Electrical Relaxation Research Articles

Efficient model for electronic transport in high energy-density matter

A wide-ranging effective Boltzmann approach, originally intended for ionic transport, is applied to the computation of electronic transport coefficients without modification. Comparisons with datasets that resulted from a recent transport coefficient workshop and molecular dynamics simulations are made. While this model contains correlation information through its effective potential and strong scattering through its use of cross sections, it misses details of attractive, possibly quantum, interactions; comparisons with that dataset reveal the relative importance of these physics inputs. Through comparisons of data for electrical conductivity, thermal conductivity, temperature relaxation, and stopping power (including a new formula for the energy split due to alpha stopping), we find that the sensitivity to the missing physics is minor and often negligible. Thus, we have a single transport model that self-consistently provides all ionic and electronic transport properties in a form with negligible computational cost.

Hopping frequency and conductivity relaxation of promising chalcogenides: AC conductivity and dielectric relaxation approaches

Ag2S doped chalcogenide glassy systems have been characterised on the basis of AC conductivity and electric modulus formalism. Various nanophases such as Ag2Se, Te0.5 Se3.5 etc. and dislocation (defects) have been identified and their roles in the conduction process have been established. XRD analysis provides that incorporation of more Ag2S content in the present system should play important role to enhance the dislocation and to decrease the crystallite sizes. The Fourier transform infrared spectra (FT-IR) confirm the characteristic vibration of Ag–S at 500–650 cm−1, stretching vibrations of the O–H bond near 3400 cm−1 and bending vibrations of the adsorbed H2O molecules on the surface of Ag2S near 1600 cm−1. Composition dependent optical phonon frequency (ν0) and Debye temperature (θ D) have been estimated from FT-IR and it is noteworthy that θ D increases with Ag2S content in the compositions up to x = 0.1, but decreases for x = 0.2. This result suggests higher kinetic energy of the constituent atoms/molecules, which may refer to higher electrical conductivity due to polaron hopping. Correlated barrier hopping (CBH) model in its modified version has been found most suitable model to explore the conduction mechanism. Short time relaxation process may be considered to be trivially associated with conduction of polaron. universal scaling approach proposed by Ghosh and Pan has been adopted to interpret electrical relaxation process from time-temperature superposition principle. AC conductivity spectra at various temperatures exhibit a perfect overlap into a single master curve. This feature must be an indication of the temperature independent relaxation process. On the other hand, conductivity spectra of all the compositions at a particular temperature do not exhibit perfect overlapping into a single master curve. This result indicates that the relaxation dynamics of charge carriers (polarons) is strongly dependent on compositions.

Analysis of Epoxy Nanocomposites Characteristics by Impedance Spectroscopy

AbstractThe research work is carried out to analyse the electrical characteristics of glass fiber reinforced epoxy composites with the addition of multiwall carbon nanotubes and graphene nanoplatelets. The dispersion of 2wt.% multi walled carbon nanotubes(MWCNT) and 1‐3wt.% graphene nanoplatelets (GNP) into the epoxy resin is assisted with high shear mechanical mixing followed by ultrasonication. The epoxy‐filler mixture is transferred into temperature‐controlled resin bath for pultrusion process. The pultrusion process helps to resolve major issues like poor dispersion and agglomeration of nanofillers in epoxy resin. The XRD and SEM analysis indicates that fillers are dispersed homogeneously in the epoxy matrix. The electrical conductivity (σ) and impedance (Z) are studied in the frequency range (10 Hz‐8 MHz) with the variation in temperature (over 25 °C‐150 °C). It is observed that the addition of two conductive nanofillers results in a synergistic effect at the percolation threshold, and the conductivity value increases by few orders due to the formation of a number of conductive paths in the composite. The complex impedance decreases with increase in frequency for the composites except for the sample with 3wt.% GNP and 2wt.% MWCNT indicating the semiconducting behaviour. The complex impedance plot is characterized by the appearance of a single semi‐circular arc whose radii of curvature decreases with an increase in temperature, indicating the existence of electrical relaxation phenomena.

