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The microwave sintered NiTiO 3 nanoparticles were synthesized by sol-gel method. The synthesized compound is found to be rhombohedral crystal structure and crystallite size of 46 nm from X-ray powder diffraction technique. The metal-oxide Ni-O and Ti-O bands were analyzed by Fourier Transform Infra-Red analysis. The average particle size is found to be 56 nm from High Resolution Scanning Electron Microscope analysis. The activation energy calculated from Arrhenius plot, the value is found to be 0.04 μeV. The M r value is found to be 0.22 emu/g. At room temperature NiTiO 3 exhibited superparamagnetic nature. [ABSTRACT FROM AUTHOR]

NiO thin films have been successfully synthesized using by successive ionic layer absorption and reaction (SILAR) technique which is simple, cost-effective and low-temperature wet chemical process. Influences of deposition cycle on structural and morphological property were investigated using XRD and FESEM. Surface morphological study shows formation of highly porous network which provides more active sites and deposition path for electrolyte ions. NiO thin film based electrode provides highest specific capacitance of 1341 Fg −1  at the voltage scan rate of 2 mVs −1 for the film deposited at 40 deposition cycle. From charging -discharging curve of NiO electrode, specific capacitance value of 877 Fg −1  at current 1 Ag −1 for the film deposited at 40 deposition cycle was observed. It shows highest specific energy of 64.8 Wh Kg −1 . The NiO electrode exhibited long-term cycle stability with 90% capacitance retention after 1000 cycle. Such attractive electrochemical performance of the formed electrode is suitable for the manufacturing of the good quality supercapacitors for commercial application. [ABSTRACT FROM AUTHOR]

Fabrication of TiO2 nanotubes-based solid-state vapor sensor (Au/TiO2 nanotubes/Ti) and its performance analysis for both resistive- and capacitive-mode sensing mechanisms are discussed here. Highly ordered TiO2 nanotubes array has been synthesized by the electrochemical anodization technique. Structure and morphology of the as-grown TiO2 nanotubes have been characterized using X-ray diffraction and field-emission scanning electron microscopy. X-ray photoelectron spectroscopy has been used to study the chemical states of the TiO2 nanotubes. The sensor device has successfully been tested for ethanol vapor. The effect of temperature, pressure, and reducing ambient (i.e., partial pressure of ethanol vapor) has been studied using the impedance analysis method. The resistive and capacitive components of the impedance were measured individually. The sensor resistance decreased by 93.38%, whereas the capacitance increased by 28789.95% after an exposure to 1000 ppm of ethanol. Both the resistive and capacitive sensing performance of Au/TiO2 nanotubes/Ti device have been correlated with the proposed circuit model to achieve an improvised vapor sensing. [ABSTRACT FROM AUTHOR]

Sodium lithium sulfide (NaLiS) nanocomposite have been successfully synthesized by using microwave-irradiation (MWI) method. The study suggested that the application of microwave heating is to produce homogeneous and fine NaLiS nanocomposite which were achieved by using the precursors of lithium acetate and thioacetamide in the presence of sodium alginate biopolymer. FTIR is used to identify the structural coordination and functional groups of the prepared nanocomposite. The structural property of NaLiS particles was investigated by XRD. The surface morphology and elemental composition of synthesized material was confirmed by SEM and EDX analyses. The optical property was studied by using UV-Vis spectrophotometer. Thermal stability of as prepared sample was studied by TGA/DTG analysis. Electrical transport studies of the prepared nanocomposite have been analyzed for various temperatures. NaLiS nanocomposite has ionic conductivity of ~ 10−7 S cm−1 at 35 °C which is six orders of magnitude higher than that of micro sized bulk Li2S (~ 10−13 S cm−1). [ABSTRACT FROM AUTHOR]

High-frequency oscillation is one of the critical issues threatening the stability of modular multilevel converter (MMC) based high-voltage direct current (HVDC) system. A new 2 kHz high-frequency oscillation has occurred in the wind farm-side MMC station of Rudong wind farm integrated MMC-HVDC project of China during no-load charging process. The mechanism of this high-frequency oscillation is different to previous ones. Apart from the time delay of MMC, the stray capacitance of converter transformer makes a significant contribution to the high-frequency oscillation. This paper investigates the high-frequency oscillation mechanism of wind farm-side MMC station during no-load charging process. First, the harmonic state space (HSS) model of a wind farm-side MMC station is established. In addition to the leakage inductance, the stray capacitance is considered in the converter transformer model. To reveal the significance of the converter transformer stray capacitance in this new high-frequency oscillation, the root loci of the system are calculated with varying stray capacitance. Then, the state variables with high degree of participation in the high-frequency oscillation modes are determined by the participation factor analysis. A reduced-order model suitable for the high-frequency oscillation analysis is further established based on the participation factor analysis results. Next, the high-frequency oscillation mechanism is revealed by impedance analysis. Finally, the effects of system parameters are analyzed by the combination of eigenvalue analysis and impedance analysis. The analysis results are validated by electromagnetic transient simulations. • High-frequency oscillation mechanism of MMC charging with transformer is revealed. • The transformer stray capacitance must be considered in the oscillation analysis. • Participation factor analysis is carried out to determine main influencing factors. • A reduced-order model suitable for high-frequency oscillation analysis is proposed. • AC voltage control of MMC has significant effects on the high-frequency oscillation. [ABSTRACT FROM AUTHOR]

