Electrical Conductivity Measurements Research Articles

Sustainable Utilization of Surfactant-Free Microemulsion Regulated by CO2 for Treating Oily Wastes: A Interpretation of the Response Mechanism.

Surfactant-free microemulsions (SFMEs) have been explored extensively to avoid the residual surfactant problem caused by traditional surfactant microemulsions. Many researchers focused on the SFMEs with tertiary amine, which exhibited the typical CO2 response behavior. In this study, the phase diagram of the SFMEs consisting of tripropylamine (TPA), ethanol, and water was readily prepared via the measurements of electrical conductivity. The CO2 response behavior of SFME was confirmed by determination of conductivity and measurement of the average diameter of SFME, which was mainly dependent on the protonation of TPA induced by the additional CO2. The transition of protonated TPA to a more hydrophilic nature from lipophilicity to hydrophilicity should be responsible for the variation of SFME average diameter. In addition, the SFMEs exhibited remarkable solubilizing capacity of crude oil, and three types of SFMEs achieved more than 80% oil removal rate in the washing process of oil sands. It was noted that both oil-in-water and bicontinuous SFMEs could be circularly utilized at least three times with a relatively high oil removal rate (%). Our work provided the insight perspective on the mechanism of SFMEs with a CO2 response behavior.

Activation of Ostwald ripening and electrical conductivity in polyHIPEs through the addition of ascorbic acid to graphene-stabilized emulsions

Ascorbic acid was employed to increase the sphere-to-sphere contact of polyHIPEs. Adding a radical inhibitor to the aqueous phase of a graphene-stabilized water-in-oil emulsion was hypothesized to delay the formation of a polymer skin around the dispersed droplet, leading to intimate contact between the surfactant-stabilized drops. Optical microscopy analysis of samples made with varying ascorbic acid concentrations showed decreased sphere size and increased size dispersity at increasing inhibitor concentrations. Electrical conductivity measurements showed an increase at low concentrations of ascorbic acid but a decrease in conductivity at higher concentrations. Our results suggest that the presence of an inhibitor does delay the formation of the polymer skin and allows more intimate contact between spheres, but at higher concentrations, it leads to Ostwald ripening. Scanning electron microscopy of polystyrene/graphene composites revealed that the inhibitor also stopped the polymerization of aqueous-dispersed monomer, leading to polymer patches on the interior of the spheres.

Measurement of electrical conductivity of transformer oil based nanofluid

In this article, an attempt was made to evaluate the electrical conductivity of ananofluid based on transformer oil. For this purpose, several nanofluid samples with different concentrations of dielectric silicon dioxide nanoparticles and conductive zinc nanoparticles were prepared. The dielectric permittivity and electrical conductivity of the obtained nanofluids were measured experimentally. After processing the experimental results, a theoretical calculation was made using the Nielsen formula. After the calculation, the results were compared with the experimental data. In the process of comparative analysis, the correspondence of the calculated and experimental values of the dielectric permittivity was noted. There was also a discrepancy between the experimental and calculated values of electrical conductivity. An explanation is proposed for the discovered discrepancy between the calculated and experimental values. Presumably, the main reason for the decrease in electrical conductivity in the experiment is the adsorption of ion particles in the dielectric.

Novel flavonoid derivatives containing 1,2,4-triazolo[4,3-a]pyridine as potential antifungal agents: Design, synthesis, and biological evaluation

A series of flavonoid derivatives containing 1,2,4-triazolo[4,3-a]pyridine were designed, synthesized and evaluated for their antifungal activity. Bioactivity tests showed that some target compounds exhibited the strong antifungal activity against Botrytis cinerea (B. cinerea), Sclerotinia sclerotiorum (S. sclerotiorum), and Phomopsis sp. Among them, the half maximal effective concentration (EC50) value of S2 against B. cinerea was 3.3 μg/mL, which was less than that of the control drug azoxystrobin (21.0 μg/mL). The EC50 value of S2 against S. sclerotiorum was 12.7 μg/mL, which was better than that of azoxystrobin (28.1 μg/mL). In addition, the in vivo protective and curative activities of S2 against blueberry were 92.0 and 79.8 % at 200 μg/mL, respectively, which were higher than those of the control drug azoxystrobin (89.4 and 71.7 %). Scanning electron microscopy (SEM) and spore germination experiments showed that S2 could not only cause the mycelium damage but also inhibited the spore germination. Fluorescence microscopy (FM) observation, relative electrical conductivity measurement and cytoplasmic leakage assays indicated that S2 could affect cell membrane integrity by inducing lipid peroxidation and increasing cell membrane permeability as well as causing leakage of cytoplasmic contents. These results show that flavonoid derivatives containing 1,2,4-triazolo[4,3-a]pyridine had excellent inhibitory effects on B. cinerea, providing another supplement for the development of new pesticides.