Cation Diffusion in Non-Stoichiometric (La, Sr)MnO3/CeO2 Nano-Composite Cathode

Co-sintering of stacks or cells containing electrodes, electrolytes, and separators is essential fabrication technology to improve power density per unit volume significantly. Generally, cathode materials have low heat-resistant temperatures, and they are easily decomposed or degraded by sintering at a high temperature. (La0.8Sr0.2) MnO3 (LSM) shows relatively high resistance and preferable low-reactivity with fluorite electrolytes during sintering at a high temperature. But it shows lower cathodic properties than lanthanum strontium cobaltite or lanthanum strontium cobalt ferrite because of poor oxygen diffusion. Thus, we have investigated LSM/ceria nanocomposite to improve oxygen diffusion.Nanocomposite precursor powder containing LSM and ceria was synthesized by glycine method. The composite ratio of LSM and ceria was fixed at 9:1 (molar ratio). The dense composite compact was obtained by sintering the powder at 1200oC for 5 h in air, and fine ceria particles were homogeneously dispersed with LSM. Electrical conductivity and oxygen diffusion coefficient were estimated with these dense composites. Oxygen diffusion coefficients were estimated by electrical conductivity relaxation method. The amount of cation dissolved in ceria was investigated from XRD peak shifts. The defect of La or Sr in LSM formed by sintering with ceria was estimated with magnetic properties of LSM and LSM/ceria nanocomposite. The defect was also investigated using the relationship between activation energy and composition of a-site defect LSM or La-defect LSM.LSM showed a low oxygen diffusion coefficient, and the coefficient of LSM/ceria nanocomposite was much improved even though ceria composite ratio is 10%. However, LSM/ceria composite showed much lower conductivity than LSM since a-site cation of LSM, La or Sr, may be easily diffused into ceria. XRD peaks derived from only ceria were shifted toward lower angle for LSM/ceria nanocomposite prepared under various sintering conditions. The shift revealed that 2-5% La in LSM was diffused into ceria, assuming that only La is diffused. Diffusion of La into ceria increases in oxide ionic conductivity and the diffusion would benefit the composite's cathodic properties in terms of oxygen diffusion. However, if the diffusion would bring about La defect LSM and deviations from the optimum composition, the diffusion would be detrimental in terms of electrical conductivity.Then we investigated the effects of the diffusion on the defect structure of LSM in LSM/ceria nanocomposite by magnetic properties and electrical conductivities. Assuming that only La of LSM was diffused into ceria, the loss amount of La from LSM was estimated with magnetic phase transition temperatures for LSM and LSM/ceria nanocomposite. The temperatures were measured by SQUID. The overall loss amount of La from LSM was increased according to solid solution of La in ceria. But, the loss amount was slightly different from the solution amount to ceria.The ionic radius of Sr2+ is similar to that of La3+. Dissolution of Sr in ceria also leads to XRD peaks shift toward lower angle as well as that of La. Then, we investigate whether the loss from LSM was derived from only La (La-defect LSM) or both La and Sr ( a-site-defect LSM). La-defect and a-site-defect LSM dense ceramics with various defect concentrations were prepared by glycine method. Activation energy of these LSM ceramics was estimated from the temperature dependence of electrical conductivity measured in air. That of La-defect LSM was monotonically decreased with increasing defect concentration. A-site-defect LSM showed no significant change in activation energy within the defect concentration less than 8%. The relationship between activation energy of LSM/ceria nanocomposite and the defect concentration of LSM was measured using various sintering conditions. The relationship showed the activation energy of LSM/ceria was almost independent of the defect concentration. Therefore, Sr would simultaneously diffuse from LSM to ceria during sintering LSM/ceria nanocomposite. Electrical degradation of LSM/ceria nanocomposite would be derived from Sr defect of LSM as well as La.