NdFeO 3 (NFO) was synthesized using sol-gel citrate method and subsequent calcination at 1023 K. Utilizing Rietveld refinement analysis of the XRD pattern, it has been verified that NFO exhibits an orthorhombic crystal structure, with space group Pbnm. NFO grains were seen to be strongly agglomerated in a SEM image, despite their irregular shapes. The analysis of optical properties revealed a transmittance range of ∼20%–∼50% and an optical band gap of 2.15 eV for the NFO material. The dielectric properties of NFO were analyzed with respect to their dependence on frequency and temperature, while the ac electrical conductivity was studied in terms of its frequency variation. The dielectric dispersion behavior of NFO is explained by Maxwell Wagner-type polarization. A negative magneto-dielectric (MD) coupling of −19% and −35% was measured for ε and tan δ at 1 kHz for NFO. Magneto-impedance measurements on NFO showed positive magneto-resistance and both positive and negative magneto-capacitance, suggesting that the grain effect had a substantial role in the material's magnetic properties. These results suggest that NFO is an excellent choice for memory-based electronic devices with an appropriate band gap for optoelectronic applications having a large MD effect. Structural, dielectric properties at high temperature, magneto-dielectric effects, and Nyquist plots for NdFeO 3 nanoparticles synthesized with sol-gel citrate method. [Display omitted] • NdFeO 3 nanoparticles synthesized via sol-gel citrate method. • XRD data and Rietveld refinement identifies orthorhombic phase (Pbnm space group). • NdFeO 3 nanoparticles have a band gap of 2.15 eV and a transmittance of ∼20% to ∼50%. • Dielectric permittivity and dielectric loss show negative magneto-dielectric coupling. • NdFeO 3 show enhanced magneto-impedance characteristics using Nyquist plots. [ABSTRACT FROM AUTHOR]

The sodium niobate-based ceramics 0.98[(Na (1−x)/2 Sm x/2 Nb 0.3 TiO 3)] + 0.02MnO 2 acronymed NS m NT of different compositions (x = 0.05, 0.1, 0.11, 0.12, and 0.13) were prepared via solid-state reaction method. The prepared samples were characterized by XRD to study the phase structure of the designed systems, SEM to study the microstructure properties of the NS m NT ceramics. In addition to that LCR meter was used to measure the sample temperature-dependent dielectric permittivity, dielectric loss, and systems impedance. The results showed an increment in the dielectric breakdown strength (DBS) with increasing x content from 100 kVcm–1 to 450 kVcm–1. Similarly, the high recoverable energy density (W rec) of 5.61 J cm–3 was obtained for x = 0.11 symbolized (NS m NT2) with an exquisite efficiency of 88%. The study also analyzed the complex impedance of the NS m NT2 ceramics system to clearly understand the dielectric behavior of the system in question. A general view of things considers the NS m NT2 ceramic system to be a reliable system for pulsed power applications. [ABSTRACT FROM AUTHOR]

The main characteristic of liquid crystals is that their properties, both electrical and optical, can be modified through a convenient applied signal, for instance a certain voltage. This tunable behavior of liquid crystals is directly related to the orientation of their nanometric components with respect to a director direction. However, the initial alignment is a fabrication-dependent parameter and may be either planar or homeotropic. In addition, the strong dependence of the properties of liquid crystals with the temperature is well known and widely used for several temperature sensors. This dependence is produced by the influence of the temperature on the ordering of the molecules. In this work, we have studied the temperature dependence of the electric properties of a liquid crystal cell, in particular the dielectric permittivity, with the temperature as a function of the initial alignment set during the fabrication process. Starting from experimental measurements, an equivalent circuit model including the temperature dependence has been proposed. We have observed that a good linearity in a wide temperature range is provided at a suitable exciting frequency. Finally, a proper conditioner circuit is proposed as a powerful tool for linear and high sensibility temperature measurement.

We present a small, compact and portable device for point-of-care instantaneous early detection of anemia. The method used is based on direct hematocrit measurement from whole blood samples by means of impedance analysis. This device consists of a custom electronic instrumentation and a plug-and-play disposable sensor. The designed electronics rely on straightforward standards for low power consumption, resulting in a robust and low consumption device making it completely mobile with a long battery life. Another approach could be powering the system based on other solutions like indoor solar cells, or applying energy-harvesting solutions in order to remove the batteries. The sensing system is based on a disposable low-cost label-free three gold electrode commercial sensor for 50 µL blood samples. The device capability for anemia detection has been validated through 24 blood samples, obtained from four hospitalized patients at Hospital Clínic. As a result, the response, effectiveness and robustness of the portable point-of-care device to detect anemia has been proved with an accuracy error of 2.83% and a mean coefficient of variation of 2.57% without any particular case above 5%.

Arthrospira platensis, commercially known as Spirulina, is a fresh-water cyanobacterium that has been gaining increasing attention in recent years due to its high biological and nutritional value. For this reason, it has been employed in several food applications, to obtain or enhance functional and technological properties of cheese, yogurt, bread, cookies or pasta. The aim of this work was to evaluate the potential boosting effect of two different concentrations (0.25% and 0.50% w/v) of A. platensis on the fermentation capability of several starter lactic acid bacteria (LAB) strains, 1 probiotic and 4 commercial mix culture. These strains were used to ferment three different substrates and their fermentation behaviors were evaluated by impedance analyses together with rheological and color measurements. In tryptic soy broth (TSB), the A. platensis boosting effect was significantly higher if compared to yeast extract for all the starter LAB strains except for Lb. casei, which was equally stimulated. Different results were found when the same LAB strains were cultivated in SSM. The most evident boosting effect was found for S. thermophilus and Lb. casei. LAB growth was promoted by A. platensis, confirming that it could be a useful tool in the production of novel functional fermented dairy foods. The potential boosting effect was evaluated on four commercial mix cultures used to produce milk and soy fermented beverages. It was demonstrated that the booster effect took place, but it was variable and dependent not only on the mix culture used, but also on the substrate and A. platensis concentration. Also, rheological and color modifications were found to be dependent on these factors.

