Electrical Conductivity Characteristics Research Articles

A STUDY OF SPATIAL VARIABILITY IN A CHESTNUT ORCHARD (Castanea sativa) FOR PRECISION AGRICULTURE PURPOSES

The aim of this study is to study the variability of apparent electrical conductivity, quantity, and quality characteristics in a chestnut farm. The experiment took place in a chestnut orchard located in Agia, Larissa, Greece during the 2022 – 2023 growing season (April 2023 – October 2023), and specifically from the stage of tree dormancy to the stage of harvesting. All cultivation treatments were performed uniformly according to the farmer’s protocols. Soil data and chestnut samples were taken and evaluated to measure the above-mentioned variables (apparent electrical conductivity, quantity, and quality characteristics). The results showed that there was no significant correlation between apparent electrical conductivity and chestnut quality or quantity. They also showed obvious correlation between quantity and quality of chestnuts (high mass means plenty of chestnuts and vice versa).

Highly efficient Zn(O,S)/Mo(O,S)2 oxysulfide heterostructure photocatalyst for organic pollutant degradation

Environment and energy are presently some of the highest priority topics for mankind that need to be addressed. Organic pollutants are toxic and carcinogenic for human and aquatic life hence their presence in water even in low concentrations can cause serious health problems. Photodegradation of organic pollutants by utilizing oxide-based heterostructure photocatalysts is the promising approach to carry out remediation efficiently ascribed to the advanced optoelectronic and structural superiority of oxide photocatalysts. The Zn(O,S)/Mo(O,S)2 composites were synthesized via a facile solvothermal method at low temperatures. Several methods were used to characterize the composite morphology, structure, electrical conductivity, chemical composition, and optical characteristics. The heterostructured Zn(O,S)/Mo(O,S)2 oxysulfide was employed successfully in the photocatalytic degradation of organic pollutants. Among the as-prepared samples, the 30-ZnMoOS composite catalyst was found to have the highest photodegradation performance on various organic dye pollutants. The photocatalytic activity of the as-synthesized Zn(O,S)/Mo(O,S)2 samples was assessed on the photodegradation of different kinds of organic dyes under visible light irradiation. The photocatalytic degradation efficiency of 30-ZnMoOS composite over 10 ppm neutral red (NR), methylene blue (MB), rhodamine B (Rh B), and methyl orange (MO) was found to be 99.6 %, 99.9 %, 99.5 %, and 98.8 % within 40, 45, 180, and 180 min, respectively, under visible light illumination. In the present photocatalytic system, the superoxide (.O2-) anions, hydroxyl (.OH) radicals, and holes (h+) are proposed to be the direct reactive species causing the photodegradation of organic dyes.

Low temperature atomic layer deposition of PbO2 for electrochemical applications

A low temperature atomic layer deposition (ALD) process for PbO2was developed using bis(1-dimethylamino-2-methyl-2-propanolate)lead(II), Pb(DMAMP)2, and O3as the reactants, with a high growth rate of 2.6 Å/cycle. PbO2readily reduces under low oxygen partial pressures at moderate temperatures making it challenging to deposit ALD PbO2from Pb2+precursors. However, thin films deposited with this process showed small crystalline grains of α-PbO2and β-PbO2, without signs of reduced PbOxphases. The ALD PbO2thin films show the high electrical conductivity characteristic of bulk PbO2. In situ measurements of ALD PbO2film conductivity during growth suggest a reaction mechanism by which sub-surface oxygen mobility contributes to the growth of resistive PbO or PbOxduring the Pb(DMAMP)2surface reaction step, which is only fully oxidized from Pb2+to Pb4+during the O3reaction step. These films were electrochemically reduced to PbSO4in H2SO4and then reoxidized to PbO2, demonstrating their suitability for use as an electrode material for fundamental battery research and other electrochemical applications.