Modeling electro-osmotic flow and thermal transport of Caputo fractional Burgers fluid through a micro-channel

In this paper, we construct transient electro-osmotic flow of Burgers’ fluid with Caputo fractional derivative in a micro-channel, where the Poisson–Boltzmann equation described the potential electric field applied along the length of the microchannel. The analytical solution for the component of the velocity profile was obtained, first by applying the Laplace transform combined with the classical method of partial differential equations and, second by applying Laplace transform combined with the finite Fourier sine transform. The exact solution for the component of the temperature was obtained by applying Laplace transform and finite Fourier sine transform. Further, due to the complexity of the derived models of the governing equations for both velocity and temperature, the inverse Laplace transform was obtained with the aid of numerical inversion formula based on Stehfest's algorithms with the help of MATHCAD software. The graphical representations showing the effects of the time, retardation time, electro-kinetic width, and fractional parameters on the velocity of the fluid flow and the effects of time and fractional parameters on the temperature distribution in the micro-channel were presented and analyzed. The results show that the applied electric field, electro-osmotic force, electro-kinetic width, and relaxation time play a vital role on the velocity distribution in the micro-channel. The fractional parameters can be used to regulate both the velocity and temperature in the micro-channel. The study could be used in the design of various biomedical lab-on-chip devices, which could be useful for biomedical diagnosis and analysis.

Performance of PrBaCo2O5+δ impregnated La0.6Sr0.4Co0.2Fe0.8O3−δ composites as potential cathode materials for solid oxide fuel cells

The solution impregnation method was used to manufacture double perovskite PrBaCo2O5+δ (PBCO) impregnated La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) skeleton composite electrodes. The effects of different PBCO impregnation loadings on the electrochemical performance were investigated by experimental methods. Electrochemical impedance spectroscopy (EIS) results show that a proper amount (the mass of PBCO particles on the surface of electrode is about 10 wt% of LSCF framework) of PBCO impregnation significantly promotes the performance of original LSCF cathode, which reaches the polarization resistance (Rp) of 0.086 Ω cm2 at 750 °C. Meanwhile, excessive impregnation of PBCO increases the Rp value of LSCF cathodes on the contrary. PBCO impregnation mainly affects the low-frequency region of the composite electrode, which is also confirmed by the electrical conductivity relaxation (ECR) and O2 temperature programmed desorption (O2-TPD) measurements. The concentration of oxygen vacancy and the oxygen adsorption capacity of the PBCO-LSCF composite electrodes were improved, thereby promoting its electrochemical performance. Moreover, the existence of the LSCF skeleton improves the mismatch problem of the thermal expansion coefficient between PBCO and GDC electrolyte.

Low‐Temperature Protonic Ceramic Fuel Cells through Interfacial Engineering of Nanocrystalline BaCe0.7Zr0.1Y0.1Yb0.1O3−δ Electrolytes

Nanocrystalline BaCe0.7Zr0.1Y0.1Yb0.1O3−δ (BCZYYb) is designed by a novel strategy with improved proton transport properties at low temperatures (<300 °C). In situ Raman spectroscopy and electrical conductivity relaxation (ECR) are used to quantitatively evaluate the surface exchange coefficients during the hydrogen isotope exchange process. Similar surface exchange coefficients are measured via in situ Raman spectroscopy and ECR measurements, representing new tools to better understand proton transport behaviors at the materials’ interface. The surface exchange coefficient in nanocrystalline BCZYYb is nearly four times higher than that in conventional dense BCZYYb at 300 °C, indicating higher surface mobility of protonic species in the designed BCZYYb membrane. The improved performance originates from the combined interfacial and bulk effects for proton transport at low temperatures. In addition, low‐temperature protonic ceramic fuel cells (PCFCs) are built based on a nanocrystalline BCZYYb electrolyte with improved single‐cell performance at 300 °C, which indicates enhanced proton transport properties in contemporary energy conversion and storage materials can be achieved through interfacial engineering.

Effect of Cr addition on the structure and electrical properties of CaCu3Ti4O12 NTC thermistor