Autochthonous lactic acid bacteria (LAB) play a key role in the development of cheese flavor. As the pasteurization treatment on raw milk causes the elimination of LAB, secondary starter cultures are used in cheese manufacture to obtain cheeses with improved and standardized flavors. In this work, strains of the L. casei group isolated from traditional Italian cheeses were screened for their phenotypic features of technological interest for use as secondary starters. Their milk acidifying performance and the production of volatile compounds when grown in milk were evaluated. Simultaneously, the acetoin metabolic pathway presence was screened in the strains and assessed for its transcriptional activation. The results showed that the analyzed strains, despite belonging to taxonomically-related species, vary greatly according to the measured phenotypes. Four strains among the fourteen screened could be potentially used as adjunct cultures for cheese-making processes. The strain that showed the highest production of acetoin upregulated the aspartate pathway. An increased knowledge of volatile compounds’ production and acidifying properties of LAB strains isolated from traditional dairy products might guide the selection of strains for industrial applications.

Label-free immunosensors are well suited for detection of microorganisms because of their fast response and reasonable sensitivity comparable to infection doses of common pathogens. Active (lever oscillator and frequency counter) and passive (impedance analyzer) modes of quartz crystal microbalance (QCM) were used and compared for rapid detection of three strains of E. coli. Different approaches for antibody immobilization were compared, the immobilization of reduced antibody using Sulfo‑SMCC was most effective achieving the limit of detection (LOD) 8 × 104 CFU·mL−1 in 10 min. For the passive mode, software evaluating impedance characteristics in real-time was developed and used. Almost the same results were achieved using both active and passive modes confirming that the sensor properties are not limited by the frequency evaluation method but mainly by affinity of the antibody. Furthermore, reference measurements were done using surface plasmon resonance. Effect of condition of cells on signal was observed showing that cells ruptured by ultrasonication provided slightly higher signal changes than intact microbes.

This paper develops step-by-step a complete electric model of a light hybrid electric vehicle propulsion system. This model includes the vehicle mass, the radius and mass of the wheels, the aerodynamic profile of the vehicle, the electric motor and the motor drive, among other elements. Each element of the model is represented by a set of equations, which lead to getting an equivalent electric circuit. Based on this model, the outer and inner loop compensators of the motor drive control circuit are designed to provide stability and a fast dynamic response to the system. To achieve this, the steady-state equations and the small-signal model of the equivalent electric circuit are also obtained. Furthermore, as these elements are the main load of the power distribution system of the fully electric and light hybrid electric vehicle, the input impedance model of the set composed of the input filter, the motor drive, the motor, and the vehicle is presented. This input impedance is especially useful to get the system stability of the entire power distribution system.

This work presents the synthesis of PANI-PVA-ZnS nanocomposite films by gamma irradiation approach. The samples were irradiated with different doses ranging from 10 kGy to 40 kGy. Subsequently, structural, morphological, optical and electrical characteristics of the samples were investigated. Fourier transform infrared (FT-IR) spectroscopy was employed to study the chemical structure of the samples. Field emission scanning electron microscopy (FE-SEM) was used to investigate the morphology of nanocomposites. The electronic absorption characteristics of the samples were measured by means of UV-Vis spectroscopy. The AC and DC electrical behaviors of the samples were characterized using LCR meter in the frequency range of 20 Hz to 1 MHz. The impedance values of the samples were extracted from Cole-Cole plots and consequently DC conductivity was calculated. [ABSTRACT FROM AUTHOR]

For the purposes of estimation and control of the vibration amplitude in rotary ultrasonic machining, the relation between vibration amplitude and excitation signal was examined. The mechanical components outside the Terfenol-D were regarded as a single-degree-of-freedom mass spring damping system, and an equivalent mechanical model of the giant magnetostrictive ultrasonic processing system was addressed. After that, the vibration amplitude was modeled as a function of the frequency and amplitude of the excitation current by considering both magnetization and magnetostriction of Terfenol-D and ultimately achieved through parameter identification using the methods of impedance analysis and nonlinear least-squares fitting. In addition, the relation between resonant frequency of the giant magnetostrictive ultrasonic processing system and the magnitude of the excitation current was studied so that the vibration amplitude model was improved. Thus, the vibration amplitude of the giant magnetostrictive ultrasonic processing system excited by various electric signals with different frequencies and amplitudes can be calculated. As demonstrated by comparison with experimental results, the vibration amplitude model can accurately estimate the vibration amplitude of the giant magnetostrictive ultrasonic processing system. It indicates that the model is meaningful for the design and control of the giant magnetostrictive ultrasonic processing system. [ABSTRACT FROM AUTHOR]

NiO x nanostructures are employed to modify the nanoporous TiO 2 photoanode for dye-sensitized solar cells with the surface sol-gel process by multiple spin coating. X-ray photoelectron spectroscopy confirms that the chemical states for the as-prepared NiO x nanostructures are more diverse than those derived by magnetron sputtering. Combined with SEM-EDX results, the structure of NiO x layer cannot be interpreted a uniform “thin film”, but as incomplete coating with a few particulate nickel oxides. The results of dark current measurement and electrochemical impedance spectroscopy analysis suggest that an energy barrier is formed at the interface of electrode and electrolyte by the coated NiO x layers. The basic NiO x -coated surface favors dye attachment, leading to a dramatic enhancement in the amount of adsorbed dye onto the TiO 2 surface. It also demonstrates that an energy conversion efficiency of 6.64% could be achieved for the NiO x -coated TiO 2 electrode with three spin-coated layers of NiO x which accounts for a 27% increment in energy conversion efficiency over that for the unmodified TiO 2 electrode. [ABSTRACT FROM AUTHOR]

The BaCe 0.7 Zr 0.1 Y 0.2−x Zn x O 3−δ (x = 0.05, 0.10, 0.15, 0.20) has been synthesized by the conventional solid state reaction method for application in protonic solid oxide fuel cell. The phase purity and lattice parameters of the materials have been studied by the room temperature X-ray diffraction (XRD). Scanning electron microscopy (SEM) has been done for check the morphology and grain growth of the samples. The chemical and mechanical stabilities have been done using thermogravimetric analysis (TGA) in pure CO 2 environment and thermomechanical analysis (TMA) in Argon atmosphere. The XRD of the materials show the orthorhombic crystal symmetry with Pbnm space group. The SEM images of the pellets show that the samples sintered at 1200 °C are highly dense. The XRD after TGA in CO 2 and thermal expansion measurements confirm the stability. The particles of the samples are in micrometer ranges and increasing Zn content decreases the size. The conductivity measurements have been done in 5% H 2 with Ar in dry and wet atmospheres. All the materials show high proton conductivity in the intermediate temperature range (400–700 °C). The maximum proton conductivity was found to be 1.0 × 10 −2 S cm −1 at 700 °C in wet atmosphere for x = 0.10. From our study, 10 wt % of Zn seems to be optimum at the B-site of the perovskite structure. All the properties studied here suggest it can be a promising candidate of electrolyte for IT-SOFCs. [ABSTRACT FROM AUTHOR]