Electrical conduction and optical characteristics of Li2O and Bi2O3 Co-doped zinc-phosphate glassy nanocomposites: A critical observation of mixed ionic electronic effect

In the present report, the combined effects of the co-doping of metal oxide (Bi2O3) and Lithium oxide (Li2O) into the glassy matrix with chemical composition xLi2O-(0.45-x)Bi2O3-(0.15ZnO-0.40P2O5) (x = 0.05, 0.15, 025, and 0.35 mol%) are investigated thoroughly. The FESEM and X-ray diffraction data affirm the crystalline nature of the studied glassy composites. The obtained band gap energy values are declined from (3.68–3.17) eV, while the Urbach energy values are declined from (0.38–0.27) eV. Moreover, the mechanism responsible for AC conductivity has been analyzed using Almond–West formalism and Jonscher's universal power law. The observed rise in both AC and DC conductivity in the glass samples is attributed to the mixed ionic electronic effect. In the ionic diffusion model, an increased defect site concentration improves Li+ ion migration through percolation channels. The reduction in both electrostatic binding energy and strain energy lowers the Anderson-Stuart activation energy, facilitating Li+ ion migration and enhancing conductivity. Additionally, in the small polaron hopping model, an increase in the density of defect states suggests more defect sites that facilitate electronic hopping, creating deep localized states and transitions between localized and extended states. Replacing a Bismuth atom with a Lithium atom increases the number of non-bridging oxygen, enhancing the conduction band tail, reducing the energy needed for hopping conductivity, and increasing conductivity.

Electrically Conductive Lignin Reinforced Polyacrylic Acid/Hyaluronic Acid Scaffolds With PEDOT:HA Nanoparticles

ABSTRACTHydrogel materials are continually developing in biomedical engineering and recently a lot of effort has gone into their engineered performance in physiological applications. Porosity is an important characteristic for tissue engineering scaffolds to allow enhanced biocompatibility and the pore size needed is dependent on the application and type of tissue for which the hydrogel is being used to regenerate. Regarding biomedical applications, the use of conducting polymers is gaining in popularity due to their promising biocompatibility and potential to stimulate cell growth and proliferation through electrical stimulation. Building on previous hydrogel development by the authors, this study focuses on developing a biocompatible hydrogel scaffold with adjustable porosity and swelling capabilities, robust mechanical properties, electrical conductivity, and high thermal stability. The objective of this work is to examine the effect of freezing temperature, cross‐linker and porosity on the final characteristics of the scaffold and to then determine possible applications. The porosity, swelling degree, compression strength, biocompatibility, electrical conductivity, and thermal characteristics of the final material were analyzed and were found to be affected by the varied synthesis methods used. Overall, the synthesized scaffolds exhibit good biocompatibility with increased fluorescence over 3 days and over 70% cell viability, thermal stability up to 200°C and a range of swelling of 1725% to 8472%. They also portray robust mechanical properties with a Young's Moduli range of 11 kPa to 4.54 MPa and a porosity range of 0.78–71.98 μm depending on the synthesis methods used. Through variations in synthesis methods, highly porous, absorbent, and stable scaffolds have been synthesized. Notably, this single recipe is highly tailorable for use in a range of biomedical applications from tissue engineering to drug delivery and wound repair.

Cell Experiment Equipment by Using Ashes as Electrolytes

This article presents information about an experiment on how to create simple galvanic cell experiment equipment by using waste ash from burning as electrolytes, a copper plate as a cathode, and a zinc plate as an anode. The main purpose is to create a set of experimental equipment for teaching physics under the title of electrochemistry, to examine the possibility of generating electricity from ash, to study the change of the mixture ratio between the ashes and water that affects the open circuit voltage (OCV), to compare the value of the open circuit voltage from the sedimentation ashes electrolyte and non-sedimentation ashes electrolyte, and to study the pH value of the ash’s electrolyte within two hours. The research revealed that it can create five sets of galvanic cells by using different quantities of ashes, and it was found that the ashes from burning can generate electricity. The same type of ash with a different quantity will give almost the same OCV values, and changing the mixture ratio between ash and water will not affect the OCV values, which found that the mixing ratio between water and dry ash to become an electrolyte must use a minimum mixing ratio of water equal to ash or use a ratio of water more than ash to mix together. The results of measuring the value of OCV over a period of 2 hours found that the average value is almost constant, equal to 0.7 V. Here, we found that if the ash is allowed to settle, the value of OCV will decrease slightly, and if the ash is not allowed to settle, the value of OCV is constantly unchanged. It was also found that the pH value of the ash in each galvanic cell during the period of 2 hours was the same, with an average high alkalinity of about 13. This shows that alkaline electrolytes can generate electricity and have almost constant electricity. These five devices can be applied as a teaching tool for the Physics and Chemistry subject in the title of electrochemistry for students at the secondary school level and bachelor’s students because of an easy way to fabricate galvanic cells. The materials used are cheap and easy to find. It can also be used to study the characteristics of electrical conductivity in ash’s electrolyte and the characteristics of ash’s electrolyte.