In the present work, CaCu3-xCrxTi4O12 (CCCTO, 0 ≤ x ≤ 1) ceramics were prepared by a solid-state reaction. The influence of Cr on the structure and electrical properties of the CCCTO ceramics was investigated in detail. X-ray diffractometry (XRD) revealed that all samplesʼ main phases were CaCu3Ti4O12 (CCTO), but CuO and CaTiO3 phases were also found. Cr doping suppressed the abnormal growth of grains, thus the grain size distribution became more uniform with the increase of Cr doping content. The resistance-temperature analysis revealed that all CCCTO ceramics had a noticeable Negative Temperature Coefficient (NTC) effect. The resistivity ρ30 of the CCCTO ceramics decreased from 1.15 × 106 to 8.73 × 104 Ω cm with an increase in the value of x, along with a decrease in the thermal constant B from 6596 to 3267 K. It was also observed that both the grain and grain-boundary effects contributed to their NTC characteristics. The analysis revealed that the conductivity of the ceramics arose mainly from the electron hopping mechanism. All the samples showed an electrical relaxation behavior. The observations indicated that the structures and electrical properties of CCCTO ceramics could be attuned precisely by adjusting the concentration of the Cr2O3 doping agent.

Oxygen exchange and bulk diffusivity of BaCo0.4Fe0.4Zr0.1Y0.1O3-δ: Quantitative assessment of active cathode material for protonic ceramic fuel cells

The oxygen surface exchange and bulk diffusivity of BaCo0.4Fe0.4Zr0.1Y0.1O3-δ were determined by electrical conductivity relaxation (ECR) in order to quantitively assess cathode performance for protonic ceramic fuel cells (PCFCs). The measurements were performed at 600 °C, following pO2-step changes between 80 ppm to pure oxygen. The apparent value of surface exchange coefficient (k) and diffusion coefficient D, indicates BaCo0.4Fe0.4Zr0.1Y0.1O3-δ is a good oxygen conductor. k was found to vary with pO2 and surface area while the chemical diffusion coefficient D remained invariant with pO2 and surface coating. The fitted kinetic parameters obtained from ECR with reduction process (high to low pO2) were compared with that of the oxidation process (low to high pO2). In the presence of H2O, oxygen exchange kinetics was suppressed because of the competitive adsorption relationship between oxygen and H2O. Single cell measurements employing single phase BaCo0.4Fe0.4Zr0.1Y0.1O3-δ cathode and an anode prepared by phase inversion tape casting in a configuration of 40 wt% BCZYSm13 + 60 wt% NiO | BCZYSm13 | BCFZY0.1 exhibited a power density of ~200 mW/cm2 at 600 °C.

Role of porosity on the equilibration kinetics in electrical conductivity relaxation experiments

The role of porosity on the equilibration kinetics in electrical conductivity relaxation (ECR) experiments is highlighted. Both porous and dense conductivity bars are used to determine the chemical oxygen surface exchange coefficient (kchem) of neodymium nickelate Nd2NiO4+δ (NNO) from 600 to 800 °C. Using porous bars allows for quicker ECR experiments during which the conductivity transient is rate limited only by oxygen surface exchange which enables the use of a simple transient model. Additionally, porous bars have similar microstructures to porous electrodes which means they are critical for determining the oxygen exchange kinetics of realistic electrodes. ECR results on dense bars with porous coatings are also presented. The conductivity transients of dense and porous bars both show similar trends with oxygen partial pressure. Additionally, both porous and dense bars show a difference between oxidation and reduction transients with oxidation transients being faster than reduction transients.

On the Electrical Resistance Relaxation of 3D-Anisotropic Carbon-Fiber-Filled Polymer Composites Subjected to External Electric Fields.

Flexible composites as sensors are applied under a small voltage, but the effect of the external electrical field on the resistance is always ignored and unexplored by current research. Herein, we investigate the electrical resistance relaxation of anisotropic composites when they are subjected to an external electric field. The anisotropic composites were 3D-printed based on carbon-fiber-filled silicon rubber. Constant DC voltages were applied to the composites, and the output electrical current increased with time, namely the electrical resistance relax with time. The deflection and migration of carbon fibers are dominantly responsible for the resistance relaxation, and the angle’s evolution of a carbon fiber, under the application and removal of the electrical field, was well observed. The other factor hindering the resistance relaxation is the increased temperature originating from the Joule heating effect. This work provides a new understanding in the working duration and the static characteristics of flexible composites.

