Displaying publications 41 - 60 of 128 in total

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  1. Fulltext The link between airway reflux and non-acid reflux in children: a review
    Saniasiaya J, Kulasegarah J
    Braz J Otorhinolaryngol, 2023;89(2):329-338.
    PMID: 35659765 DOI: 10.1016/j.bjorl.2022.05.002
    OBJECTIVE: Airway reflux, a member of extra-esophageal reflux, has been linked to countless respiratory pathologies amongst children. The advent of novel instrumentation has enabled the discovery of non-acid reflux which was postulated as the main culprit of airway reflux. The objective of this review is to outline the association between non-acid reflux and airway reflux in children.

    METHODS: A comprehensive review of recent literature on non-acid reflux and airway reflux in children was conducted. Studies ranged from January 2010 till November 2021 were searched over a period of a month: December 2021.

    RESULTS: A total of eleven studies were identified. All studies included in this review revealed a strong link between non-acid reflux and airway reflux in children. 6 of the included studies are prospective studies, 3 retrospective studies, 1 cross-section study, and type of study was not mentioned in 1 study. The most common reported respiratory manifestation of non-acid reflux in children was chronic cough (7 studies). Predominant non-acid reflux was noted in 4 studies. The total number of children in each study ranges from 21 to 150 patients. MII-pH study was carried out in all studies included as a diagnostic tool for reflux investigation.

    CONCLUSION: Non-acid reflux is the culprit behind airway reflux as well as other myriads of extra-esophageal manifestations in children. Multicentre international studies with a standardized protocol could improve scientific knowledge in managing non-acid reflux in airway reflux amongst children.

    Matched MeSH terms: Electric Impedance
  2. Fulltext Single-fed broadband CPW-fed circularly polarized implantable antenna for sensing medical applications
    Butt AD, Khan J, Ahmad S, Ghaffar A, Abdullah Al-Gburi AJ, Hussein M
    PLoS One, 2023;18(4):e0280042.
    PMID: 37053176 DOI: 10.1371/journal.pone.0280042
    Biomedical telemetry relies heavily on implantable antennas. Due to this, we have designed and tested a compact, a circularly polarized, a low-profile biomedical implantable antenna that operate in the 2.45 GHz ISM band. In order to keep the antenna compact, modified co-planar waveguide (CPW) technology is used. Slotted rectangular patch with one 45-degree angle slot and truncated little patch on the left end of the ground plane generate a frequency-range antenna with circular polarization. Using a 0.25-millimeter-thick Roger Duroid-RT5880 substrate with a thickness of εr = 2.2, tanδ = 0.0009 provides flexibility. The volume of the antenna is 21 mm x 13.5 mm x 0.254 mm (0.25λg × 0.16λg × 0.003λg). The antenna covers 2.35-2.55 GHz (200 MHz) in free space and 1.63-1.17 GHz (1.17 GHz) in epidermal tissue. With skin tissue that has more bandwidth, the (x and y)-axis bends of the antenna are also simulated via the simulation. Bended antenna simulations and measurements show excellent agreement. At 2.45 GHz, the skin-like gel had -10dB impedance and 3dB axial ratio (AR) bandwidths of 47.7 and 53.8%, respectively. The ultimate result is that the SAR values are 0.78 W/kg in skin over 1 g of bulk tissue, as determined by simulations. The suggested SAR values are lower than the FCC's maximum allowable limit (FCC). This antenna is small enough to be implanted in the body, making it perfect for biomedical applications.
    Matched MeSH terms: Electric Impedance
  3. Fulltext Emerging Roles of the Endolumenal Functional Lumen Imaging Probe in Gastrointestinal Motility Disorders
    Ata-Lawenko RM, Lee YY
    J Neurogastroenterol Motil, 2017 Apr 30;23(2):164-170.
    PMID: 28013295 DOI: 10.5056/jnm16171
    Gastrointestinal sphincters play a vital role in gut function and motility by separating the gut into functional segments. Traditionally, function of sphincters including the esophagogastric junction is studied using endoscopy and manometry. However, due to its dynamic biomechanical properties, data on distensibility and compliance may provide a more accurate representation of the sphincter function. The endolumenal functional lumen imaging probe (EndoFLIP) system uses a multi-detector impedance planimetry system to provide data on tissue distensibility and geometric changes in the sphincter as measured through resistance to volumetric distention with real-time images. With the advent of EndoFLIP studies, esophagogastric junction dysfunction and other disorders of the stomach and bowels may be better evaluated. It may be utilized as a tool in predicting effectiveness of endoscopic and surgical treatments as well as patient outcomes.