Electrical Conductivity Measurements of the Binary NaCl-CaCl2, the Ternary NaCl-CaCl2-BaCl2 and the Quaternary NaCl-CaCl2-BaCl2-ZnCl2 Molten Salts

An emerging set of batteries, called the molten salts or all liquid battery, are designed for cheap energy storage and electrical grid buffering purposes (1). Some molten salt batteries are commercial or close to commercial like the ZEBRA, NaS and Ambri batteries, however, most of these battery technologies are still on an experimental, lower TRL level but can become increasingly important in the future as the shift towards more intermittent energy sources emerge and as the development of these batteries become more mature. One suggested battery technology is the Na-Zn battery (2). This battery technology is currently further investigated in the EU funded SOLSTICE project (Grant Agreement No 963599). The Na-Zn battery will have Na and Zn electrodes and the electrolyte – the molten salt – will be a NaCl-CaCl2 based electrolyte, with additions of BaCl2 or perhaps even BaCl2 and SrCl2. The NaCl content of the electrolyte gives the charge of the battery, CaCl2 lowers the operating temperature and BaCl2 and SrCl2 increases the density of the electrolyte. The operating temperature of the battery is approximately 600 °C and joule heat generated inside battery during charging and discharging due to resistance of the electrolyte allows to maintain this operating temperature. The composition of electrolyte changes with the battery state of charge hence the internal resistance of battery is not constant during normal operation. Therefore, precise data of electrical conductivity of the electrolyte is required for modelling its performance thermal balance.A method for measuring electrical conductivity has been built in the SINTEF laboratory. The setup used for the measurements is presented in Figure 1a. It consists of two tungsten electrodes immersed in molten electrolyte – one electrode is stationary and the other is moving inside a capillary. Position of the moving electrode inside the capillary is precisely controlled by a height gauge. Shielded thermocouple is used for measuring temperature. To avoid polarization of electrodes during measurement, electrical impedance spectroscopy (EIS) at open circuit potential is used. The principle of the method is that resistance between the electrodes is measured at different positions of the moving electrode inside the capillary. Measured resistance can be expressed by the following formula: R=R0+ρ·(l/A) Where R0 is the offset resistance of electrolyte outside capillary including resistance of electrodes and leads,ρ is the resistivity of electrolyte, l is the length between end of capillary and tip of the moving electrode, A is the area of the capillary. The measurement of resistance is repeated at different positions of the moving electrode relative to the chosen reference position. Since R0 and A are constant, resistivity can be calculated knowing only the tangent of function R = f(l) (Figure 1b) divided by A. The presented approach is characterized by high precision and robustness due to no requirement of cell constant values, which is problematic to estimate at high temperature. It is only based on relative movement of one electrode which is easy to control. In addition, a higher number of positions of the moving electrode at which the measurement is performed effectively helps to eliminate errors. Conductivity is the inverse resistivity. Electrical conductivity measurements were done at a range of temperatures, from 600 °C to 800 °C with 50 °C steps and the results are presented in the form of linear formulas intended for use in User Defined Functions in modelling.Conductivity of various chloride salt compositions containing NaCl, CaCl2, BaCl2 and ZnCl2 have been investigated using the presented technique. It is generally found that the electrical conductivity is almost linear with temperature increase in the range of liquidus temperature up to approximately 800 °C for the investigated electrolyte compositions. Above that region the relationship is not linear anymore. This region is not presented in this presentation. It is also found that the conductivity increases with increasing NaCl content and that larger cations like Ca and Ba reduce the conductivity of the molten salt. The method has proven very powerful to measure electrical conductivity on molten salts and the results are comparable to experimental results found in literature (3).