Synthesis, structural, electrical and electrochemical investigations of CoNi2S4 thin films for solid fuel applications

CoNi2S4 ternary sulfide thin films are deposited on glass substrates by spray pyrolysis at 250 °C using an aqueous solution of chloride hexahydrate (NiCl2,6H2O),tin chloride hexahydrate (CoCl2, 6H2O) and thiourea (SC(NH2)2) (ACROS pure more than 99.0%). Structural study using X-ray diffraction are allowed; lattice parameters and structural defects where studied. Morphological properties are carried out by using both AFM and SEM observations. Optical properties are performed by means of transmittance and reflection measurements as well as photoluminescence measurements. On the other hand, electrical properties are investigated in terms of electrical conductivity, free carrier and relaxation time at different temperatures through Hall effect and four probes measurements. This investigation shows a metallic behavior of this current II-IV2VI4 ternary compound. Finally, the advances in the actively studied electrode that are emerging as effective alternate for CoNi2S4based cyclic voltammetry are also discussed.

Influence of Heterointerfaces on the Kinetics of Oxygen Surface Exchange on Epitaxial La1.85Sr0.15CuO4 Thin Films

Considerable attention has been directed to understanding the influence of heterointerfaces between Ruddlesden–Popper (RP) phases and ABO3 perovskites on the kinetics of oxygen electrocatalysis at elevated temperatures. Here, we report the effect of heterointerfaces on the oxygen surface exchange kinetics by employing heteroepitaxial oxide thin films formed by decorating LaNiO3 (LNO) on La1.85Sr0.15CuO4 (LSCO) thin films. Regardless of LNO decoration, tensile in-plane strain on LSCO films does not change. The oxygen surface exchange coefficients (kchem) of LSCO films extracted from electrical conductivity relaxation curves significantly increase with partial decorations of LNO, whereas full LNO coverage leads to the reduction in the kchem of LSCO films. The activation energy for oxygen exchange in LSCO films significantly decreases with partial LNO decorations in contrast with the full coverage of LNO. Optical spectroscopy reveals the increased oxygen vacancies in the partially covered LSCO films relative to the undecorated LSCO film. We attribute the enhanced oxygen surface exchange kinetics of LSCO to the increased oxygen vacancies by creating the heterointerface between LSCO and LNO.

Effect of Eu3+ ions on electrical and dielectric properties of barium hexaferrites prepared by solution combustion method

This paper reports the electrical conduction behaviour of Eu3+ substituted barium hexaferrites (BaM) prepared via solution combustion method. The structural analysis confirms formation of hexagonal phase of the prepared samples with a space group p63/mmc (No. 194). The SEM micrographs show that the prepared sample has hexagonal plate like structure. Dielectric constant, dielectric loss and AC conductivity of the prepared samples were calculated over a wide frequency range from 102 Hz to 105 Hz at different temperatures. The temperature dependent dielectric studies were also performed over a temperature range of 30°C–200°C. The non –Debye dielectric nature of the prepared samples and presence of electrical relaxation phenomenon were confirmed from the complex impedance spectroscopy. Electrical modulus analysis confirms that there is negligible electrode effect in prepared the samples. From the frequency dependent AC conductivity studies, we find that the AC conductivity values are constant in the lower frequency region and shift towards the higher value in the higher frequency region, which indicates that the prepared samples follow the Almond-West power law. The AC conductivity values decrease gradually with increase in the concentration of Eu3+ ions increases. The dielectric studies show that by doping of Eu3+ ions, the dielectric constant increases. So the prepared materials can be applicable for microwave devices applications.

Correlating Surface Crystal Orientation and Gas Kinetics in Perovskite Oxide Electrodes.

