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- Dielectric Spectroscopy, Physical sciences, Second Order
- by Marcos A L Nobre
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- Materials Science, Sensors and Sensing, Sintering, High Temperature Ceramics

Dielectric properties of some conducting polymers were investigated and their electrical properties are compared with each other. Temperature dependencies of their electrical properties are investigated throughout the work. Electrical behaviors of the synthesized systems constitute a good infrastructure for both understanding the intrinsic mechanisms and optimizing new synthesizes. It is found that, it can be possible to attain desired electrical properties by small synthesis modulations in thiophene based polymer materials.

- by Vera Lockett
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- Chemistry, Electrochemistry, Carbon, Ionic Liquid

We put forward an impedometric protein-based biosensor platform suitable for point-of-care diagnostics. A hand-held scale impedance reader system is described for the detection of corresponding physiochemical changes as the immobilized... more

- by Mohamad Sawan
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- Materials Engineering, Algorithms, Biomedical Engineering, Protein Engineering

It is shown that only 10% of the 99wt% water present in bacterial cellulose (BC) gels, produced by Acetobacter xylinum, behave like free bulk water; the majority of the water molecules in the gels is more or less tightly bound to the... more

- by Katarina Edwards
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- Engineering, Electron Microscopy, Polymer, Dielectric Spectroscopy

Based on permittivity changes, a new method to measure hematocrit (HCT) in extracorporeal blood systems is presented. Human blood samples were tested at different HCT levels pairing the values of permittivity change, obtained by means of a commercial impedance analyzer, with traditional centrifugation measurements. Data were correlated using both linear and nonlinear regression. When using the lineal model, the comparison

- by Max Valentinuzzi
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- Algorithms, Biomedical Engineering, Spectroscopy, Biomedical

Four series of new [1]benzothieno[3,2- b][1]benzothiophene derivatives have been synthesized. In the non-chiral series a SmA phase occurs, while the chiral series exhibits a rather wide antiferroelectric SmC* phase just below the SmA phase. The SmA-SmC* phase transition has been studied using DSC and dielectric spectroscopy. In the SmC* phase the spontaneous quantities have been measured. The tilt angle shows

- by Juan Vidal
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- Analytical Chemistry, Biomedical Engineering, Fungi, Nanotechnology
- by Karen Cheung
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- Engineering, Flow Cytometry, Lab On A Chip, Dielectric Spectroscopy

Agricultural waste ashes are used as resource materials to synthesize new glass and glass-ceramics. The as-prepared materials are characterized using various techniques for their structural and dielectric properties to check their suitability in microelectronic applications. Sugarcane leaves ash exhibits higher content of alkali metal oxides than rice husk ash, which reduces the melting point of the components due to eutectic reactions. The addition of sugarcane leaves ash in rice husk ash promotes the glass formation. Additionally, it prevents the cristobalite phase formation. These materials are inherently porous, which is responsible for low dielectric permittivity i.e. 9 to 40. The presence of less ordered augite phase enhances the dielectric permittivity as compared to cristobalite and tridymite phases. The present glass-ceramics exhibit lower losses than similar materials synthesized using conventional minerals. The dielectric permittivity is independent to a wide range of tem...

- by B. Sanchez
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- Engineering, Humans, Calibration, Female

Nanograins of SmCoO3 are prepared by citric acid assisted sol-gel autocombustion route. The characterizations of crystal structure, surface morphology and electrical properties of SmCoO3 powder are done using XRD, HRSEM, FTIR and BDS. The structural evolution of SmCoO3 upon increasing the annealing temperature is followed using XRD and FTIR analyses. The powder sample contains polycrystalline grains with average size equal to 35 nm and orthorhombic perovskite structure with Pbnm space group. The vibrational bands observed in FTIR spectrum at 545 cm−1 and 439 cm−1 correspond to Co-O stretching modes in cobaltite system. HRSEM images of the sample show the formation of hexagonal shaped grains of samarium cobaltite. The AC electrical conductivity of 4.914 × 10−5 S cm−1 at 295 K is measured for SmCoO3 nanoparticles. The impedance spectra bring out the semiconducting behavior of the material.