The Relevance of Carbon for Energy Transition: Ways to Assess Its Surface Properties and Standardize Their Characterization

Technical carbon blacks (CB) are well-established materials that gain increasing attraction in the context of electrification and transition towards renewable energy sources. Their availability, low price, and favorable properties (e.g., conductivity, specific surface area) make them ideal candidates as additives in batteries or as support material for electrocatalysts, e.g., in fuel cells [1]. However, due to the vast number of producers and manufacturing processes large variations in their properties can be observed making product quality control difficult.To this end, we report on ways and methods to standardize the characterization of CB materials that are specifically designed for fuel cell and battery applications. By applying analytical centrifugation (AC) and combining it with complementary methods (e.g., electrical conductivity measurements, Boehm titration), we identify parameters like particle size, morphology, and surface properties that are influential for the overall value chain in electrode manufacturing. This helps to minimize the effects of material inherent property fluctuations as well as process-related fluctuations on the final electrochemical performance.Four different CBs were investigated, and their various properties were assessed. Our results show that the degree of graphitization and hence the electrical conductivity in a CB can be correlated with the overall surface basicity. Moreover, these properties can be linked with their dispersibility features on the ink formulation level and studied via liquid phase characterization using Hansen Parameters (Fig. 1) [2]. In brief, the higher the basicity of a CB surface is, the better the interaction with non-polar/mildly polar aprotic solvents becomes. This is especially true when oxygen-containing surface functional groups that cause a higher overall polarity of the material are missing.Figure 1: Hansen interaction space (for polar, disperse and hydrogen bonding interactions) showing the location of various solvents that are used as probe liquids for determining the Hansen Similarity Parameters of the respective CBs in 3D space (a) and 2D representations (b-d).To conclude, we were able to identify differences in CB materials by applying AC-based characterization techniques. Those differences can have a huge impact on the overall process chain of electrode production as they are decisive not only in formulation considerations but also in the subsequent processing steps. In the future, we will focus on closing the process chain and try to apply our characterization routines for an efficient identification of decisive process parameters at every stage of production. Additionally, we want to transfer knowledge gained from lab-scale techniques (e.g., sonication methods) to industrially relevant mixing procedures. By this, we will give electrode manufacturers tools at hand for a fast characterization of feed materials to save costly and lengthy adjustments of processes due to quality fluctuations. An accelerated implementation of green energy solutions is sought by this approach.

Hollow TiO2 Supports for Enhanced Acidic Oxygen Evolution Activity

The usage of scarce and expensive iridium as a catalyst for the acidic oxygen evolution reaction (OER) represents a significant barrier to up-scaling the deployment of proton exchange membrane water electrolysers (PEM-WEs). Accordingly, strategies such as nanostructuring catalysts to increase the electrochemical surface area (e.g. nanoparticles, single-atom catalysts, nanoclusters) as well as investigating mixed metal alloys and oxides (e.g. perovskites, pyrochlores) have been developed with promising half-cell performances. One further approach that has recently gained attention is the deployment of catalyst-supports whereby a high surface area support is used to scaffold the dispersed iridium catalyst.1 Analogous to the selection of a catalyst, the catalyst support must withstand the highly corrosive and oxidising conditions of a PEM-WE anode. Thus, metal oxides such as titanium dioxide are commonly deployed as catalyst-supports for acidic OER. The catalyst-support moiety must also be sufficiently conductive when integrated into the PEM-WE catalyst layers. Otherwise, the cell voltages required to generate sufficient activity will render the device impractical. Accordingly, strategies such as doping, or the addition of conductive layers between the catalyst and support have been investigated.2 In this study we investigate a unique support morphology that affords promising OER activity and stability in acidic electrolyte with high iridium mass activities. Specifically, we deploy a hollow TiO2 catalyst support,3 coated with a Au/Pd interlayer to provide electrical conductivity. The OER activity and stability is initially screened in a rotating disk electrode (RDE) configuration as a function of thermal treatments (reducing vs oxidising) as well as with at various Au/Pd (1 – 5 wt%) and Ir loadings (35 – 50 wt%). Our highest performing catalyst have a mass activity of around 480 A/gIr at 1.60 V vs RHE. The catalysts are subsequently investigated in a membrane electrode assembly (MEA) and subject to 10k accelerated stress test stability measurements. To understand the role of the support morphology, Au/Pd interlayer and iridium loadings on electrochemical performance, we also characterise the synthesised catalysts by (scanning) transmission electron microscopy (STEM/TEM), X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS) and electrical conductivity measurements. Collectively, we report the critical role of the Au/Pd interlayer to enable such high electrochemical performance. We also show that the hollow structure of the TiO2 support may be enhancing mass transport in the catalyst layers. References 1 A. S. Pushkarev, I. V Pushkareva and D. G. Bessarabov, Energy & Fuels, 2022, 36, 6631–6625.2 Y. N. Regmi, E. Tzanetopoulos, G. Zeng, X. Peng, D. I. Kushner, T. A. Kistler, L. A. King and N. Danilovic, ACS Catal., 2020, 10, 13125–13135.3 U. S. Jonnalagadda, X. Su and J. J. Kwan, Ultrason. Sonochem., 2021, 73, 105530.