Residues of Symbiont Cover Crops Improving Corn Growth and Soil-Dependent Health Parameters

Cover crops have emerged as a crucial tool in promoting sustainable agricultural practices, particularly in improving soil quality and soil–plant health. This study investigates the impact of single cover crop plants each with varying fungal and/or bacterial symbiosis capacities in a pot experiment. The growth of non-symbiont Ethiopian mustard (Brassica carinata), the associative bacterium symbiont black oat (Avena strigosa) and the double (fungus–bacterium) endosymbiont broad bean (Vicia faba) was studied on three distinct soil types, namely a less-fertile sandy soil (Arenosol), an average value of loam soil (Luvisol) and a more productive chernozem soil (Chernozem). Beside the biomass production, nitrogen content and frequency of AM fungi symbiosis (MYCO%) of cover crops, the main soil health characteristics of electrical conductivity (EC), labile carbon (POXC) and fluorescein diacetate enzyme activity (FDA) were assessed and evaluated by detailed statistical analysis. Among the used soil types, the greatest biomass production was found on Chernozem soil with the relatively highest soil organic matter (2.81%) content and productivity. Double symbiotic activity, assessed by soil nitrogen content and mycorrhiza frequency (MYCO%), were significantly improved on the lowest-quality Arenosols (SOM 1.16%). In that slightly humous sandy soil, MYCO% was enhanced by 45%, indicating that symbiosis was crucial for plant growth in the less-fertile soil investigated. After the initial cover crop phase, the accumulated biomass was incorporated into the Luvisol (SOM 1.64%) soil, followed by the cultivation of corn (Zea mays, DK 3972) as the main crop. The results indicate that incorporating cover crop residues enhanced labile carbon (POXC) by 20% and significantly increased the FDA microbial activity in the soil, which positively correlated with the nutrient availability and growth of the maize crop. This study emphasizes the importance of selecting suitable cover crops based on their symbiotic characteristics to improve soil quality and enhance soil–plant health in sustainable agricultural systems.

The Recent Advancement of Graphene-Based Cathode Material for Rechargeable Zinc–Air Batteries

Graphene-based materials (GBMs) are a prospective material of choice for rechargeable battery electrodes because of their unique set of qualities, which include tunable interlayer channels, high specific surface area, and strong electrical conductivity characteristics. The market for commercial rechargeable batteries is now dominated by lithium-ion batteries (LIBs). One of the primary factors impeding the development of new energy vehicles and large-scale energy storage applications is the safety of LIBs. Zinc-based rechargeable batteries have emerged as a viable substitute for rechargeable batteries due to their affordability, safety, and improved performance. This review article explores recent developments in the synthesis and advancement of GBMs for rechargeable zinc–air batteries (ZABs) and common graphene-based electrocatalyst types. An outlook on the difficulties and probable future paths of this extremely promising field of study is provided at the end.