Conventional solid-state method was used to prepare powders of pure and barium titanate (BT) doped with different concentration of samarium. Influence of samarium addition on the structure modification, grain growth inhibition and microstructure development was studied. Dielectric properties of doped samples were significantly modified. With doping, a diffuse kind of ferro-para phase transition was induced, phase transitions positions were shifted and dielectric permittivity values were lowered in comparison with pure barium titanate. Detailed impedance and modulus data analysis were presented. The impedance complex plane showed two semicircular arcs for pure BT and one single depressed semicircular arc for all doped ceramics. Different electro-active regions in the modulus plane plots were also distinguish. The comparison between impedance and modulus scaling behavior presented the localized movement of charge carriers in the pure barium titanate and both, short and long range relaxations in the ceramics doped with 0.05 mol% of Sm. P-E hysteresis loops have shown the dilution of ferroelectric properties with Sm doping. [ABSTRACT FROM AUTHOR]

Novel proton conducting biopolymer Tamarind Seed Polysaccharide complexed with different concentrations of ammonium bromide have been prepared and characterized. The increase in amorphous nature of the sample has been confirmed by structural analysis. The complex formation between biopolymer and salt has been confirmed by vibrational analysis. The glass transition temperature values of the biopolymer membranes have been found by Differential Scanning Calorimetry analysis. The maximum ionic conductivity 1.58 × 10 −3 S cm −1 is observed for 1 g TSP: 0.4 g NH 4 Br by impedance analysis. The conducting ions in the polymer network have been confirmed by transference number measurement. A simple battery has been fabricated with good stability of 1.54 V as open circuit voltage. The red light emitting diode has been activated by the battery constructed with the highest ionic conductivity membrane. [ABSTRACT FROM AUTHOR]

The X-ray powder analysis, thermogravimetric analysis, differential scanning calorimetry analysis, solid CP-MAS 13 C NMR characterization, vibrational spectroscopy and complex impedance spectroscopic data have been carried out on (C 7 H 10 NO)SnCl 3 compound. The results show that this compound exhibits a phase transition at 314 K which was characterized by 1 H NMR between 298 and 336 K, differential scanning calorimetry (DSC), X-rays powder diffraction, Raman spectroscopy and dielectric measurements. The temperature dependence of the 1 H NMR spectrum for (C 7 H 10 NO)SnCl 3 could be explained by invoking reorientation of ammonium group of the 2-methoxyanilinium cation. The most important changes are observed for two lines at 3087 cm −1 and 3175 cm −1 (at room temperature) issued from asymmetric and symmetric stretching vibrations of ν s(NH3) and ν as(NH3) band, respectively. AC and DC conductivities, complex dielectric permittivity ε*(ω) and complex electrical modulus M*(ω) were respectively studied as temperature and frequency functions. Moreover, the temperature dependence of the DC conductivity and relaxation frequency followed the Arrhenius relation. The frequency dependence of the real part of the AC conductivity in both phases follows the Jonscher's universal dynamic law: σ Tot .(ω,T) = σ DC (T) + B(T) ω S(T) . The close values of activation energies, obtained from the thermal behavior of the conductivity and the relaxation time confirm that the transport is through ion-hopping mechanism. [ABSTRACT FROM AUTHOR]

Sandwiched piezoelectric transducers are widely used, especially in high power applications. For more convenient analysis and design, a PSpice lossy model of sandwiched piezoelectric ultrasonic transducers in longitudinal vibration is proposed by means of the one-dimensional wave and transmission line theories. With the proposed model, the resonance and antiresonance frequencies are obtained, and it is shown that the simulations and measurements have good consistency. For the purpose of further verification the accuracy and application of the PSpice model, a pitch-catch setup and an experimental platform are built. They include two sandwiched piezoelectric ultrasonic transducers and two aluminum cylinders whose lengths are 20 mm and 100 mm respectively. Based on this pitch-catch setup, the impedance and transient analysis are performed. Compared with the measured results, it is shown that the simulated results have good consistency. In addition, the conclusion can be drawn that the optimal excitation frequency for the pitch-catch setup is not necessarily the resonance frequency of ultrasonic transducers, because the resonance frequency is obtained under no load. The proposed PSpice model of the sandwiched piezoelectric transducer is more conveniently applied to combine with other circuits such as driving circuits, filters, amplifiers, and so on. [ABSTRACT FROM AUTHOR]

Nanosized Co 1−x Zn x Fe 2−y Nd y O 4 ferrites with x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0; y=0.0 and 0.1 were synthesized by solution combustion method. All the compositions have been characterized by XRD, SEM technique and irradiated by γ–rays of 60 Co source. Dielectric constant, dielectric loss tangent, ac conductivity and complex impedance are studied in the frequency range 100 kHz–10 MHz for pristine and irradiated composition. The X-ray diffraction patterns revealed the spinel cubic structure. The lattice parameter has increased with increasing Zn 2+ ion concentration. The values of dielectric constant, loss tangent, real and imaginary parts of impedance have been decreased while ac conductivity increased with increasing frequency. The dielectric parameters and ac conductivity were found to increase and attain maximum at x=0.4; y=0.0, x=0.6; y=0.10 and beyond that decreased for further substitution of Zn 2+ ion concentration. The lattice parameter and dielectric parameters were significantly reduced with Nd 3+ ion substitution and increased after γ-irradiation attributed to the conversion of ferric ions to ferrous due to ionizing effect of γ -radiation. Nyquist plots revealed existence of multiple electrical responses. [ABSTRACT FROM AUTHOR]