    Matched MeSH terms: Electric Impedance
  4. Fulltext The potential of incorporation of binary salts and ionic liquid in P(VP-co-VAc) gel polymer electrolyte in electrochemical and photovoltaic performances
    Ming NH, Ramesh S, Ramesh K
    Sci Rep, 2016 06 08;6:27630.
    PMID: 27273020 DOI: 10.1038/srep27630
    In this study, dye-sensitized solar cells (DSSCs) has been assembled with poly(1-vinylpyrrolidone-co-vinyl acetate) (P(VP-co-VAc)) gel polymer electrolytes (GPEs) which have been incorporated with binary salt and an ionic liquid. The potential of this combination was studied and reported. The binary salt system GPEs was having ionic conductivity and power conversion efficiency (PCE) that could reach up to 1.90 × 10(-3) S cm(-1) and 5.53%, respectively. Interestingly, upon the addition of the ionic liquid, MPII into the binary salt system the ionic conductivity and PCE had risen steadily up to 4.09 × 10(-3) S cm(-1) and 5.94%, respectively. In order to know more about this phenomenon, the electrochemical impedance studies (EIS) of the GPE samples have been done and reported. Fourier transform infrared studies (FTIR) and thermogravimetric analysis (TGA) have also been studied to understand more on the structural and thermal properties of the GPEs. The Nyquist plot and Bodes plot studies have been done in order to understand the electrochemical properties of the GPE based DSSCs and Tafel polarization studies were done to determine the electrocatalytic activity of the GPE samples.
    Matched MeSH terms: Electric Impedance
  5. Fulltext Single Cell Electrical Characterization Techniques
    Mansor MA, Ahmad MR
    Int J Mol Sci, 2015;16(6):12686-712.
    PMID: 26053399 DOI: 10.3390/ijms160612686
    Electrical properties of living cells have been proven to play significant roles in understanding of various biological activities including disease progression both at the cellular and molecular levels. Since two decades ago, many researchers have developed tools to analyze the cell's electrical states especially in single cell analysis (SCA). In depth analysis and more fully described activities of cell differentiation and cancer can only be accomplished with single cell analysis. This growing interest was supported by the emergence of various microfluidic techniques to fulfill high precisions screening, reduced equipment cost and low analysis time for characterization of the single cell's electrical properties, as compared to classical bulky technique. This paper presents a historical review of single cell electrical properties analysis development from classical techniques to recent advances in microfluidic techniques. Technical details of the different microfluidic techniques are highlighted, and the advantages and limitations of various microfluidic devices are discussed.
    Matched MeSH terms: Electric Impedance
  6. Fulltext Effect of shield placement for transient voltage mitigation due to switching surges in a 33/11 kV transformer windings
    Srikanta Murthy A, Azis N, Jasni J, Othman ML, Mohd Yousof MF, Talib MA
    PLoS One, 2020;15(10):e0240368.
    PMID: 33035254 DOI: 10.1371/journal.pone.0240368
    This study presents an investigation on the effect of shield placement for mitigation of transient voltage in a 33/11 kV, 30 MVA transformer due to Standard Switching Impulse (SSI) and Oscillating Switching Impulse (OSI) surges. Generally, the winding and insulation in transformers could experience severe voltage stress due to the external impulses i.e. switching events. Hence, it is important to examine the voltage stress and identify the mitigation action i.e. shield placements in order to reduce the adverse effect to the transformer windings. First, the resistances, inductances, and capacitances (RLC) were calculated for disc type transformer in order to develop the winding RLC equivalent circuit. The SSI and OSI transient voltage waveforms were applied to the High Voltage (HV) winding whereby the transient voltages were simulated for each disc. The resulting voltage stresses were mitigated through different configurations of electrostatic shield placements. The resonant oscillations generated due to switching surges were analysed through initial voltage distribution. The analyses on the transient voltages of the transformer winding and standard error of the slope (SEb) reveal that the location of shield placement has a significant effect on the resonant switching voltages. The increment of the shield number in the windings does not guarantee optimize mitigation of the resonant switching transient voltages. It is found that the voltage stress along the windings is linear once a floating shield is placed between the HV and Low Voltage (LV) windings of the disc-type transformer under the SSI and OSI waveforms. These findings could assist the manufacturers with appropriate technical basis for mitigation of the transformer winding against the external transient switching overvoltage surges.