Structural, optical and electrical conduction characteristics of PMMA/PVAc/TBAI blended polymers

This study aims to create tetra-n-butylammonium iodide (TBAI) doped poly(methyl methacrylate) (PMMA)/polyvinyl acetate (PVAc) blended polymers for utilize in a diversity of optoelectronic applications. By the casting technique, the films of (PMMA/PVAc/x wt % TBAI) were formed. The structure and morphology characteristics of the blended materials were studied using X-ray diffraction and scanning electron microscopy techniques. The optical transmittance declined to a minimum value when the blend was loaded with 38 wt % TBAI. The blend containing 38 % TBAI exhibits the highest reflectance values in the visible range. The lowest direct optical bandgap energies (4.20 eV) and indirect optical bandgap energies (3.71 eV, 3.13 eV) were achieved when TBAI reached 38 wt%. The addition of TBAI leads to an enhancement of the refractive index values of PMMA/PVAc in the visible spectrum. The effect of TBAI doping amount on the optical dielectric constant, energy loss functions, optical conductivity, nonlinear optical parameters and emitted color of the host blend was explored. The maximum values of the optical dielectric constant and energy loss functions were achieved after the TBAI level reached 38 wt%. The three non-linear optical (NLO) parameters for PMMA/PVAc blended polymers were enhanced as the amount of TBAI increased. An increase in voltage (V) or temperature results in a significant increase in electric current (I). Raising the amount of TBAI doping also caused the electric current to rise irregularly, with the exception of the blend with x = 11 %, where it fell. The samples exhibited the non-ohmic characteristics of the current-voltage (I–V) properties. The conduction mechanism of all blended materials was studied in detail. Finally, the outcomes supported the optical and electric properties studies, which suggested that a range of nanoelectronics applications could make use of the PMMA/PVAc/x weight percent TBAI blended polymers.

Innovative enhancements in polymer nanocomposites: Integrating ZnO nanorods into Hydroxypropyl methylcellulose/Polyvinyl pyrrolidone blend for advanced energy storage devices

Polymer nanocomposites are promising for various industrial and scientific applications due to their flexibility, diverse functionalities, and unique properties. In this study, zinc oxide nanorods (ZnO NRs) were incorporated into a blend of polymers (Hydroxypropyl methylcellulose - HPMC and Polyvinyl pyrrolidone - PVP) using a solution-casting technique, with concentrations varying from 2 % to 8 % by weight. Transmission electron microscopy (TEM) revealed that the ZnO NRs had an average diameter of 140 nm and a length of 3.22 μm. X-ray diffraction (XRD) analysis showed reduced crystallinity in the samples as the ZnO NR content increased. Fourier-transform infrared spectroscopy (FTIR) indicated changes in vibrational peaks due to interactions between functional groups in the blend and the nanorods. The addition of ZnO NRs significantly influenced the optical bandgap energies and UV/visible light absorption spectra of the samples. The bandgap of the nanocomposites significantly decreased upon ZnO NR incorporation, with direct and indirect bandgaps ranging from 5.19 to 4.70 eV and 4.74–3.66 eV, respectively. Electrical conductivity and dielectric characteristics were assessed across frequencies ranging from 0.1 to 10 MHz, revealing increasing AC conductivity, dielectric permittivity, and dielectric loss with higher ZnO NR content. Notably, at 10 Hz, the electrical conductivity increased from 3.5 × 10⁻12 S/m to 3.62 × 10⁻10 S/m upon loading with ZnO NR. The combination of adjustable optical bandgaps, frequency-dependent AC conductivity, and a wide range of tunable permittivity highlights the potential of these HPMC/PVP-ZnO NR nanocomposites for developing flexible optoelectronic and energy storage devices.

Structure-activity correlation for new phosphorylated quaternary ammonium salts: To antimicrobial activity via self-organization

The impact of the hydrocarbon tail length on the physicochemical properties of N-((diisopropoxyphosphoryl)methyl)-N,N-dimethyl-N-alkylammonium bromides (CnPN+Br-, where n = 10, 12, 14, 16, 18) was studied through surface tension, electrical conductivity, and spectral characteristics of hydrophobic probes (Orange OT, pyrene) measurements. In homologous series, the values of the critical micelle concentration (cmс) decrease and reach the micromolar range for hexadecyl and octadecyl derivatives. Surface tension isotherms were used to determine the maximum surface excess (Γmax), the minimum area per surfactant molecule at the air/water interface (Amin), and the Gibbs free energy of micelle formation (∆Gmic) and adsorption (∆Gad). Thermodynamic parameters (ΔGmic, ΔHmic, ΔSmic) and counterion binding degree values (β) were calculated from the temperature dependences of specific electrical conductivity on the CnPN+Br- concentration. It was established that micellization is a spontaneous and entropy-driven process. Additionally, aggregation numbers of CnPN+Br- were obtained from steady-state fluorescence quenching and dye solubilization techniques. It was established that the investigated cationic surfactants exhibit membranotropic activity against gram-positive bacteria Staphylococcus aureus, caused by depolarization of bacterial cytoplasmic membrane.