Research and development activities on sodium-ion batteries are becoming prominent in the past few years. Compared to lithium-based batteries, the sodium-based batteries will be cheaper because of the abundancy of sodium raw materials in the earth's crust and also in seawater. In the current study, we synthesized and characterized poly-acrylonitrile (PAN)-based gel-polymer electrolytes formed with NaClO and dissolved in ethylene carbonate (EC) and propylene carbonate (PC). By systematically varying the weight ratios of polymer, salt, and the solvents, we obtained an optimum room temperature ionic conductivity of 4.5 mS cm for the composition 11PAN-12NaClO-40EC-37PC (wt.%), which is reasonably good for practical applications. This value of conductivity is comparable to a few other Na ion conducting gel-polymer electrolyte systems studied in the recent past. Variation of ionic conductivity with inverse temperature showed Arrhenius behavior. Activation energies estimated for all the samples showed only a slight variation suggesting that a single activation process which depends on the EC/PC co-solvent governs the ionic mobility in these gel-polymer electrolytes. Thermo-gravimetric analysis (TGA) revealed that there is no noticeable weight loss of these electrolytes up to 100 °C and hence the electrolytes are thermally stable for operating temperatures up to 100 °C. [ABSTRACT FROM AUTHOR]

The present work mainly focuses on the preparation of magnesium-doped nickel ferrite nanoparticles via hydrothermal technique. Diffraction pattern attributes the formation of pure cubic spinel phases after microwave heating the samples at 500 °C for 10 min. In addition to the diffraction study, the removal of lepidocrocite (γ-FeO (OH)) signal in an infrared spectrum also confirms the phase purity due to microwave heating. Larger optical band gap (Eg) values are acquired for nanostructures varying between 1.73 and 1.86 eV. The surface morphology is analyzed using transmission electron microscope. The obtained particle sizes are in the range of ∼50–85 nm. The M-H loop analysis shows that 50% of Mg-dopant in Ni-ferrite system exhibits the highest saturation magnetization ∼191 emu/g. The behavior of complex dielectric modulus is illustrated in the specific frequency range of 100 Hz to 5 MHz for investigating the space charge polarization mechanism. [ABSTRACT FROM PUBLISHER]

Layered hexagonal structure Li 1+x (Ni 0.33 Co 0.33 Mn 0.33 )O 2 (LNCM) (x = 0, 0.05, 0.1, 0.15 and 0.2 mol%) compounds were prepared by microwave assisted solvothermal method at two different calcination temperature of 850 and 950 °C. The phase purity of the LNCM compounds was confirmed by Rietveld refined XRD pattern, Raman, and HRTEM studies. The average particle sizes were in the submicron range as confirmed by SEM and TEM analysis. Galvanostatic cycling studies were made in various voltage range, 2.5 to 4.4/4.6/4.8 V at a current rate of 0.2 C. Among all the compounds, LNCM prepared at 950 °C (HS3) exhibited an initial discharge capacity of 197 mAh/g and maintained a capacity of 180 mAh/g at the end of 40 th cycle in 2.5–4.6 V window, indicating an excellent capacity retention. HS3 shows the electrical conductivity of 9.31 × 10 −6 S/cm, which was higher than all the other compounds and discussed the reason for the improved electrochemical performance. [ABSTRACT FROM AUTHOR]

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In this study, Ni 3 S 2 -nanorod and CoNi 2 S 4 -microflower structures have been prepared using a simple one-step hydrothermal method. The complete absence of an additive polymeric binder enabled the electrode to obtain structural purity and excellent electrochemical activity. The formation of the nanorod and micro flowers (µflowers) was clearly visualized by the surface microstructural study. Ni 3 S 2 -nanorod and CoNi 2 S 4 -µflower electrodes show a significantly higher specific capacitance of 982.9 F g −1 and 2098.95 F g −1 , respectively, with outstanding electrochemical cyclic stability performance. The CoNi 2 S 4 -µflower electrode can achieve an energy density of 82.98 Wh kg −1 with a power density of 9.63 kW kg −1 . In addition, a 91% capacitive retention remains after 2000 cycles at a scan rate of 100 mV s −1 . The designed hybrid asymmetric supercapacitor, based on Ni 3 S 2 -nanorod//CoNi 2 S 4 -µflower electrodes, exhibits a specific capacitance of 54.92 F g −1 at a scan rate of 5 mV s −1 . The assembled asymmetric supercapacitor has an energy density of 6.6 Wh kg −1 while delivering a power density of 820 W kg −1 . The capacitive retention of the initial capacitance remains desirable at 89.13% after 5000 CV cycles at a scan rate of 100 mV s −1 . The present work manifests a vision for the fabrication of self-assembled, binder-free electrodes for high-performance hybrid supercapacitor application. [ABSTRACT FROM AUTHOR]

In this paper, a transparent all-solid-state battery was manufactured by RF magnetron sputter, for the first time. LiFePO 4 and Li 4 Ti 5 O 12 are popular cathode and anode materials, respectively. For the solid-state electrolyte coating, the Li 3 PO 4 material is also promising solid electrolyte materials due to the high ionic conductivity. The stack structure of the battery was silver paste/anode ( Li 4 Ti 5 O 12 ) /electrolyte ( Li 3 PO 4 ) /cathode ( LiFePO 4 ) /ITO/glass . An indium tin oxide (ITO) coated glass substrate was used as a transparent and conductive material. The resistance of the coated ITO layer is 40 Ω. RF power for the LiFePO 4, Li 3 PO 4, and Li 4 Ti 5 O 12 layers deposition process was adjusted to 100 Watt at argon atmosphere. This stack structure didn't contain any liquid or gel electrolyte layer. The fully solid electrolyte was deposited by the RF magnetron sputter. The mean crystallite sizes of the deposited layers approximately 30 nm, 21 nm and 30 nm for LiFePO 4 , Li 3 PO 4 and Li 4 Ti 5 O 12 layer, respectively. The transparency of the manufactured battery is approximately 80%. Electrochemical impedance analyses and cyclic voltammetry measurements were done. The Nyquist diagram and equivalent circuit model were determined. Warburg constant and Li-ion diffusion coefficient were calculated approximately 38 Ω/s −1/2 and 4.2 × 10 −10 cm 2 /s, respectively. The capacity of the transparent all-solid-state battery was measured as to be 600 μAh/g. The value of the According to obtained results, deposited battery is a quasi-reversible system because of the differences between cathodic and anodic peak potential is calculated about 52 mV. Warburg, Li-ion diffusion coefficient and capacity of the deposited battery show very good adherence with literature. [ABSTRACT FROM AUTHOR]