    Matched MeSH terms: Electric Impedance
  7. Fulltext Bending effects study on flexible wearable antenna for 2.45 GHz body centric wireless communications
    Aslina A. Bakar, Amirul A. Mustafa, Ahmad R. Razali, Norhayati Mutalib, Amirudin Ibrahim
    ESTEEM Academic Journal, 2020;16(2):75-87.
    MyJurnal
    This study aims to investigate the bending effects on the flexible wearable antenna by using copper nanowires and polydimethylsiloxane (PDMS). This project focuses on the bending effect on the proposed wearable antenna in the presence of skin tissue and at free space. The radiation characteristics were simulated and analyzed when the antenna was under flat and bent conditions. The performance result of return loss and radiation pattern (Efield and H-field) of proposed wearable antenna was analyzed. The material for the proposed antenna is designed to be flexible and wearable for the application of body-centric wireless communication (BCWCs) at the frequency of 2.45 GHz with the approval specifications of industrial, scientific and medical (ISM) band. Radiator for the proposed wearable antenna is fabricated using copper nanowire, and the antenna substrate is by using polydimethylsiloxane (PDMS). The performance result of the proposed wearable antenna was simulated by using CST microwave studio. From the simulated result for different bending angles, a conclusion was drawn that bending of structure can improve the impedance matching and return loss during the bent condition. However, the resonant frequency tends to shift as the antenna is bent up to 50°. At the critical angle of 70°, the frequency is shifted to a lower frequency.
    Matched MeSH terms: Electric Impedance
  8. Nanostructure-assisted charge transfer in α-Fe2O3/g-C3N4 heterojunctions for efficient and highly stable photoelectrochemical water splitting
    Arzaee NA, Mohamad Noh MF, Mohd Ita NSH, Mohamed NA, Mohd Nasir SNF, Nawas Mumthas IN, et al.
    Dalton Trans, 2020 Aug 28;49(32):11317-11328.
    PMID: 32760991 DOI: 10.1039/d0dt00683a
    The development of semiconductor heterojunctions is a promising and yet challenging strategy to boost the performance in photoelectrochemical (PEC) water splitting. This paper describes the fabrication of a heterojunction photoanode by coupling α-Fe2O3 and g-C3N4via aerosol-assisted chemical vapour deposition (AACVD) followed by spin coating and air annealing. Enhanced PEC performance and stability are observed for the α-Fe2O3/g-C3N4 heterojunction photoanode in comparison to pristine α-Fe2O3 and the reason is systematically discussed in this paper. Most importantly, the fabricated α-Fe2O3/g-C3N4 film shows impressive stability, retaining more than 90% of the initial current over 12 h operating time. The excellent stability of the heterojunction photoanode is achieved due to the unique nanoflake structure of α-Fe2O3 induced by AACVD. This nanostructure promotes good adhesion with the g-C3N4 particles, as the particles tend to be trapped within the α-Fe2O3 valleys and eventually create strong and large interfacial contacts. This leads to improved separation of charge carriers at the α-Fe2O3/g-C3N4 interface and suppression of charge recombination in the photoanode, which are confirmed by the transient decay time, charge transfer efficiency and electrochemical impedance analysis. Our findings demonstrate the importance of nanostructure engineering for developing heterojunction structures with efficient charge transfer dynamics.
    Matched MeSH terms: Electric Impedance
  9. Fulltext Effects on the Properties after Addition of Lithium Salt in Poly(ethylene oxide)/Poly(methyl acrylate) Blends
    Abdul Halim SI, Chan CH, Kressler J
    Polymers (Basel), 2020 Dec 11;12(12).