Structural and dielectric properties of lead-free Ba0.9Ce0.033Ca0.05TiO3 perovskite ceramic

This work is devoted to the synthesis, the structural study, mainly by X-ray diffraction, and to the investigation of the electrical and dielectric properties of solid solution Ba0.9Ce0.033Ca0.05TiO3. This compound was synthesized, by the solid route, in the form of powder and massive ceramic. We have performed dielectric and electrical conductivity measurements which demonstrate the ferroelectric nature of this compound. The X-ray diffraction study established the existence, at room temperature, of a perovskite phase with tetragonal symmetry. Dielectric relaxation time (τ) was adjusted by Arrhenius law with the activation energy of 42.5 meV.

Ni and Fe Doped (La,Sr)TiO3 Fuel Electrodes for Solid Oxide Cells – Electrical and Electrochemical Properties

Development of robust and impurity tolerant solid oxide cells (SOCs) has attracted a significant R&D-effort in recent years. The shortcomings of Ni-YSZ fuel electrodes in terms of redox stability, carbon and sulfur tolerance and long-term durability under strong polarization has spurred the search for alternative fuel electrode materials. Among them, doped strontium titanate materials has shown promising performance due to their good electrical transport properties, chemical and redox stability and tolerance towards impurities.In the present study, the electrical properties of the La0.477Sr0.33Ni0.03Fe0.03Ti0.94O3- δ (LSFNT) material, which is designed with the potential for exsoluting Ni and Fe nanoparticles, is investigated in detail. In addition, the performance of LSFNT based fuel electrodes is characterized in a symmetrical cell configuration. The electrical conductivity measurements are performed on both dense and porous LSFNT layers, as a function of temperature and pO2. The pre-reduced (1100oC, 24 hours, dry 5%H2/N2) dense LSFNT sample showed an electrical conductivity of ca. 10 S/cm at 850 oC in dry 5%H2/N2. The “in-situ reduced” (850oC, 700 hours) porous LSFNT layer showed a conductivity 10 times smaller. The conductivity was tracked as a function of pO2 showing an approximate pO2 -1/6 dependence. Also the ionic conductivity of the material was determined using an electron blocking method. At 850oC at a pO2 of 10-20 bar the ionic conductivity is ca. 0.05 S/cm at which is similar to that of Y2O3 doped ZrO2 electrolytes demonstrating that LSFNT is indeed a very good mixed ion- and electron-conducting material.Motivated by the observed conductivities SOC fuel electrodes of LSFNT were prepared by incorporating Gd-doped CeO2 electrocatalyst into LSFNT porous backbones and their electrochemical performance was measured in 50% H2 / 50% H2O at OCV. An electrode polarization resistance of 0.05 Ω cm2 at 850oC and 0.26 Ω cm2 at 650 oC is measured for these electrodes. The polarization resistance at 850 oC is comparable to that of Ni-YSZ fuel electrodes; while at 650oC it is significantly lower in similar atmospheres. This promising electrochemical performance shows the potential of the LSFNT fuel electrodes, as an alternative to Ni-YSZ fuel electrodes, in solid oxide cell applications.