Hierarchical nanostructured Co0.5Mn0.5WO4 efficient electrode material for asymmetric supercapacitor application

BackgroundThis research focuses on the electrochemical characteristics of binary metal tungstates for asymmetric supercapacitor applications. Metal tungstates such as Cobalt tungstate (CoWO4) and Manganese tungstate (MnWO4) exhibit excellent electrical conductivity and redox characteristics. Different combinations of binary metal tungstates can serve as effective electrode materials for supercapacitor applications. MethodHerein, Co0.5Mn0.5WO4 nanoparticles was synthesized by the co-precipitation method followed by calcination. The prepared nanoparticles was used as an electrode material for the supercapacitor application. For study the two electrode system, Co0.5Mn0.5WO4 and activated carbon were worked as anode and cathode electrode, respectively. Significant findingsThe prepared electrode materials exhibit a battery type pusudocapacitance in cyclic voltammetry (CV). The charging and discharging properties of the material was analysed by galvanic charging and discharging (GCD) studies and it displays the specific capacitance value of 444 F/g at the current density of 1 A/g and it shows the specific capacitance retention of 91% after 1500 cycles. AC//Co0.5Mn0.5WO4 ASC device shows good energy density, power density and specific capacitance values of 30.5 Wh/Kg, 2800 W/Kg and 112 F/g at 1 A/g current density, respectively.

Investigation on ignition characteristics of charring conductive polymers stimulated by electric energy

The arc ignition based on charring conductive polymers has advantages of simple structure, low ignition power consumption and restart capacity, which bringing it broadly application prospect in hybrid propulsion system of micro/nano satellite. In order to optimize the performance of arc ignition system, it is essential to have a deeper understanding of the ignition processes and ignition characteristics of charring conductive polymers. In this paper, the thermal decomposition, electrical conductivity and thermal conductivity characteristics of charring conductive polymers with different conductive additives and matrix materials were comprehensively evaluated. An experimental investigation was conducted to determine the ignition behaviors and characteristics of different charring conductive polymers in a visual ignition combustor. The experiment result showed that the ignition delay and external energy required for ignition are negatively correlated with voltage and initial temperature of the ignition grain, but positively correlated with oxidizer flow velocity. Compared with charring conductive polymers containing multi-walled carbon nanotube, the ignition delay of charring conductive polymers with carbon black is significantly higher and the pyrolysis time is relatively longer. However, the ignition and initial flame propagation of charring conductive polymers with carbon black is more violent and more inclined to carbon particle ignition. Finally, the restart characteristic of different charring conductive polymers was studied. The ignition delay and external energy required for ignition of different charring conductive polymers all reduced with the increasing of the number of ignitions. However, the ignition characteristics would not change a lot after repeated ignition.

Excellent thermal conductive epoxy composites via adding UHMWPE fiber obtained by hot drawing method

AbstractThe continuous updating and iteration of electronic devices brings about a significant accumulation of heat. It is urgent to enhance the thermal properties of polymer‐based composites to alleviate the heat dissipation problem in the microelectronics industry. In this paper, the hot drawing process was introduced to increase the crystallinity of ultra‐high molecular weight polyethylene (UHMWPE) fiber and improve its thermal conductivity. The ultra‐high molecular weight polyethylene fiber/epoxy resin (UHMWPE fiber/Epoxy) composites with high thermal conductivity were prepared by compositing UHMWPE fiber with epoxy resin under vacuum conditions. Due to the good crystallinity of the UHMWPE fiber (86%), an efficient thermal conduction path is provided for phonons in the axial direction along the fibers. The results show that the thermal conductivity of the composites reaches a maximum of 3.51 W/mK (in‐plane), which is 17.47 times higher than that of the epoxy resin (0.19 W/mK). The thermography pictures indicate that the composites have better heat transfer capacity with an increase in the draw ratio (λ). In addition, the composites also have the characteristics of low density and low electrical conductivity. These researches will provide a new idea for the preparation of all‐polymer composites with high thermal properties.Highlights A hot drawing process was introduced to increase the crystallinity of UHMWPE fiber for improving thermal conductivity. High crystallinity facilitates the reduction of phonon scattering and the transmission of thermal energy by phonons. The obtained polymer composites exhibit an ultra‐high in‐plane thermal conductivity.