    PMID: 33322501 DOI: 10.3390/polym12122963
    The studies of phase behavior, dielectric relaxation, and other properties of poly(ethylene oxide) (PEO)/poly(methyl acrylate) (PMA) blends with the addition of lithium perchlorate (LiClO4) were done for different blend compositions. Samples were prepared by a solution casting technique. The binary PEO/PMA blends exhibit a single and compositional-dependent glass transition temperature (Tg), which is also true for ternary mixtures of PEO/PMA/LiClO4 when PEO was in excess with low content of salt. These may indicate miscibility of the constituents for the molten systems and amorphous domains of the systems at room temperature from the macroscopic point of view. Subsequently, the morphology of PEO/PMA blends with or without salt are correlated to the phase behavior of the systems. Phase morphology and molecular interaction of polymer chains by salt ions of the systems may rule the dielectric or electric relaxation at room temperature, which was estimated using electrochemical impedance spectroscopy (EIS). The frequency-dependent impedance spectra are of interest for the elucidation of polarization and relaxation of the charged entities for the systems. Relaxation can be noted only when a sufficient amount of salt is added into the systems.
    Matched MeSH terms: Electric Impedance
  10. Fulltext Narrowband Array Processing Beamforming Technique for Electrical Impedance Tomography
    Chitturi V, Farrukh N
    J Electr Bioimpedance, 2019 Jan;10(1):96-102.
    PMID: 33584889 DOI: 10.2478/joeb-2019-0014
    Electrical impedance tomography (EIT) has a large potential as a two dimensional imaging technique and is gaining attention among researchers across various fields of engineering. Beamforming techniques stem from the array signal processing field and is used for spatial filtering of array data to evaluate the location of objects. In this work the circular electrodes are treated as an array of sensors and beamforming technique is used to localize the object(s) in an electrical field. The conductivity distributions within a test tank is obtained by an EIT system in terms of electrode voltages. These voltages are then interpolated using elliptic partial differential equations. Finally, a narrowband beamformer detects the peak in the output response signal to localize the test object(s). Test results show that the beamforming technique can be used as a secondary method that may provide complementary information about accurate position of the test object(s) using an eight electrode EIT system. This method could possibly open new avenues for spatial EIT data filtering techniques with an understanding that the inverse problem is more likely considered here as a source localization algorithm instead as an image reconstruction algorithm.
    Matched MeSH terms: Electric Impedance
  11. Fulltext Spotted hyena optimizer algorithm for capacitor allocation in radial distribution system with distributed generation and microgrid operation considering different load types
    Naderipour A, Abdul-Malek Z, Hajivand M, Seifabad ZM, Farsi MA, Nowdeh SA, et al.
    Sci Rep, 2021 Feb 01;11(1):2728.
    PMID: 33526829 DOI: 10.1038/s41598-021-82440-9
    In this paper, the optimal allocation of constant and switchable capacitors is presented simultaneously in two operation modes, grid-connected and islanded, for a microgrid. Different load levels are considered by employing non-dispatchable distributed generations. The objective function includes minimising the energy losses cost, the cost of peak power losses, and the cost of the capacitor. The optimization problem is solved using the spotted hyena optimizer (SHO) algorithm to determine the optimal size and location of capacitors, considering different loading levels and the two operation modes. In this study, a three-level load and various types of loads, including constant power, constant current, and constant impedance are considered. The proposed method is implemented on a 24-bus radial distribution network. To evaluate the performance of the SHO, the results are compared with GWO and the genetic algorithm (GA). The simulation results demonstrate the superior performance of the SHO in reducing the cost of losses and improving the voltage profile during injection and non-injection of reactive power by distributed generations in two operation modes. The total cost and net saving values for DGs only with the capability of active power injection is achieved 105,780 $ and 100,560.54 $, respectively and for DGs with the capability of active and reactive power injection is obtained 89,568 $ and 76,850.46 $, respectively using the SHO. The proposed method has achieved more annual net savings due to the lower cost of losses than other optimization methods.
    Matched MeSH terms: Electric Impedance
  12. Encapsulation of Ni0.8Zn0.2Fe2O4 single crystals in multiwall carbon nanotubes
    Yahya N, Akhtar MN, Koziol K
    J Nanosci Nanotechnol, 2012 Oct;12(10):8116-22.