The application of the batch injection analysis coupled with multiple-pulse amperometric (BIA-MPA) detection is proposed as an alternative method to obtain the kinetic parameters for simple redox reactions (e.g., Fe(CN) 6 3−/4− , Ru(NH 3 ) 3+/2+ and Fe(H 2 O) 6 3+/2+ ) from analysis of the Tafel plot (TP). The kinetic studies were performed to permit the ‘in situ’ surface characterisation of thin, boron-doped diamond (BDD) films that exhibit a high conductivity. The evaluation of the apparent equilibrium electrode potential ( E eq ) and the kinetic parameters comprising the exchange current ( i 0 ), the anodic and cathodic charge-transfer coefficients (α a and α c ), as well as the apparent heterogeneous rate constant ( k o ), were evaluated through the analysis of the Tafel plots. According to the experimental values of k o , the degree of reversibility strongly depends on the particular redox reaction occurring on the surface of BDD. The k o values obtained for the different redox reactions from analysis of the Tafel plot were compared with those obtained using the electrochemical impedance spectroscopy (EIS) technique. A good agreement for the kinetic parameters determined for the different redox reactions using different experimental approaches (TP and EIS) was obtained through the statistical analysis based on the standard deviation obtained for the different k o values, after five different measurements for each redox reaction. The use of the proposed alternative method for the study of simple electrode reactions can be very helpful because these reactions are often used as a ‘probe’ for the ‘in situ’ surface characterisation of new electrode materials developed for different purposes. [ABSTRACT FROM AUTHOR]

Parathyroid hormone (PTH), a pleiotropic hormone that maintains mineral homeostasis, is also essential for controlling pH balance and ion transport across renal and intestinal epithelia. Optimization of luminal pH is important for absorption of trace elements, e.g., calcium and phosphorus. We have previously demonstrated that PTH rapidly stimulated electrogenic HCO3 secretion in intestinal epithelial-like Caco-2 monolayers, but the underlying cellular mechanism, contributions of other ions, particularly Cl– and K+, and long-lasting responses are not completely understood. Herein, PTH and forskolin were confirmed to induce anion secretion, which peaked within 1–3 min (early phase), followed by an abrupt decay and plateau that lasted for 60 min (late phase). In both early and late phases, apical membrane capacitance was increased with a decrease in basolateral capacitance after PTH or forskolin exposure. PTH also induced a transient increase in apical conductance with a long-lasting decrease in basolateral conductance. Anion secretion in both phases was reduced under HCO3 -free and/or Cl-free conditions or after exposure to carbonic anhydrase inhibitor (acetazolamide), CFTR inhibitor (CFTRinh-172), Na+/H+exchanger (NHE)-3 inhibitor (tenapanor), or K+ channel inhibitors (BaCl2, clotrimazole, and TRAM-34; basolateral side), the latter of which suggested that PTH action was dependent on basolateral K recycling. Furthermore, early- and late-phase responses to PTH were diminished by inhibitors of PI3K (wortmannin and LY-294002) and PKA (PKI 14 –22). In conclusion, PTH requires NHE3 and basolateral K+ channels to induce HCO3 and Cl secretion, thus explaining how PTH regulated luminal pH balance and pH-dependent absorption of trace minerals. [ABSTRACT FROM AUTHOR]

Single-phase Aurivillius Sm 0.5 Bi 4.5 Ti 3 FeO 15 ceramics was synthesized by the conventional solid-state reaction technique. Dielectric response and electrical properties of the ceramics were investigated in a wide range of temperature and frequency by dielectric and impedance spectroscopies. Two dielectric relaxation behaviors were distinguished by the combination of impedance and electric modulus analysis which could be attributed to the contributions of grains and grain boundaries, respectively. The resistance of grain boundaries was found to be much larger than that of grains, whereas the capacitances were in the same level. A ferroelectric phase transition was observed to take place at ∼440 °C. The kinetic analysis was performed to study the corresponding relaxation-conduction mechanisms in the material. Above 270 °C the conduction behavior of the compound was ascribed to the motion of ionized oxygen vacancies. [ABSTRACT FROM AUTHOR]

Conventional 24-h pH monitoring is the gold standard for the diagnosis of non-erosive, non-acidic gastro-esophageal reflux disease. Multichannel Intraluminal Impedance (MII) analysis markedly improves diagnostic accuracy of non-erosive, non-acidic gastro-esophageal reflux disease. However, MII catheters are more expensive than standard catheters. This study aimed to determine the rates of acid or non-acid reflux and by making a retrospective projection, to predict the costs of two algorithms. We retrospectively reviewed the medical data of 102 patients who presented to our hospital with suspected non-erosive GERD and underwent 24 h impedance/pH-monitoring. Demographic characteristics, Demeester scores, number of reflux episodes, and results of impedance analysis were recorded. According to these data, cost was calculated either for the scenario in which impedance measurement was performed solely or following a negative conventional pH monitoring. Thirty-seven of all 102 patients (36.3 %) had a Demeester score greater than 14.7. These patients were assigned as group 1 (acid reflux). The impedance analysis of the remaining 65 patients detected 34 patients (33.3 %) to have more than 50 reflux episodes over a period of 24 h and assigned as Group 2, and 31 patients (30.4 %) had no reflux (group 3). The cost of the single- step algorithm using MII catheter was calculated as $15,300, while the total cost of two-step scenario would have been predicted as $16,890. Our study showed that an initial conventional pH monitoring can make the diagnosis of GERD in only one third of the patients with suspected non-erosive GERD. In nearly two-thirds of patients, however, repeated procedures and use of impedance catheters are needed. It is clear that this algorithm has certain drawbacks with regard to cost, patient comfort, and workforce loss [ABSTRACT FROM AUTHOR]