(Invited) Processing of Perovskite Materials for Optoelectronic Devices

Among materials used for thin film technologies, perovskite materials have emerged as one of the rising stars for optoelectronic applications. They show great promise for several applications like e.g. photovoltaics, lasers, light emitting diodes or X-ray detectors. Their success is founded on the feature of some perovskite materials to be largely tolerant to the formation of defects, which enables functional layer deposition from liquid precursor inks. In order to exploit the extraordinary optoelectronic properties, it is necessary to adapt the material processing to the requirements of the application. For a large spectrum of devices, homogeneous, high quality, large grain poly-crystalline perovskite layers are required. Accordingly, our work strives to cover the whole spectrum of the layer formation ranging from the perovskite precursor ink chemistry, the deposition process to post-processing and re-crystallization.Regarding the precursor ink, we spotlight the complex formation of the lead halide species by nuclear magnetic resonance and electrical conductivity measurements. We found a strong and systematic impact of the choice of (Lewis base) solvent on the formation of lead complexes in the precursor solution. Surprisingly, a strong difference in the complex formation, not necessarily translates to notable differences in the resulting layers. Indeed, the difference observed in solvation and coordination appears to become less for increased concentrations of the precursor ink. As such we assume, that throughout the drying process, the impact of lead-solvent complexes observed in the ink might diminish. To add another parameter, we also included Lewis-base additives into our investigations, that evidently modify the shape and size of the crystallites in the resulting layers. Despite their far higher donor number, we found the additive to only marginally impact on the lead core in the liquid precursor. Rather, by in-situ GIWAXS characterization, we could show that the intake of thermal energy during the annealing process proves crutial for changes in the crystal formation. After a gas-quenching process, where the perovskite phase is already present, the formation process with and without additive did not show notable differences. Subsequent thermal annealing of the deposited layers on the other hand allows the coordination between lead and the additive and affords a re-organization of the perovskite phase. During the deposition process, anyhow, the process technology (like gas quenching) is still important to form a homogeneous and pinhole-free initial film, which then can reorganize to form a high-quality perovskite layer.In the second part of the presentation, we will show, that the strategy of thermally assisted reorganization is not limited to the initial annealing step. By using a thermal hot-pressing process, we are also able to trigger the perovskite re-organization and re-crystallization even if the perovskite deposition and formation process is already finished. We performed post-processing by providing thermal energy, while simultaneously limiting the available space where potential perovskite decomposition products could leak, by pressing it with a flat stamp. As a result, the perovskite recrystallizes and forms extremely smooth layers that comprise large grains and express remarkable optical quality. We show this strategy to be applicable to a large variety of different hybrid as well as all-inorganic perovskite materials. Employing patterned stamps, we also utilize this strategy to directly imprint photonic nanostructures (e.g. Bragg gratings) into the perovskite layers.We will show how additive driven reorganization and thermal imprint enable a variety of optoelectronic devices ranging from light harvesting (single-junction and tandem perovskite based solar cells) to stimulated light emission (perovskite lasers).

Molecular interactions of cationic/anionic surfactants in presence of anionic antibiotic drug cloxacillin sodium at different temperatures: Micellization and thermodynamic studies

The physicochemical properties and interactions of surfactant–drug aggregates are regarded as essential features to achieve optimum therapeutic action of the drug. In this article, the effect of various concentrations of anionic antibiotic drug cloxacillin sodium (ClxNa) on the micellization of cationic surfactants such as cetyltrimethylammonium bromide (CTAB), tetradecyltrimethylammonium bromide (TTAB) and anionic surfactant sodium dodecyl sulphate (SDS) have been investigated using electrical conductance measurement at different temperatures (288.15 K, 293.15 K, 298.15 K, 303.15 K, 308.15 K, and 313.15 K). The results suggest an increase in critical micelles concentration (CMC) values for cationic surfactants (CTAB/TTAB) with a rise in drug concentration (0 mM up to 10 mM) whereas anionic surfactant SDS shows a decrease in CMC at higher drug concentrations (from 2.5 mM up to 10 mM) at all the studied temperatures. The degree of counterion dissociation (α) values for TTAB aggregates show a slight increase with [ClxNa], except at a few lower temperature ranges whereas such a regular trend was not obtained for CTAB and SDS aggregates. Temperature-dependent CMC values show a nonlinear nature with a rise in temperatures and follow a U-shaped curve for all studied pure surfactant and surfactant–ClxNa systems. Micellization for all surfactant-drug systems is found to be spontaneous. Investigation of other temperature-dependent thermodynamic parameters such as change in standard enthalpy (ΔHm0), and entropy (ΔSm0) of micellization suggest that surfactant–drug interactions are both endothermic (ΔHm0 < 0, particularly at lower temperatures) and exothermic (ΔHm0 < 0, at higher temperatures), whereas micellization is largely entropically driven (ΔSm0 > ΔHm0).