Modeling and Experiments on Temperature and Electrical Conductivity Characteristics in High-Temperature Heating of Carbide-Bonded Graphene Coating on Silicon.

A novel non-isothermal glass hot embossing system utilizes a silicon mold core coated with a three-dimensional carbide-bonded graphene (CBG) coating, which acts as a thin-film resistance heater. The temperature of the system significantly influences the electrical conductivity properties of silicon with a CBG coating. Through simulations and experiments, it has been established that the electrical conductivity of silicon with a CBG coating gradually increases at lower temperatures and rapidly rises as the temperature further increases. The CBG coating predominantly affects electrical conductivity until 400 °C, after which silicon becomes the dominant factor. Furthermore, the dimensions of CBG-coated silicon and the reduction of CBG coating also affect the rate and outcome of conductivity changes. These findings provide valuable insights for detecting CBG-coated silicon during the embossing process, improving efficiency, and predicting the mold core's service life, thus enhancing the accuracy of optical lens production.

Electrorheological and magnetorheological properties of liquid composites based on polypyrrole nanotubes/magnetite nanoparticles

This research presents an in-depth exploration of the electrical and magnetic properties of a polypyrrole nanotubes/magnetite nanoparticles (PPyM) material embedded in a silicone oil matrix. A key finding of our study is the dual nature of the composite, i.e. it exhibits a behaviour akin to both electro- and magnetorheological suspensions. This unique duality is evident in its response to varying electric and magnetic field intensities. Our study focuses on examining the electrical properties of the composite, including its dielectric permittivity and dielectric loss factor. Additionally, we conduct an extensive analysis of its rheological behavior, with a particular emphasis on how its viscosity changes in response to electromagnetic stimuli. This property notably underscores the material’s dual-responsive nature. Employing a custom experimental design, we integrate the composite into a passive electrical circuit element subjected to alternating electric fields. This methodological approach allows us to precisely measure the material’s response in terms of resistance, capacitance, and charge under different field conditions. Our findings reveal substantial changes in the material’s electrical conductivity and rheological characteristics, which are significantly influenced by the intensity of the applied fields. These results enhance the understanding of electro-magnetorheological properties of PPyM-based magnetic composites, and also highlight their potential in applications involving smart materials. The distinct electrical, magnetic and rheological modulation capabilities demonstrated by this composite render it as promising candidate for advanced applications. These include sensory technology, actuation systems, and energy storage solutions.

Nonlinear electrical conductivity characteristics under high impulse current and applications to lightning strike damage simulation for CFRP laminates

This experimental investigation assessed conductive properties of quasi-isotropic CFRP laminates in the thickness direction under high impulse current and clarified the properties’ effects on lightning damage behaviours. For CFRP laminates with interleaf resin layers (T800/3900-2B), experiments confirmed that conductivity in the thickness direction increases irreversibly with applied impulse current (approx. 5.3 kA, approx. 3.2 kV). However, the conductivity of CFRP laminates without interleaf resin layers (T800/2592) changed little during testing. Nonlinear conductive behaviour was applied to lightning strike damage numerical simulations using a coupled thermal–electrical analysis and heat transfer analysis. For numerical analyses, shape and dimensional changes of the applied current on the specimen surface were considered based on high-speed observations made during simulated lightning strike testing. The pyrolysis region calculated using damage analysis agrees well with experimentally obtained results when considering the potential gradient dependence of conductivity: better agreement was obtained than when calculated under a constant value.