Solid-gas interactions at electrode surfaces determine the efficiency of solid-oxide fuel cells and electrolyzers. Here, the correlation between surface-gas kinetics and the crystal orientation of perovskite electrodes is studied in the model system La0.8 Sr0.2 Co0.2 Fe0.8 O3 . The gas-exchange kinetics are characterized by synthesizing epitaxial half-cell geometries where three single-variant surfaces are produced [i.e., La0.8 Sr0.2 Co0.2 Fe0.8 O3 /La0.9 Sr0.1 Ga0.95 Mg0.05 O3-δ /SrRuO3 /SrTiO3 (001), (110), and (111)]. Electrochemical impedance spectroscopy and electrical conductivity relaxation measurements reveal a strong surface-orientation dependency of the gas-exchange kinetics, wherein (111)-oriented surfaces exhibit an activity >3-timeshigher as compared to (001)-oriented surfaces. Oxygen partial pressure ( )-dependent electrochemical impedance spectroscopy studies reveal that while the three surfaces have different gas-exchange kinetics, the reaction mechanisms and rate-limiting steps are the same (i.e., charge-transfer to the diatomic oxygen species). First-principles calculations suggest that the formation energy of vacancies and adsorption at the various surfaces is different and influenced by the surface polarity. Finally, synchrotron-based, ambient-pressure X-ray spectroscopies reveal distinct electronic changes and surface chemistry among the different surface orientations. Taken together, thin-film epitaxy provides an efficient approach to control and understand the electrode reactivity ultimately demonstrating that the (111)-surface exhibits a high density of active surface sites which leads to higher activity.

Narrow bandgap ferroelectric semiconductors within BiFeO<sub>3</sub>-based solid solution perovskites

<p indent=0mm>Solar energy is a clean and renewable source of energy. Various solar photovoltaic (PV) cell technologies have been developed, out of which perovskite PV cell technology is growing rapidly. Using organometal halide perovskite as an optical absorption component, the power conversion efficiency (PCE) of heterojunction solar PV cells increased from 3.8% in 2009 to 25.5% recently. Nonetheless, the bottleneck for CH₃NH₃PbI₃-based solar cells entering into commercial market is their poor stabilities relating to environmental, thermal, and ultraviolet light influence. In contrast, transition metal oxide perovskites are thermodynamically and chemically stable enough for solar cells’ commercialization, with more advantages such as bandgap (<italic>E</italic>_g) adjustability from <sc>0 to 6 eV,</sc> processing being compatible with transparent conducting oxides, and ferroelectric bulk PV effect. Owing to a wide <italic>E</italic>_g, traditional ferroelectric perovskite oxides exhibit poor visible optical absorption, low electrical conductivity, and thus extremely low PCE. As an alternative to p-n junction PV effect, ferroelectric bulk PV effect provides a new separation mechanism for photo-excited carriers, which is closely related to spatial inversion symmetry breaking and its resulting spontaneous electric polarization. Different from p-n junction, the active space for photo-excited carrier separation spans the whole ferroelectric body, and thus an above-<italic>E</italic>_g open-circuit voltage is produced. By narrowing <italic>E</italic>_g while maintaining ferroelectricity of oxide perovskites, ferroelectric semiconductors become available to monolithically integrate the p-n junction and ferroelectric bulk PV effects, which could, in principle, go beyond the Shockley-Queisser theoretical PCE limit of conventional<italic> </italic>p-n junction solar cells. Bismuth ferrite (BiFeO₃) has been experimentally demonstrated to exhibit ferroelectric PV effect. Meanwhile, it has a high ferroelectric Curie temperature (<italic>T</italic>_C) of 830°C and an intermediate <italic>E</italic>_g of <sc>~2.2 eV,</sc> providing a large chemical space for solid solution perovskite oxides to trade off both target properties of narrow <italic>E</italic>_g and <italic>T</italic>_C><sc>400 K.</sc> In this report, 0.50BiFeO₃-0.25A₁MnO₃-0.25A₂TiO₃ (A₁ = Ca, Sr, Ba, A₂ = Sr, Ba, Pb) and 0.49BiFeO₃-0.26BaTiO₃-0.25(Sr₁₋_{<italic>x</italic>}Ba_{<italic>x</italic>})(Co_1/3Nb_2/3)O₃ (<italic>x </italic>= 0 and 0.4) ferroelectric semiconductors with <italic>E</italic>_g of <sc>~0.9 eV</sc> were created by substituting Fe³⁺ with Mn⁴⁺ or Co²⁺ in BiFeO₃-based solid solution perovskites. Ceramic samples were prepared using a refined solid-state reaction electroceramic processing. X-ray diffraction measurements showed them crystallized in a single pseudo-cubic perovskite phase, while Raman scattering characterizations illustrated a breaking of spatial inversion symmetry at room temperature. Optical absorbance measurements found that these Mn⁴⁺- or Co²⁺-substituted BiFeO₃-based solid solution perovskites have a direct bandgap in a range of <sc>0.75–1.0 eV.</sc> Compared with CH₃NH₃PbI₃ perovskites, their optical absorption reaches near-infrared band of solar spectra. Temperature-dependent resistance measurements showed their resistivity on the magnitude of order of <sc>~10⁶ Ω cm</sc> with thermal excitation energy (<italic>E</italic>_a) of <sc>~0.5 eV.</sc> Combined with observation of frequency-dependent dielectric properties, A-site vacancies were proposed responsible for electrical conduction and dielectric relaxation. Through data-mining causal relationships between <italic>E</italic>_g and the filling number of d electron of B-site cations, <italic>μ</italic>×<italic>r</italic>_A/<italic>r</italic>_B ensemble descriptor of oxide perovskites (<italic>μ</italic>, <italic>r</italic>_A, and <italic>r</italic>_B are the reduced mass of primitive cell, A-site cation radius, and B-site cation radius, respectively), a physical model was proposed to predictively design chemical compositions of ferroelectric semiconducting oxide perovskites with <italic>E</italic>_g<sc>~0.9 eV</sc> for applications of solar PV cells. This essay provides an opportunity for developing novel solar PV cells to integrate monolithically p-n junction and ferroelectric bulk PV effects, with PCE beyond the Shockley-Queisser theoretical limit.