CONTAMINAÇÃO POR NITRATO EM ÁGUAS DE POÇOS RASOS DESTINADAS AO CONSUMO HUMANO EM ICOARACI, MUNICÍPIO DE BELÉM, ESTADO DO PARÁ

The research aims to assess the water quality of shallow wells utilized by the local inhabitants of the Parque Guajará neighborhood, located in the Icoaraci District of Belém Municipality, State of Pará. This assessment was conducted in accordance with the criteria delineated by Ordinance GM/MS nº 888, an edict established by the Ministry of Health. In the year 2016, a series of samples were collected from 15 specifically chosen shallow wells. This sampling was arranged to align with the distinct climatic patterns of the region, spanning the rainy season (January and May) and the drier period (August and October). The investigation analyzed the following parameters: pH, electrical conductivity, nitrite, ammonium, and nitrate content. During the time of the sample collection phase, recorded pH values oscillated between 3.93 and 6.42, while the measurements of electrical conductivity exhibited a peak at 527 µS/cm. Notably, ammonium concentrations peaked during the rainy season at 6.01 mg/L, whereas nitrite levels reached their peak during the less rainy season at 0.44 mg/L. High nitrate levels were particularly observed, predominantly during the rainy season, increasing up to 64.03 mg/L. Signs of a nitrification process could be seen within the samples from two wells under investigation. Statistical analysis highlighted positive correlations between electrical conductivity and nitrate levels, as well as between pH and ammonium concentrations. Based on these data, it became evident that nitrate contamination was pervasive in the residual groundwater of the shallow wells. This nitrate contamination, a fundamental concern throughout the sampling period, under scored the significant influence of septic tank systems on the analyzed water. This contamination, in turn, threatens the well-being of the people who depend on these water sources for consumption, thereby requiring urgent attention.

Compensation of the material temperature influence on specific electrical conductivity during eddy current structurescopy

The importance of eddy current measurements of specific electrical conductivity (SEC) of materials in non-destructive testing for solving problems of structuroscopy is discussed. In particular, their significant role is shown for estimation of the degree of changes in the mechanical characteristics of structural materials due to degradation processes in their structure. The influence of the temperature of metallic structural materials on the results of eddy current measuring of SEC has been studied. An analytical expression for the output signal of the SEC measuring channel of an electrical eddy current conductivity meter for real temperature of material is obtained. It depends on the value of the material SEC at a nominal temperature value (usually 20 C), temperature coefficient of electrical resistance of the material and the deviation of the material real temperature from the nominal value. It is shown that in order to tune out this effect and bring the measurement results to the nominal temperature, it is necessary to use eddy current meters with an additional channel for measuring the material temperature in the testing zone. The output signal of this channel is used to correct the SEC measurement results. This is carried out by multiplying the output signal of the SEC measurement channel and some auxiliary signal. This auxiliary signal is generated from the output signal of the temperature measurement channel by it scaling and summation with the signal of the direct current voltage reference source. A functional diagram of the eddy current SEC meter with temperature correction is proposed. A detailed description of it operation is given. In the absence of preliminary information about the grade of material and the value of its temperature coefficient of electrical resistance, is proposed to suppress the influence of temperature by test changes in the temperature of the material in the testing zone. At the same time, it is necessary to adjust the gain of the scale converter. This is done until the readings of the eddy current SEC meter do not depend on the material temperature in the testing zone.

Fe dopant controlled the ferromagnetic, structural, thermal, optical, and electrical characteristics of CdO nanoparticles

This research paper presents a study on (Fe) doped CdO nanoparticles focusing on their structural (XRD), thermal (TGA and DTA), optical (UV–vis), magnetic (VSM and ESR), and electrical characteristics. The synthesis of Cd1-xFexO with (x = 0.0, 0.01, 0.05, 0.10, 0.15, and 0.20) nanoparticles was carried out using the co– precipitation technique. Fe dopants showed a great impact on the structural parameters and the thermal stabilities of obtained nanomaterials. SEM and TEM imaging techniques are employed to investigate the morphology, size, and distribution of the Cd1-xFexO nanoparticles. UV spectroscopy was employed to better understand the electronic transitions and optical characteristics. Furthermore, magnetization measurements from ESR and VSM showed a weak ferromagnetic order with a high Fe concentration. For instance, the Ac electrical conductivity measurements were used to determine the electrical properties, dielectric losses, and charge transport mechanisms between the Fe-dopants and CdO. The structural, thermal, optical, magnetic, and electrical characteristics data are complemented to better understand for Cd1-xFexO materials for employing them in magnetic storage and sensors, photocatalysis, other future applications.