- by Sathyamoorthy B
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- Nanomaterials, Structural Analysis, Perovskites, Dielectric Spectroscopy

Dielectric and electric behaviour of calcite and dolomite aqueous solutions were investigated using dielectric spectroscopy and electric modulus formalism. The electrode polarisation influence was observed in the low-frequency region. The influence of including grain-size (5 µm, 10 µm and 20 µm) concentration (5 × 10−5–10−2 g L−1) and temperature (295–313 K) to dielectric constant, electric modulus and conductivity was established. The Cole–Cole plot showed only one suppressed semicircle with centre below the x-axis, whose diameter changes with the grain diameter size or temperature, confirming one relaxation non-Debye process. The activation energies of conduction processes were calculated. Using the Jonscher power law, we obtained pre-factor A and exponent n.

- by Margareta Pecovska
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- Low Frequency, Classical Physics, Dielectric Spectroscopy, Power Law
- by Rabdel Ruiz-Salvador
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- Chemical Education, Education, Chemical, Dielectric Spectroscopy

� (rGO)/La 0.9 Bi 0.1 FeO 3 (LBFO) nanocomposites were prepared by sol-gel method. � LFBO has a single-phase and were homogeneously dispersed on graphene nanosheets. � rGO improves the electrical properties up to 50 wt% of rGO. � The ferromagnetic behavior was detected and an enhancement of magnetic properties with rGO. � The magnetic and electrical properties can be optimized by tuning the content of rGO. A B S T R A C T Reduced graphene oxide (rGO)/La 0.9 Bi 0.1 FeO 3 (LBFO) nanocomposites were successfully prepared. The structure , morphology, electrical and magnetic properties were investigated by X-ray diffraction, high-resolution transmission electron microscope, impedance analyzer, and vibrating sample magnetometer, respectively. Results show that perovskites LFBO has a single-phase and were homogeneously dispersed on graphene nanosheets. rGO improves the electrical properties up to 50 wt% of rGO. The ferromagnetic behavior of nanocomposites was detected and also an enhancement of its magnetic properties with rGO content. These results reveal that the magnetic and electrical properties can be optimized by tuning the content of rGO.

- by A. M . Mansour
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- Magnetic Materials, Nanocomposites, Perovskites, Dielectric Spectroscopy
- by Paul Ben Ishai
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- Physics, Materials Science, Solid State Physics, Chemistry
- by Rahman Wagiran
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- Analytical Chemistry, Water, Nanocomposites, Sensors
- by Aldo Sihite
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- Dielectric Spectroscopy

Nanocomposites possess different characteristics that could potentially contribute to the technological development in various sector including dental applications, dielectric enhancement, capacitors, drug delivery and many more. In this research study, a nanocomposite is formed between polypropylene (PP) and titanium dioxide (TiO2). TiO2 acts as a filler for the polymer matrix and this addition could significantly improve several properties suitable for its dielectric application. A melt intercalation method is used for the mixing process involving several process units such as rotating twin-screw extruder, pelletizer, dryer and injection molding. The dispersion of nanofiller in the host polymer matrix is identify by using a scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and LCR meter. The microscopic analysis obtained for the nanocomposite shows high dispersion at below than 4 wt.%, which clearly shown by the less agglomeration produced. Similar results is obtained for thermal properties as nanocomposite with lower than 4 wt.% shows better thermal stability and higher onset as well as maximum degradation temperature. Despite lack of studies conducted in dielectric studies of polypropylene (PP)/ titanium dioxide (TiO2) nanocomposite, performance is best considered at 10 wt.% to 20 wt.%. For total, this review paper investigate the blending effect of PP/TiO2 nanocomposite at three distinct properties which is surface morphology, thermal properties and dielectric performances.

- by Wishal Kurnia
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- Polymer Engineering, Chemical Engineering, Polymer Chemistry, Nanocomposites

The lead-free polycrystalline ceramic, barium titanate modified bismuth–sodium titanate 0.98(Bi0.5Na0.5TiO3) + 0.02 BaTiO3
(BNT–BT-2) was synthesized by using a mixed oxide route at high temperature. The structural (crystal structure, microstructure, molecular
structure), and electrical (dielectric constant and loss,
impedance, conductivity) characteristics of the parent compound
(
Bi0.5Na0.5TiO3) have greatly been influenced by the
addition of even a small amount of barium titanate in it.
Preliminary structural study of BNT–BT-2 using X-ray diffraction
data clearly shows the formation of a single-phase
perovskite structure with the coexistence of hexagonal
(major phase) and tetragonal (minor) phases. The existence
of diffuse phase transtition and the relaxor behaviour in the
material is confirmed by analysis of temperature-frequency
dependence of dielectric parameters. The composition
(0.98BNT − 0.02BT) of the material shows non-Ohmic conduction
in its J–E characteristics. In this lead-free ceramic, permittivity anomalies are matched to modulus anomalies.
The highlighted features are determined by structural phase
transitions of the ferroelectric-like.