Resonance and harmonic phenomena can occur when HVDC and Flexible Alternating Current Transmission System devices are inserted into ac grids. Frequency response analysis and electromagnetic transient (EMT) type simulations of converter stations are essential for analyzing and preventing negative effects. This paper presents two approaches for deriving the high frequency response of a converter station: using simplified analytical representation and accurate EMT-type model. Validations with control parameter impacts are presented. This paper also presents a test case, based on a recent HVdc project, where potential resonances can occur between the converter station and its ac network. It is demonstrated analytically that these resonances are mainly due to control system parameters and ac network configurations. [ABSTRACT FROM PUBLISHER]

For resolving deficiencies of conventional tension measurement methods, this paper proposes a novel eddy current sensor with a single-coil structure based on the inverse magnetostrictive effect. An inductor-resistor-capacitor (LRC) model of eddy current sensor, which considers more parameters than the traditional inductor-resistor (LR) model, was established. The eddy current sensor was operated by a swept frequency signal that ranged from 0.1 MHz to 1.6 MHz, encompassing the sensor resonant frequency. At the resonant frequency, the data of impedance magnitude and phase were extracted and linear relations between the impedance parameters and the external tension were ascertained. The experimental results show that the resonant frequency and impedance magnitude of eddy current sensor will decrease linearly with the increase of the external tension, which is consistent with the theoretical model. In addition, to improve sensor performance, the sleeve structure was designed to reduce the loss of magnetic field. Both finite element simulations and experimental results demonstrate that the sleeve structure provides a higher permeability path to the magnetic field lines than the non-sleeve structure and effectively improves sensor sensitivity and correlation coefficient. [ABSTRACT FROM AUTHOR]

The transport properties of lithium-ion conducting LiLaTiO are studied for bulk and grain-boundary effects. This paper introduces a procedure for investigating bulk and grain-boundary polarization contributions using electrochemical impedance spectroscopy (EIS) and subsequent analysis via the distribution function of relaxation times (DRT) [1]. The frequency range of impedance spectroscopy is extended up to 120 MHz to resolve all conductivity contributions occurring in a polycrystalline solid electrolyte. Intra grain (bulk) and inter grain (grain boundary) conductivity contributions are separated using (i) a systematic variation of solid electrolyte contacting, (ii) two different solid electrolyte microstructures and activation energies were determined using adequate equivalent circuit models. Finally, these results are supported by SEM analysis, revealing different grain size distributions and different contents of inhomogeneities in LiLaTiO solid electrolytes sintered at 1400°C and at 1450°C. [ABSTRACT FROM AUTHOR]

A new approach for using quartz resonator (QR) with asymmetrical electrodes for proximity detection has been proposed. This approach takes advantage of the sensitive ability of QR to external electric stimulus. The proximal detecting target disturbs the fringing electric field generated near the electrodes of QR, and changes the series and parallel resonance frequencies of QR. Our experimental results indicate that the parallel resonance frequency is more suitable to be used as a measure parameter, and the detection sensitivity can be significantly enhanced by using an asymmetrical electrodes configuration. The proximity detection sensitivity of the ‘5-3′ QR is about 8 times larger than that of the traditional ‘5-5′ QR. More interesting, we found that the detection sensitivity enhancement of QR using the asymmetrical electrodes configuration does not weaken the stability of the QR. Meanwhile, the influence of physicochemical properties of the detecting targets on the proximity sensing properties of QR has also been studied. This approach provides simple and cost-effective method to achieve proximity detection. [ABSTRACT FROM AUTHOR]

The results of a systematic experimental campaign to verify the impact of real operating conditions on the performance of a complete Molten Carbonate Fuel Cell (MCFC) are presented. In particular, the effects of ageing and composition of water, oxygen and carbon dioxide in the cathodic feeding stream are studied through the analysis of current-voltage curves and Electrochemical Impedance Spectroscopy (EIS). Based on a proposed equivalent electrical circuit model and a fitting procedure, a correlation is found among specific operating parameters and single EIS coefficients. The obtained results suggest a new performance monitoring approach to be applied to MCFC for diagnostic purpose. Particular attention is devoted to operating conditions characteristic of MCFC application as CO 2 concentrators, which, by feeding the cathode with exhaust gases, is a promising route for efficient and cheap carbon capture. [ABSTRACT FROM AUTHOR]