Improving a regional peat thickness map using soil apparent electrical conductivity measurements at the field-scale

IntroductionThe increased adoption of proximal sensors has helped to generate peat mapping products: they gather data quickly and can detect the peat-mineral later boundary. A third layer, made of sedimentary peat (limnic layers, gyttja), can sometimes be found in between them. This material is highly variable spatially and is associated with degraded soil properties when located near the surface.MethodsThis study aimed to assess the potential of direct current resistivity measurements to predict the maximum peat thickness (MPT), defined as the non-limnic peat thickness, to facilitate soil conservation and management practices at the field-scale. The results were also compared to a regional map of the MPT from a previous study used and also tested as a covariate. This study was conducted in a shallow (MPT = 8-138 cm) cultivated organic soil from Québec, Canada. The MPT was mapped using the apparent electrical conductivity (ECa) from a Veris Q2800, and a digital elevation model, with and without a regional MPT map (RM) as a covariate to downscale it. Three machine-learning algorithms (Cubist, Random Forest, and Support Vector Regression) were compared to ordinary kriging (OK), multiple linear regression, and multiple linear regression kriging (MLRK) models.Results and discussionThe best predictive performance was achieved with OK (Lin’s CCC = 0.89, RMSE = 13.75 cm), followed by MLRK-RM (CCC = 0.85, RMSE = 15.7 cm). All models were more accurate than the RM (CCC = 0.65, RMSE = 29.85 cm), although they underpredicted MPT &amp;gt; 100 cm. Moreover, the addition of the RM as a covariate led to a lower prediction error and higher accuracy for all models. Overall, a field-scale approach could better support precision soil conservation interventions by generating more accurate management zones. Future studies should test multi-sensor fusion and other geophysical sensors to further improve the model performance and detect deeper boundaries.

Dopant induced band convergence leading to high thermoelectric power factor in Mg2Sn

Band convergence is a common technique for enhancing the power factor of thermoelectric (TE) materials. This is usually achieved by solid solution formation in compounds having specific electronic band features. In this work, we show that a similar band convergence effect can be achieved in Mg2Sn by doping with small amounts of Bi. To identify this effect and the possible reason behind it, a detailed investigation of the electronic band structure (EBS) has been carried out using a recently developed multi-band refinement technique (MBRT). Nominal compositions of Mg2.2Sn1-xBix (x = 0,0.005, 0.01, 0.0125, 0.015, 0.02) have been synthesized by induction melting followed by compaction using uniaxial hot-pressing. Measurement of Seebeck coefficient (S), electrical conductivity (σ) and Hall Coefficient (RH) have been performed between 300K–700K and the data used for multi-band refinement. Results indicate changes in the inter-band separation of conduction bands with doping content and temperature. Significantly lower inter-band separation compared to reported undoped data is found even for the lowest doped composition, resulting in both conduction bands contributing to the power factor (S2σ). Further, for the heavily doped compositions (x = 0.0125, 0.015, 0.02) band-flipping between the conduction bands has been observed. Thus, the light conduction band is found to constitute the conduction band edge in the heavily doped compositions. This is contrary to the reported EBS of undoped Mg2Sn in which the heavy conduction band has a lower energy. Also, increasing temperature results in band convergence in the heavily doped compositions. A plausible cause for the band-flipping behaviour is provided based on merging of the impurity band with the light conduction band in heavily doped Mg2Sn. The band-flipping and the subsequent band convergence results in an even higher S2σ in the heavily doped compositions. The work highlights the beneficial influence of Bi doping on the TE properties of Mg2Sn and opens the possibility of utilizing dopants for achieving band convergence in TE materials.

Comparative structure, optical and electrical characteristics of sol-gel-deposited In-, Ga-, and Sn-doped CuO thin films

Doping of metal-oxide thin films provides an effective method to improve the performance of various devices based on them such as solar cells, photodetectors, and gas sensors. Developing high-performance of these devices, the influence of In, Ga, and Sn dopants on structure, optical and electrical characteristics of CuO deserves further study. Herein, undoped and In-, Ga-, and Sn-doped CuO thin films are deposited on glass substrates by the sol-gel method, and the parameters influenced by these dopants are determined systematically. The effect of studied dopants on XRD, SEM, UV-vis, PL, and electrical conductivity measurements are examined, and the results are correlated with each other. Additionally, the electrical transport mechanism of the films is comprehensively investigated. It is determined that the multi-phonon hopping (MPH) conduction mechanism governs the temperature-dependent conductivity of the films. Finally, it is found that the probed dopants significantly impact the properties of CuO thin film.