Gold particle effect on high temperature oxygen reduction reaction via lanthanum strontium cobaltite ferrite electrocatalyst

Gold is generally considered to be inert for electrochemical reactions in solid oxide fuel cells (SOFCs). It is thus used as the standard current collector to characterize the catalytic activity of various cathode materials including the state-of-the-art lanthanum strontium cobalt iron oxide (LSCF). This work shows that gold is not inert but active for oxygen reduction reaction (ORR) via LSCF. Electrical conductivity relaxation measurement shows that scattered gold particles on LSCF surface can greatly increase the ORR rate. Gold improves the chemical oxygen surface exchange coefficient by a factor up to 27.5. The improvement is much high at reduced temperature from 800 to 650 °C. In addition, gold particles with smaller size show better performance in enhancing the ORR activity.

Electric Field Simulation of Permittivity and Conductivity Graded Materials (ε/σ-FGM) for HVDC GIS Spacers

This paper discusses the application of the novel technology - functionally graded material (FGM), which combines both spatial permittivity (ε) and conductivity (σ) distributions with the aim to control the electric field around DC-GIS spacer. Some distribution types of ε and/or σ in the spacer bulk, such as U-type and graded to higher conductivity (GHC) are investigated through electric field simulation, in comparison to the uniform spacer with constant ε and σ distributions. The electric field relaxation effect of each distribution type of ε/σ-FGM under DC steady state, DC polarity reversal, DC-on, and lightning impulse voltage superimposed on DC steady state condition are obtained. The results show that ε/σ-FGM with U-type permittivity and GHC-type conductivity distribution of which low σ is applied near the high voltage side of the DC-GIS spacer is the most effective in reducing the maximum electric field under all stated conditions.

Comparative Characteristics of Pregnancy Course and Labour Outcomes in Pregnant Women, Depending on Observation Conditions and Location of Health Improvement Activities