- by Sugato Hajra
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- Dielectric Spectroscopy, XRD Crystallography
- by Ivo Petrov
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- Biomaterials, Tissue Engineering, Chitosan, Regenerative Medicine
- by Khelifi Hedi
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- Particle Physics, Astronomy, Ceramics, Dielectric Spectroscopy
- by Garret Moddel
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- Physics, Nonlinear Optics, Electronics, Liquid Crystals

- by Wishal Kurnia
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- Polymer Engineering, Chemical Engineering, Polymer Chemistry, Nanocomposites
- by Juras Banys and +1
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- Materials Engineering, Chemical Engineering, Low Frequency, Manufacturing Engineering
- by Brandon Rowe
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- Engineering, Polymer, Dielectric Spectroscopy, Motion processing
- by Parham Hashemzadeh and +2
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- Bioinformatics, Inverse Problems, Tomography, Humans

The structural, vibrational, magnetic and dielectric properties of polycrystalline BiFeO3 and Bi0.95Pr0.05FeO3 are investigated by combining X-ray diffraction, Raman scattering spectra, magnetometry and dielectric measurements. Structural symmetry with rhombohedral R3c phase is revealed for both parent and 5% Pr substitution at Bi site, serving no chemical pressure and causes no structural transition from R3c to any other phase is identified from x-ray diffraction patterns and Raman scattering spectra. The shifting of phonon modes towards higher frequency side is attributed to lower atomic mass of Pr ion as compared to Bi ion. The magnetic measurements at room temperature indicate that Pr substitution induces ferromagnetism and discerns large and non-zero remnant magnetization as compare to pristine BiFeO3. Both dielectric permittivity and loss factor of Bi0.95Pr0.05FeO3 strongly decreases with increased frequency. Significant role of hopping of oxygen ion vacancies in Bi0.95Pr0.05FeO3 is inferred from modulus spectra and ac conductivity analysis.

Non-destructive systems are recent trends for quality evaluation of fruits and vegetables. Information on post-harvest variations in electrical properties is needed to develop new instruments for this purpose. Electrical properties are finding increasing application in agriculture and food processing industries. Knowledge of dielectric properties of foods as a function of moisture content and temperature is essential in the design and

- by Narayan Jha
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- Food, Food Processing, Food Science and Technology, Food Quality

We critically review the literature on the Debye absorption peak of liquid water and the excess response found on the high frequency side of the Debye peak. We find a lack of agreement on the microscopic phenomena underlying both of these features. To better understand the molecular origin of Debye peak we ran large scale molecular dynamics simulations and performed several different distance-dependent decompositions of the low frequency dielectric spectra, finding that it involves processes that take place on scales of 1-2 nm. We also calculated the k-dependence of the Debye relaxation, finding it to be highly dispersive. These findings are inconsistent with models that relate Debye relaxation to local processes such as the rotation/translation of molecules after H-bond breaking. We introduce the " spectrumfitter " Python package for fitting dielectric spectra and analyze different ways of fitting the high frequency excess, such as including one or two additional Debye peaks. We propose using the generalized Lydanne-Sachs-Teller (gLST) equation as a way of testing the physicality of model dielectric functions. Our gLST analysis indicates that fitting the excess dielectric response of water with secondary and tertiary Debye relaxations is problematic. We suggest that a distribution of Debye and oscillatory modes or truncated power-law is the correct way to fit the excess response. Our work is consistent with the recent theory of Popov et al. (2016) that Debye relaxation is due to the propagation of Bjerrum-like defects in the hydrogen bond network, similar to the mechanism in ice.

- by Daniel C Elton
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- Spectroscopy, Dielectric Spectroscopy, Dielectric Properties
- by Michele Forina
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- Signal Processing, Pattern Recognition, Food Analysis, Potentiometry

