona treatment did not alter the chemical composition of the fluorinated sample or the thickness of the fluorinated layer. Based on assessments of potential decay and water contact angle measurements, the surface conductivity of the modified sample was decreased by corona treatment. The wettability of fluorinated sample remained unchanged after corona treatment, and no soluble degradation products were produced. Conversely, the surface conductivity of the virgin sample exhibited an increase following corona treatment, accompanied by the formation of soluble degradation products. These results confirm that direct fluorination improves the epoxy insulator's discharge resistance in N2 and provides technical support for enhancing the electrical performance of epoxy insulators in gas insulated equipment. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Liquid metal-enhanced composite conductive ink with improved electrical stability and durability for flexible electronics

For flexible electronics, conductive ink is a critical material with diverse applications. However, conventional inks, like those based on nano-silver, are expensive and result in printed patterns with limited conductivity stability. To address these limitations and enhance overall electrical performance, stability, and durability, this study developed a novel composite conductive ink incorporating liquid metal and silver microparticles. We fabricated conductive patterns and extensively investigated the sintering process, focusing on how liquid metal content and sintering techniques affect the resulting patterns' electrical performance and stability. Our findings reveal that incorporating liquid metal introduces a slight trade-off in the initial conductivity. However, subsequent thermal and hot-press sintering treatments significantly improve conductivity, with hot-press sintering leading to the most pronounced enhancement. Furthermore, the addition of liquid metal substantially bolsters the electrical stability of the patterns. Notably, conductive patterns fabricated using a 1:1 mass ratio of the ink exhibit ∆R/R0 values of only 1.72 and 0.432 after 5000 bending cycles, following thermal and hot-press sintering, respectively. This highlights the significant improvement in electrical stability and durability achieved by incorporating liquid metal into the conductive ink.

High-mass loaded redox-active lignin functionalized carbonized wood collector to construct sustainable and high-performance supercapacitors

Traditional electrode materials for supercapacitors often face issues like high toxicity, cost, and non-renewability. To address these drawbacks, biomass-based alternatives are being explored, aligning with green development trends. Herein, carbonized wood (CW) with rich pore structure and redox-active lignin are combined to fabricate an all-wood-based sustainable supercapacitor electrode material. Due to its inherent porous structure, CW provides a larger surface area for accommodating active materials ion, enabling the electrode to achieve a higher lignin loading capacity of 2.82–11.68 mg/cm2. Furthermore, the utilization of lignin as a substitute for conventional transition metal-based pseudocapacitor material functionalized CW endows the electrode with exemplary electrochemical performance while guaranteeing the comprehensive sustainability of the electrode. This synergy confers the electrode with exceptional electrical performance, yielding an areal capacitance of 960.7 mF/cm2 at a current density of 1 mA/cm2. The symmetric supercapacitors (SSC) manufactured by this composite electrode can achieve a notable areal energy density of 0.14 mWh/cm2 and a power density of 15.98 mW/cm2, while maintaining an outstanding capacitance retention rate of 81 % after 50,000 cycles at 20 mA/cm2. The manufacture of CW-lignin electrode underscores the potential of utilizing renewable biomass resources as alternatives for developing high-performance energy storage applications, thereby reducing negative environmental impacts.

Bending deformation effects on the optoelectronic performance of flexible GaInP/GaAs/InGaAs triple junction solar cells

To achieve genuine carbon neutrality, PV-powered vehicles show promise for future automotive development. However, the impact of curved surfaces on flexible solar cell module performance remains uncertain. This study specifically focuses on newly-designed flexible GaInP/GaAs/InGaAs triple junction solar cells, which have the highest potential output efficiency. A computational model was developed to analyze the electrical performance of curved solar cells, and variations in short-circuit current (Isc) and open-circuit voltage (Voc) with bending angles were determined to closely match experimental data. The effects of incident light intensity, angle, and bending strain on solar cell performance were analyzed to explain the observed Isc and Voc trends. This method can be applied to other III-V group solar cells, providing theoretical support for accurately calculating the performance of curved solar cell modules.

Fabrication and Performance Evaluation of a Directly Immersed Photovoltaic-Thermal Concentrator for Building Integration

A novel concentrating photovoltaic-thermal solar collector was designed, fabricated and experimentally investigated at the University of Lleida, in Spain. Two designs based on two dielectric liquids, isopropyl alcohol (IPA) and deionised water (DIW), were developed. In both cases, the solar cells were directly liquid-immersed. The study includes experiments and numerical simulations. The proposed concentrator was incorporated into a testing unit to examine its potential as a façade by controlling light and thermal flux transmitted into a building. The results show promising electrical performance and acceptable thermal performance, with thermal losses ranging from 14 to 20 W °C−1m−2. The optical efficiency was around 73% in the case of the concentrator with DIW and about 76% for the one with IPA. Regarding electrical performance, the fill factors for IPA and DIW configurations are as follows: 62.8% and 61.7%, respectively. The comparison results reveal striking differences between the testing unit with and without solar concentrators, with the concentrator-equipped unit showing around four times lower illuminance and a 50% reduction in maximum heat fluxes and interior temperature. Generally speaking, it can be said that these energy-generating façades show satisfactory behaviour and offer interesting possibilities for building-integrated applications.