    PMID: 23421187
    Magnetic nanoparticles in the hollow region of carbon nanotubes have attraction due to their changing physical electrical and magnetic properties. Nickel zinc ferrite plays an important role in many applications due to its superior magnetic properties. Ni0.8Zn0.2Fe2O4 single crystals were encapsulated in multiwall carbon nanotubes (MWCNTs). The magnetic nano crystals were prepared using a sol-gel self combustion method at the sintering temperature of 750 degrees C and were characterized by XRD, FESEM, TEM and VSM. Initial permeability, Q-factor and relative loss factor were measured by impedance vector network analyzer. XRD patterns were used for the phase identification. FESEM images show morphology and dimensions of the grains of Ni0.8Zn0.2Fe2O4 single crystals and Ni0.8Zn0.2Fe2O4 single crystals in MWCNTs. TEM images were used to investigate single crystal and encapsulation of Ni0.8Zn0.2Fe2O4 single crystals in the MWCNTs. VSM results confirmed super paramagnetic behaviour of encapsulated Ni0.8Zn0.2Fe2O4 single crystals. It was also attributed that encapsulated Ni0.8Zn0.2Fe2O4 single crystals in MWCNTs showed a higher initial permeability (51.608), Q-factor (67.069), and low loss factor (0.0002) as compared to Ni0.8Zn0.2Fe2O4 single crystals. The new encapsulated Ni0.8Zn0.2Fe2O4 single crystals in the MWCNTs may have potential applications in electronic and medical industries.
    Matched MeSH terms: Electric Impedance
  13. Fulltext A Multitasking Electrical Impedance Tomography System Using Titanium Alloy Electrode
    Salama A, Malekmohammadi A, Mohanna S, Rajkumar R
    Int J Biomed Imaging, 2017;2017:3589324.
    PMID: 29225613 DOI: 10.1155/2017/3589324
    This paper presents a multitasking electrical impedance tomography (EIT) system designed to improve the flexibility and durability of an existing EIT system. The ability of the present EIT system to detect, locate, and reshape objects was evaluated by four different experiments. The results of the study show that the system can detect and locate an object with a diameter as small as 1.5 mm in a testing tank with a diameter of 134 mm. Moreover, the results demonstrate the ability of the current system to reconstruct an image of several dielectric object shapes. Based on the results of the experiments, the programmable EIT system can adapt the EIT system for different applications without the need to implement a new EIT system, which may help to save time and cost. The setup for all the experiments consisted of a testing tank with an attached 16-electrode array made of titanium alloy grade 2. The titanium alloy electrode was used to enhance EIT system's durability and lifespan.
    Matched MeSH terms: Electric Impedance
  14. Fulltext Properties of CaCu3-XMn4+XO12 (X = 0.1, 0.3, 0.5, 0.7, 0.9) system synthesized via solid-state reaction
    Mohd Warikh Abd Rashid, Hutagalung, Sabar Derita, Zainal Arifin Ahmad
    Journal of Nuclear and Related Technologies, 2007;2007(1):63-70.
    MyJurnal
    A study on the effect of the modify values of x in CaCu3-xMn4+xO12 system has been carried out with x = 0.1, 0.3, 0.5, 0.7 and 0.9. The materials were prepared via solid-state reaction. The preparation conditions have been optimized using thermogravimetry analysis (TGA) technique. Material formations under the reported conditions have been confirmed by X-ray diffraction (XRD) studies. The results show that the formation of CaCu3Mn4O12 started at calcinations temperature of 600 0 C with the presence of raw material and was formed completely at 850 0 C. Field emission scanning electron microscopy (FESEM) analysis indicated that the increase of x value in the composition had changed the microstructures to be more faceted. The impedance spectrum is characterized by the appearance of two semicircle arcs whose pattern of evolution changes with rise of values x in the CaCu3-xMn4+xMn4O12 system. Bulk resistance (Rb) and grain boundary resistance (Rgb) of CaCu3- xMn4+xO12 decreases form 824.24 : to 98.68 : and 418.18 : to 2.20 : respectively, with the increasing of x value.
    Matched MeSH terms: Electric Impedance
  15. Fulltext Heat treatment effect with the electrode contact of CaCu3Ti4O12
    Muhammad Azwadi Sulaiman, Hutagalung, Sabar D., Zainal A. Ahmad
    Journal of Nuclear and Related Technologies, 2013;2013(2):43-52.
    MyJurnal
    CaCu3Ti4O12 (CCTO) has attracted a great attention for electronic devices miniaturization due to its
    very high dielectric constant properties at a wide range of frequency and nearly constant over broad temperature range. The origins of the giant dielectric constant have been speculated from electrical heterogeneous of interior elements of the CCTO ceramics. Four origins were suggested contributed to the electrical heterogeneous. In this study heat treatment were done with the electrode contact in Argon gas environment and the electrical properties over very wide frequency of CCTO ceramics were investigated. Cylindrical CCTO pellets samples were prepared by solid state reaction method and single phase of XRD pattern was obtained after sintering processes. Electrical impedance responds were measured at frequency from 100 Hz to 1 GHz for the samples for untreated and heat treated at 200ºC, 250ºC, 300ºC, 350ºC and 400ºC of CCTO. Improvement to the dielectric constant can be seen for 350ºC and 400ºC samples and dielectric loss were improved for 200ºC and 300ºC samples for overall frequency. The variations were discussed based on oxygen deficiency content and resistivity of the elements inside of CCTO structure.