Novel venous balloon for compliance measurement and stent sizing in a post-thrombotic swine model

Objective: Real-time accurate venous lesion characterization is needed during endovenous interventions for stent deployment. The goal of this study is to validate a novel device for venoplasty sizing and compliance measurements.Methods: A compliance measuring sizing balloon (CMSB) uses real-time electrical conductance measurements based on Ohm’s Law to measure the venous size and compliance in conjunction with pressure measurement. The sizing accuracy and repeatability of the CMSB system were performed with phantoms on the bench and in a swine model with an induced post thrombotic (PT) stenosis in the common femoral vein of swine.Results: The accuracy and repeatability of the CMSB system were validated with phantom bench studies of known dimensions in the range of venous diameters. In 9 swine (6 experimental and 3 control animals), the luminal cross-sectional areas (CSA) increased heterogeneously along the PT stenosis when the CMSB system was inflated by stepwise pressures. The PT stenosis showed lower compliance compared to the non-PT vein segments (5 mm2 vs. 10 mm2 and 13 mm2 at a pressure change of 40 cm H2O). Compliance had no statistical difference between venous hypertension (VHT) and Control. Compliance at PT stenosis, however, was significantly smaller than that at Control and VHT (p &amp;lt; 0.05, ANOVA).Conclusion: The CMSB system provides accurate, repeatable, real-time measurements of CSA and compliance for assessment of venous lesions to guide interventions. These findings provide the impetus for future first-in-human studies.

The heterogeneous precipitation behavior of Al-Zn-Mg-Cu alloy was studied by high-throughput experiment based on end-quenching technology

Based on the quenching experiments and in combination with electrical conductivity measurements and microstructural characterization, the non-uniform precipitation behavior of the 7055 alloy was investigated. The study revealed that as the quenching rate decreased from 20.8 °C/s to 2.25 °C/s, the electrical conductivity increased from 27.8 %IACS to 30 %IACS, and both the types and nucleation sites of quenching-induced precipitates increased. The favorable nucleation sites for the precipitation were identified in the following sequence: high-angle grain boundaries (HAGBs), low-angle grain boundaries (LAGBs), non-coherent Al3Zr particles, dislocations, and coherent Al3Zr particles. The sequence of non-uniform precipitate formation included η, S, T, and Y phases. With the reduction in quenching rate, the η phase successively precipitated on HAGBs, LAGBs, non-coherent Al3Zr particles, and coherent Al3Zr particles. At a quenching rate of 10.5 °C/s, not only was the S phase observed to precipitate at high-density dislocation subgrains (SGs), but also the T phase was observed to precipitate at the non-coherent Al3Zr particles and subgrain boundaries (SGBs). When the quenching rate was further reduced to 2.7 °C/s, the precipitation of the Y phase was observed at SGs dislocations, and simultaneously, the precipitation of the η and T phases was observed on the coherent Al3Zr particles within the SGs.

High-pressure synthesis of half-doped perovskites MnV0.5Nb0.5O3 and MnV0.5Ta0.5O3 with unusual A-site small Mn2+ cations

ABSTRACT We have successfully synthesized two new half-doped perovskites, MnV0.5Nb0.5O3 and MnV0.5Ta0.5O3, with unique small Mn2+ cations at the A site under high-temperature and high-pressure conditions (6 GPa and 900–1300 °C). Synchrotron X-ray structure analysis confirmed their crystal structures to belong to the space group Pnma, and they do not exhibit features of an ordered perovskite (double perovskite) structure. Magnetic property measurements revealed an essentially antiferromagnetic nature below 17 and 18 K for both compounds, respectively, accompanied by a small contribution of thermal and magnetic field hysteresis. Electrical conductivity measurements showed activation energies of 0.13 and 0.31 eV, respectively, suggesting semiconductor-like behavior. These findings underscore the potential of these materials with unusual A-site small Mn2+ cations for electronic and magnetic devices, warranting further studies to explore their unique magnetic and electronic properties.