A series of hybrid polyurethane–POSS materials have been synthesized on the basis of poly(tetramethylene glycol) (Terathane 1400®) as soft component, 4,4′-methylenebis(phenylisocyanate) (MDI) as hard component, and 1,4-butanediol as chain extender. POSS particles properly modified have been tethered on the main chain by substitution of the chain extender to weight fractions up to 10%. AFM measurements indicate the formation of POSS crystallites in the PU matrix, extended structures at low POSS content and more regular, smaller structures at higher POSS content. A detailed investigation of molecular mobility by means of Differential Scanning Calorimetry (DSC), Thermally Stimulated Depolarization Currents (TSDC) and, mainly, Broadband Dielectric Relaxation Spectroscopy (DRS) has been conducted in all samples of the series and in addition in neat Terathane, as reference. Four relaxations have been studied in detail: two secondary relaxations γ and β, the segmental α relaxation (dynamic glass transition) and an α′ relaxation slower than α associated with crystallinity in neat Terathane and with the presence of hard microdomains in the polyurethane and the hybrids. Secondary relaxations remain unaffected by POSS. The glass transition temperature rises by a few degrees and, in consistency with that, segmental dynamics slightly slows down with increasing POSS content. In addition, the dielectric strength of the segmental relaxation decreases with increasing POSS content, suggesting that a fraction of polymer is immobilized, making no contribution to the relaxation. These results are discussed in relation to morphology.

- by Chaker Tlili
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- Chemical Engineering, Analytical Chemistry, Electrochemistry, Escherichia coli
- by A. Scheuermann and +1
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- Soil Science, Geotechnical Engineering, Dielectric Spectroscopy, Soil Moisture Sensor

The present volumes form the proceedings of the Third International Conference on Ferroelectric Liquid Crystals, held in Boulder, Colorado, USA 23-28 June 1991. These volumes continue the publication of this conference series, the proceedings of the first conference (1987) held at Bordeaux/Arcachon appearing in Volumes 84 and 85, and the proceedings of the second conference (1989) held at Goteborg appearing in Volumes 113 and 114. As for the two preceding conferences, FLC-91 provided a broad forum for the exchange of information on FLCs, with most of the groups working in the field well represented. Exciting developments were reported in all FLC areas. The worldwide effort at developing new FLC materials continues apace, with the report of an FLC material possessing a spontaneous polarization nearly equal to the sum of all transverse molecular dipoles, and new thrusts in polymer FLCs and FLCs for electronic nonlinear optical applications. The conference saw many new developments in FLC basic and device physics, including the use of dielectric spectroscopy as a tool for studying the molecular origins of the polarization in FLCs. Particularly exciting were the FLC device developments with the emergence of sophisticated FLC devices for opto-electronic computing, display, and other light control applications including a demonstration of a flexible polymer FLC display.

- by Garret Moddel
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- Physics, Nonlinear Optics, Electronics, Liquid Crystals
- by Omar Rosas
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- Bioelectrochemistry, Biofilms, Carbon, Corrosion

Electroporation of cells is successfully used in biology, biotechnology and medicine. Practical problems still arise in the electroporation of cells in suspension. For example, the determination of cell electroporation is still a demanding and time-consuming task. Electric pulses also cause contamination of the solution by the metal released from the electrodes and create local enhancements of the electric field, leading to the occurrence of electrochemical reactions at the electrode/electrolyte interface. In our study, we investigated the possibility of assessing modifications to the cell environment caused by pulsed electric fields using electrochemical impedance spectroscopy. We designed an experimental protocol to elucidate the mechanism by which a pulsed electric field affects the electrode state in relation to different electrolyte conductivities at the interface. The results show that a pulsed electric field affects electrodes and its degree depends on the electrolyte conduct...

- by Bachir Maouche
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- Bioelectrochemistry, Electroporation, Animals, Dielectric Spectroscopy
- by Nader Yourdshahi
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- Engineering, Analytical Chemistry, Bioelectrochemistry, Electrochemistry
- by Peter Ghazal
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- Analytical Chemistry, Biomedical Engineering, Biosensors, Cytokines
- by Imanol Pedro and +2
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- Thermodynamics, Crystallization, Dielectric Spectroscopy, Physical sciences

Due to the interest in protein dynamics, there are numerous dielectric relaxation studies of proteins in water and in glass-forming aqueous solvents such as glycerol-water mixtures. In the regime of low frequencies, the inevitable dc-conductivity of such systems limits the resolution of dynamics that are slow compared with the solvent relaxation. Solutions of myoglobin in glycerol/water mixtures of various compositions are measured by dielectric spectroscopy in the frequency range from 10mHz to 10MHz. The resolution of low frequency modes is improved by two approaches: electrical &amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;cleaning&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; and the analysis of the derivative of the real component of permittivity, which shows no direct signature of dc-conductivity. Effects of internal interfacial polarization are also addressed by measuring the same solvents in confinement as well as mixed with glass beads. We find two processes, the structural relaxation of the solvent and the slower rotational mode of the protein, with no indication at even lower frequencies of a dielectric signature of fluctuations associated with protein dynamics.

- by Soham Roy
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- Thermodynamics, Water, Biological Sciences, Animals