    Matched MeSH terms: Electric Impedance
  16. Fulltext Optimization of Planar Monopole Wideband Antenna for Wireless Communication System
    Shakib MN, Moghavvemi M, Mahadi WN
    PLoS One, 2016;11(12):e0168013.
    PMID: 27992466 DOI: 10.1371/journal.pone.0168013
    In this paper, a new compact wideband monopole antenna is presented for wireless communication applications. This antenna comprises of a new radiating patch, a new arc-shaped strip, microstrip feed line, and a notched ground plane. The proposed radiating patch is combined with a rectangular and semi-circular patch and is integrated with a partial ground plane to provide a wide impedance bandwidth. The new arc-shaped strip between the radiating patch and microstrip feed line creates an extra surface on the patch, which helps further widen the bandwidth. Inserting one step notch on the ground plane further enhances the bandwidth. The antenna has a compact size of 16×20×1.6mm3. The measured result indicated that the antenna achieves a 127% bandwidth at VSWR≤2, ranging from 4.9GHz to 22.1GHz. Stable radiation patterns with acceptable gain are achieved. Also, a measured bandwidth of 107.7% at VSWR≤1.5 (5.1-17GHz) is obtained, which is suitable for UWB outdoor propagation. This antenna is compatible with a good number of wireless standards, including UWB band, Wimax 5.4 GHz band, MVDDS (12.2-12.7GHz), and close range radar and satellite communication in the X-band (8-12GHz), and Ku band (12-18GHz).
    Matched MeSH terms: Electric Impedance
  17. Fulltext Enhancement of Viscoelastic and Electrical Properties of Magnetorheological Elastomers with Nanosized Ni-Mg Cobalt-Ferrites as Fillers
    Abdul Aziz SA, Mazlan SA, Ubaidillah U, Shabdin MK, Yunus NA, Nordin NA, et al.
    Materials (Basel), 2019 Oct 28;12(21).
    PMID: 31661837 DOI: 10.3390/ma12213531
    Carbon-based particles, such as graphite and graphene, have been widely used as a filler in magnetorheological elastomer (MRE) fabrication in order to obtain electrical properties of the material. However, these kinds of fillers normally require a very high concentration of particles to enhance the conductivity property. Therefore, in this study, the nanosized Ni-Mg cobalt ferrite is introduced as a filler to soften MRE and, at the same time, improve magnetic, rheological, and conductivity properties. Three types of MRE samples without and with different compositions of Mg, namely Co0.5Ni0.2Mg0.3Fe2O4 (A1) and Co0.5Ni0.1Mg0.4Fe2O4 (A2), are fabricated. The characterization related to the micrograph, magnetic, and rheological properties of the MRE samples are analyzed using scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and the rheometer. Meanwhile, the effect of the nanosized Ni-Mg cobalt ferrites on the electrical resistance property is investigated and compared with the different Mg compositions. It is shown that the storage modulus of the MRE sample with the nanosized Ni-Mg cobalt ferrites is 43% higher than that of the MRE sample without the nanomaterials. In addition, it is demonstrated that MREs with the nanosized Ni-Mg cobalt ferrites exhibit relatively low electrical resistance at the on-state as compared to the off-state condition, because MRE with a higher Mg composition shows lower electrical resistance when higher current flow occurs through the materials. This salient property of the proposed MRE can be effectively and potentially used as an actuator to control the viscoelastic property of the magnetic field or sensors to measure the strain of the flexible structures by the electrical resistance signal.
    Matched MeSH terms: Electric Impedance
  18. Fulltext Employing of Trukhan Model to Estimate Ion Transport Parameters in PVA Based Solid Polymer Electrolyte
    Aziz SB, B Marif R, Brza MA, Hamsan MH, Kadir MFZ
    Polymers (Basel), 2019 Oct 16;11(10).