• The novel semiconducting Tamarind seed polysaccharide (TSP) was mixed with sodium acetate to get biopolymer electrolyte films by solution cast technique for application in green energy devices. • The conductivity of 80:20 ratio films was found to be higher and it was 1.95 × 10−4 s cm−1 at room temperature which was three orders higher than pure TSP polymer. • The conductivity rises with increasing temperature which follows Arrhenius behaviour. • Dielectric studies were done by AC impedance spectroscopy and transportation numbers were calculated using Wagner's polarisation technique. • Discharge studies of the cell showed good stability and performance with OCV at 1.68 V and SCC at 0.69 mA. Solid biopolymer electrolytes have gained enormous attention recently due to their potential as non-toxic, biodegradable properties over their synthetic counterpart. Considering their uses in energy applications, the present investigation aims to synthesize and characterize solid biopolymer electrolytes comprising tamarind seed polysaccharide (TSP) as the host polymer and sodium acetate (CH 3 COONa) salt as the ionic dopant. The solution cast technique was employed to create free-standing tamarind seed polysaccharide (TSP): Sodium acetate (CH 3 COONa) solid polymer electrolyte films with varying weight percentages. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies investigated the structural and chemical correlation between TSP and CH 3 COONa. AC impedance spectroscopy was used to test the conductivity and dielectric properties of the prepared polymer films. The conductivity rises with increasing temperature. The maximum conductivity was found to be 1.95 × 10−4 S cm−1 for 80:20 (TSP: CH 3 COONa) wt.% ratio sample at room temperature (303 K), which was three orders of magnitude higher than the pure TSP (10−7 S cm−1). These polymer electrolyte films showed conductivity that altered with temperature, which follows Arrhenius's behaviour. Dielectric studies showed that dielectric constant and dielectric loss were high at low frequencies and decreased at high frequencies. Wagner's polarisation technique confirmed that charge transport in these polymer electrolyte systems was principally ionic, with the highest t ion (̴ 0.99) and electrons having a negligible contribution. The discharge studies of the cell showed good stability and performance with OCV at 1.68 V and SCC at 0.69 mA. [ABSTRACT FROM AUTHOR]

Dependence of tan δ on temperature. [Display omitted] • Rietveld refinement technique confirms the compound crystallizes with monoclinic symmetry. • The SEM micrograph shows two different types of the material present; a low dense polyhedral grain material and a foamy material, consisting of very small particles. • The isotropy value shows the grain texture and compactness on the surface. • A small tangent loss with high dielectric constant and improved ferroelectric properties. • The decreasing behavior of activation energy suggests the hopping of electrons in the material. • Temperature dependence of resistance yields a negative temperature coefficient of resistance (NTCR) behavior of the compound. In this communication, preliminary investigation of structural and detailed analysis of electrical proprties of a new barium bismuth tungstate of a chemical composition Ba 3 Bi 2 WO 9 , produced via a standard high-temperature solid-state reaction method, is presented. The basic crystal structure of the compound is monoclinic (a = 8.4621 Å, b = 6.7358 Å, c = 6.9064 Å and β = 109.94°). The homogeneous distribution of grains (average grain size = 1.717 μm) is studied via surface morphology demonstrating the feasibility of fabricating a high-density sample under experimental conditions. This compound shows ferroelectric and related properties, which have been experimentally verified by examination of the frequency-temperature dependence of capacitance, impedance, and other related behaviors. The variation of ac conductivity of the material under alternating current varies according to Jonscher's universal power law. The ferroelectric property of the material (Pr = 0.331C/cm2, Ec = 0.207 kV/cm) is demonstrated by the electric field-dependent polarisation (P-E loop) study. The temperature dependence of resistance yields a thermistor constant (β) and temperature coefficient of resistance (TCR), which may be useful for fabricating thermistor-based device applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • (Nd, Cr) co-substitution on BiFeO 3 using solid-state synthesis method, shows distorted rhombohedral (R3c) symmetry characteristic for low concentration doping which gets reduced and then transforms to orthorhombic symmetry. • Co-doping modifies dielectric and electric behaviour because of their structural, microstructural and morphological properties. • Ac conductivity and Impedance analysis suggest the dipole moment nature in the samples. • Low doping concentrations of Nd and Cr in the place of Bi and Fe provide promising results compared to high concentrations due to less distortions and strain induced in the microstructure. Neodymium and Chromium codoped bismuth ferrite samples [Bi 0.8 Nd 0.2 Fe 1-x Cr x O 3 (x = 0.2,0.4,0.6 and 0.8)] are prepared using solid state reaction method. Structural and morphological studies including XRD, FESEM and Raman characterization are carried out as preliminary characterizations. Dielectric studies such as dielectric constant, dielectric loss, and subsequent impedance analysis and ac conductivity measurements with respect to frequency and temperature reveal that lower concentration of dopant have stable results. The electrical properties in connection with the structural and morphological understanding of samples and the nature of dopant element and their concentration have been discussed here. [ABSTRACT FROM AUTHOR]

The sensitivity to cold plasma is specific to tumor cells while leaving normal tissue cells unaffected. This is the desired challenge in cancer therapy. Therefore, the focus of this work was a comparative study concerning the plasma sensitivity of dermal tumor cells (A-431) versus non-tumorigenic dermal cells (HaCaT) regarding their adhesion capacity. We found a selective inhibiting effect of plasma-activated medium on the adhesion of tumor cells while hardly affecting normal cells. We attributed this to a lower basal gene expression for the adhesion-relevant components CD44, hyaluronan synthase 2 (HAS2), HAS3, and the hyaluronidases in A431. Noteworthy, after plasma exposure, we revealed a significantly higher expression and synthesis of the hyaluronan envelope, the HAS3 gene, and the transmembrane adhesion receptors in non-tumorigenic HaCaTs.

Electrical characteristics of living cells have been proven to reveal important details about their internal structure, charge distribution and composition changes in the cell membrane, as well as the extracellular context. An impedance flow cytometry is a common approach to determine the electrical properties of a cell, having the advantage of label-free and high throughput. However, the current techniques are complex and costly for the fabrication process. For that reason, we introduce an integrated dual microneedle-microchannel for single-cell detection and electrical properties extraction. The dual microneedles utilized a commercially available tungsten needle coated with parylene. When a single cell flows through the parallel-facing electrode configuration of the dual microneedle, the electrical impedance at multiple frequencies is measured. The impedance measurement demonstrated the differential of normal red blood cells (RBCs) with three different sizes of microbeads at low and high frequencies, 100 kHz and 2 MHz, respectively. An electrical equivalent circuit model (ECM) was used to determine the unique membrane capacitance of individual cells. The proposed technique demonstrated that the specific membrane capacitance of an RBC is 9.42 mF/m -2 , with the regression coefficients, ρ at 0.9895. As a result, this device may potentially be used in developing countries for low-cost single-cell screening and detection.