Synergistic multi-functional N-doped carbon Nanocage@CNT/ZnMn2O4/Ti3C2 MXene: Powering battery, supercapacitor, and catalyzing hydrogen evolution

This study presents a novel approach to enhance the electrochemical capabilities of 3D pyrolytic carbon for energy applications. Using a chemical blowing technique, highly conductive carbon nanotubes (CNTs) are embedded within a 3D N-doped carbon nanocage (NCN). This integration involves an additional carbon source during Ni(NO3)2 induced polymer blowing, leveraging the dual role of Ni(NO3)2 in polymer expansion and catalyzing CNT growth. Our research merges ZnMnO4/Ti3C2 with high-capacity N-Doped Carbon Nanocage@CNT (NCN/CNT@ZnMnO4/Ti3C2) to amplify electrochemical performance. The NCN/CNT@ZnMnO4/Ti3C2 showed specific capacitance of 1843 Cg-1 at 1.0 Ag-1, attributed to augmented electrical conductivity and charge storage characteristics. The supercapattery configuration maintains a specific capacitance of 195 Cg-1 at 1.0 Ag-1, cyclic stability of 95% over 18,000 cycles, and a power density of 1145 W-kg−1 at an energy density of 67 Wh-kg−1. In HER applications, NCN/CNT@ZnMnO4/Ti3C2 demonstrates a lower Tafel slope of 56.41 mV-dec−1, signifying a significant advance in high-performance supercapacitors.

A comprehensive review on surface modifications of polymer‐based 3D‐printed structures: Metal coating prospects and challenges

AbstractThe production of complex structures out of a variety of materials has undergone a revolution due to the rapid development of additive manufacturing (AM) technology. Initially confined to applications such as magnetic actuators and two‐dimensional electric or electronic circuits, the convergence of 3D printing and metallization methods has emerged as a revolutionary approach. This synergy facilitates the creation of functional and customizable metal‐polymer hybrid structures characterized by high strength, lightweight properties, intricate geometric designs, and superior surface finish. These structures also exhibit enhanced electrical and thermal conductivity, as well as optical reflectivity. This paper reviews techniques to improve the effectiveness of 3D‐printed polymer antennas and structures by using various techniques of metallization. The metallization processes are examined, and a classification based on the materials employed is presented to facilitate comparisons that highlight the optimal utilization of materials for the fabrication of 3D‐printed polymer structures. The main emphasis here is on the effectiveness of different processes in terms of deposition, bonding strength, electrical conductivity, and various characteristics of metallic coatings developed on polymers. This review contributes an in‐depth analysis of the latest developments in 3D printing and metallization techniques specifically applied to polymer antennas and structures. The exploration extends to potential applications, challenges encountered, and future prospects within this dynamic field. As AM and metallization continue to evolve, this study aims to provide a comprehensive understanding of the state‐of‐the‐art methodologies and their implications for the future of polymer‐based structures and antennas.

PHYSICAL AND CHEMICAL PROPERTIES OF SUBSTRATE DERIVED FROM COFFEE RESIDUE FOR SEEDLING PRODUCTION

The physical-chemical properties of substrates based on coffee residues for seedling production were analyzed. The production of seedlings is associated with the quality of the substrates used. The characterization of the physical-chemical properties is a fundamental part of components and their proportions in formulating substrate selection. Thus, the objective of this work was to analyze the physical-chemical properties of components and formulations based on agro-industrial residues. The quality of the use of three components, fresh coffee straw, carbonized coffee straw, and composted coffee straw, in 25 different formulations of substrates for seedling production were evaluated. The dry density, current humidity, total porosity, aeration space, easily available water, water retention capacity, electrical conductivity, and pH were evaluated. The experiment followed a completely randomized design with three replications, and the data obtained were analyzed by ANOVA and the Scott-Knott test (p<0.05). All substrates had statistical differences among themselves, for all variables studied. Coffee processing residue presented physical and limited electrical conductivity and pH characteristics. Formulated products have physical and chemical characteristics depending on their constituents and proportions. Three substrates stood out for presenting good chemical and physical characteristics, which were based on 30-40% carbonized or composted coffee straw. The results obtained here will work as an important tool to guide decision-making regarding the constituents and adequate proportions in formulating substrates for seedling production