    PMID: 31623158 DOI: 10.3390/polym11101694
    In the current paper, ion transport parameters in poly (vinyl alcohol) (PVA) based solid polymer electrolyte were examined using Trukhan model successfully. The desired amount of lithium trifluoromethanesulfonate (LiCF3SO3) was dissolved in PVA host polymer to synthesis of solid polymer electrolytes (SPEs). Ion transport parameters such as mobility (μ), diffusion coefficient (D), and charge carrier number density (n) are investigated in detail using impedance spectroscopy. The data results from impedance plots illustrated a decrement of bulk resistance with an increase in temperature. Using electrical equivalent circuits (EEC), electrical impedance plots (ZivsZr) are fitted at various temperatures. The results of impedance study demonstrated that the resistivity of the sample decreases with increasing temperature. The decrease of resistance or impedance with increasing temperature distinguished from Bode plots. The dielectric constant and dielectric loss values increased with an increase in temperature. The loss tangent peaks shifted to higher frequency region and the intensity increased with an increase in temperature. In this contribution, ion transport as a complicated subject in polymer physics is studied. The conductivity versus reciprocal of temperature was found to obey Arrhenius behavior type. The ion transport mechanism is discussed from the tanδ spectra. The ion transport parameters at ambient temperature are found to be 9 × 10-8 cm2/s, 0.8 × 1017 cm-3, and 3 × 10-6 cm2/Vs for D, n, andμ respectively. All these parameters have shown increasing as temperature increased. The electric modulus parameters are studied in an attempt to understand the relaxation dynamics and to clarify the relaxation process and ion dynamics relationship.
    Matched MeSH terms: Electric Impedance
  19. Fulltext Analysis on the Effects of the Human Body on the Performance of Electro-Textile Antennas for Wearable Monitoring and Tracking Application
    Abd Rahman NH, Yamada Y, Amin Nordin MS
    Materials (Basel), 2019 May 19;12(10).
    PMID: 31109128 DOI: 10.3390/ma12101636
    Previous works have shown that wearable antennas can operate ideally in free space; however, degradation in performance, specifically in terms of frequency shifts and efficiency was observed when an antenna structure was in close proximity to the human body. These issues have been highlighted many times yet, systematic and numerical analysis on how the dielectric characteristics may affect the technical behavior of the antenna has not been discussed in detail. In this paper, a wearable antenna, developed from a new electro-textile material has been designed, and the step-by-step manufacturing process is presented. Through analysis of the frequency detuning effect, the on-body behavior of the antenna is evaluated by focusing on quantifying the changes of its input impedance and near-field distribution caused by the presence of lossy dielectric material. When the antenna is attached to the top of the body fat phantom, there is an increase of 17% in impedance, followed by 19% for the muscle phantom and 20% for the blood phantom. These phenomena correlate with the electric field intensities (V/m) observed closely at the antenna through various layers of mediums (z-axis) and along antenna edges (y-axis), which have shown significant increments of 29.7% in fat, 35.3% in muscle and 36.1% in blood as compared to free space. This scenario has consequently shown that a significant amount of energy is absorbed in the phantoms instead of radiated to the air which has caused a substantial drop in efficiency and gain. Performance verification is also demonstrated by using a fabricated human muscle phantom, with a dielectric constant of 48, loss tangent of 0.29 and conductivity of 1.22 S/m.
    Matched MeSH terms: Electric Impedance
  20. Electrochemical impedance spectroscopy and surface studies of steel corrosion by sulphate-reducing bacteria
    Fathul Karim Sahrani, Zaharah Ibrahim, Adibah Yahya, Madzlan Aziz
    Sains Malaysiana, 2009;38.
    Sulphate-reducing bacteria (SRB), implicated in microbiologically influenced corrosion were isolated from the deep subsurface at the vicinity of Pasir Gudang, Johor, Malaysia. Electrochemical impedance spectroscopic (EIS) study was carried out to determine the polarization resistance in various types of culturing solutions, with SRB1, SRB2, combination of SRB1 and SRB2 and without SRBs inoculated (control). EIS results showed that in the presence of SRB1, SRB2 and mixed culture SRB1 and SRB2, polarisation resistance values were 7170, 6370 and 7190 ohms respectively compared to that of control, 92400 ohm. X-ray analysis (EDS) of the specimens indicated high sulphur content in the medium containing SRBs. Localized corrosion was observed on the metal surface which was associated with the SRB activity.
    Matched MeSH terms: Electric Impedance
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