Recurrent pregnancy loss (RPL) is quite an urgent problem in modern obstetric practice, as it has an important effect on perinatal morbidity and mortality, as well as on women's reproductive health. In the treatment of pregnancy loss, specialists have few attempts, and the doctor is responsible for diagnostic assessment, management and place of treatment. Purpose of study: To compare characteristics of pregnancy course and labour outcomes in pregnant women, depending on observation conditions and location of health improvement activities Materials and methods: Group I included 206 pregnant women, receiving in-patient treatment at the sanatorium; and 147 (group II), who were treated in the pathologic pregnancy department in the maternity hospital, were assigned to the risk group for pregnancy loss. At this, 45 patients in group I and 43 patients in group II 43 were treated for threatened miscarriage. Among women from the risk group of pregnancy loss in more than 70% of cases, a burdened obstetric and gynaecological history was revealed. Pregnant women with threatened pregnancy loss at the sanatorium received a complex therapeutic and preventive treatment, including consultations with a psychotherapist (auto-training), physiotherapy, vitamin therapy, herbal medicine, acupuncture. Pregnant women, belonging only to the risk group for pregnancy loss, received a preventive course of central electrical analgesia (CEA), psychophysiological training and general sanatorium regimen. The therapy was combined with test cardiac monitoring. The therapeutic measures in pathologic pregnancy department in the maternity hospital were limited to bed rest and medical therapy, vitamin therapy, prescription of sedatives and tocolytic therapy. Some pregnant women were treated using physical treatment methods - electric relaxation according to A.Z. Haskin on Amplipulse-4 device. Results: The performed study demonstrates that pregnant women, treated in the sanatorium, were less likely to suffer from gestational toxicosis, threatened miscarriage and anaemia of pregnant women. In women of group I, compared to group II, in a large percentage the delivery was in time and natural. In the pathologic pregnancy department, the following complications were recorded: poor uterine contraction strength and bleeding in the 3rd period. Conclusion: In women with RPL, it is recommended to include a sanatorium stage in the system of specialized care for such patients to prolong pregnancy, normalize psycho-emotional state and reduce the number of postnatal complications.

Macrophage-Specific Toll Like Receptor 9 (TLR9) Causes Corpus Cavernosum Dysfunction in Mice Fed a High Fat Diet

BackgroundErectile dysfunction (ED) has been shown to be related with inflammatory markers in humans. Chronic infusion of TNF-α caused ED in mice while TNF-α knockout mice exhibited improvement in the relaxation of the corpus cavernosum (CC). AimSince obesity triggers an inflammatory process, we aimed to investigate the hypothesis that in obesity, Toll-like receptor 9 (TLR9) activation leads to increased TNF-α levels and impairment in CC reactivity. MethodsFour-week old male C57BL6 (WT) and TLR9 mutant (TLR9MUT) mice were fed a standard chow or high fat diet (HFD) for 12 weeks. Body weight and nonfasting blood glucose were analyzed. Contractile and relaxation responses of the CC were evaluated by electrical field stimulation and concentration response curves to phenylephrine and acetylcholine. Protein expression of nNOS, TNF-α, TNF-R1, TLR9 and MyD88 were measured by western blot. Plasma levels of TNF-α were measured by ELISA. OutcomeIn obesity, impaired cavernosal relaxation is associated with the activation of the innate immune system, by increasing the production of TNF-α through the activation of TLR9 in the macrophages. ResultsAfter 12 weeks of HFD both WT and TLR9MUT mice had increased body weight and nonfasting blood glucose compared to standard chow. In the CC, acetylcholine-induced relaxation was not changed. A trend to increased contraction to phenylephrine and KCl was seen in WT HFD only. electrical field stimulation-induced relaxation of the CC was decreased in WT HFD as well as nNOS expression in the CC of WT HFD, but not in TLR9MUT HFD. In the CC, protein expression of TLR9 and MyD88 was similar in all groups. While circulating levels of TNF-α presented only a trend to increase in mice fed HFD, the CC expression of TNF-α was increased only in WT HFD mice. Clinical TranslationThe innate immune system can be a target for the treatment of erectile complications in obesity. Strengths and LimitationsThis is the first study demonstrating that activation of TLR9 expressed in macrophages leads to impaired cavernosal relaxation. The main limitation of the study is the lack of understanding about the source/expression of the macrophages in the cavernous tissue. Further, herein, the experiments were performed only in isolated cavernous tissue (in vitro), thus the lack of knowledge on how the TLR9 modulates the in vivo response of the erectile tissue is another limitation of this study. ConclusionOur findings indicate that CC dysfunction observed in obesity is at least in part mediated by the production of TNF-α upon activation of TLR9 expressed in the macrophages. Priviero F, Calmasini F, Dela Justina V, et al. Macrophage-Specific Toll Like Receptor 9 (TLR9) Causes Corpus Cavernosum Dysfunction in Mice Fed a High Fat Diet. J Sex Med 2021;18:723-731.