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Dielectrics and Electrical Insulation, IEEE Transactions on

Issue 5 • Date October 2009

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  • IEEE Transactions on Dielectrics and Electrical Insulation [Front cover]

    Publication Year: 2009 , Page(s): c1
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    Freely Available from IEEE
  • IEEE Dielectrics and Electrical Insulation Society - Executive Committee

    Publication Year: 2009 , Page(s): c2
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    Freely Available from IEEE
  • Bioelectrics - [editorial)

    Publication Year: 2009 , Page(s): 1223
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    The purpose of the special issue on bioelectrics is to present research findings pertaining to the electric properties of biological cell membranes and the bioengineering applications of electrical membrane effects, and to inform the wider electrical engineering community about this exciting new research field. View full abstract»

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  • A scaling law for membrane permeabilization with nanopulses

    Publication Year: 2009 , Page(s): 1224 - 1235
    Cited by:  Papers (11)
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    Experimental studies of plasma membrane permeabilization, caused by single, intense, submicrosecond square wave pulses, indicate that the product of electric field amplitude and pulse duration (the electrical impulse) can be considered a similarity or scaling factor. A model based on the hypothesis that the intensity of membrane permeabilization effects is linearly dependent on the electric charge transferred through the permeabilized membrane, provides results, which are consistent with the empirical observations. For multiple pulses, bioelectric effects caused by ultrashort pulses were found to scale with the square root of the pulse number. This square root dependence on the pulse number points to a statistical motion of cells between pulses with respect to the applied electric field, and can be explained using an extension of the random walk statistical results to random rotations. Besides membrane permeabilization, the scaling law has also been shown to hold for secondary bioelectric effects, which are caused by permeability changes in the plasma membrane or subcellular membranes. View full abstract»

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  • Measurement protocol for planar lipid bilayer viscoelastic properties

    Publication Year: 2009 , Page(s): 1236 - 1242
    Cited by:  Papers (1)
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    This paper describes how to estimate planar lipid bilayer's elasticity module E and surface tension sigma by means of measuring its breakdown voltage and using Dimitrov's viscoelastic model of electric field-induced breakdown of lipid bilayers. Planar lipid bilayers (BLMs) were made of two components: 1-palmitoyl 2-oleoyl phosphatidylcholine (POPC) and 1-palmitoyl 2-oleoyl phosphatidylserine (POPS) in five different compositions. Folding method for forming planar lipid bilayers in the salt solution of 100 mM KCl was used. Breakdown voltages Ubr and membrane life times tbr were measured by means of applying linear rising voltage signals of seven different slopes. Specific capacitances cBLM of bilayers were measured with charge pulse method. Then Dimitrov's viscoelastic model was fitted to measured data allowing for estimation of elasticity module and surface tension of the lipid bilayer. Our results show that onecomponent bilayers composed from POPS were more stable and thus having higher breakdown voltages and elasticity moduli then bilayers composed of POPC. Surface tension values were similar regardless of the membrane composition. Values of the elasticity (E) and surface tension (sigma) are comparable to those published in the literature. We conclude that the protocol used, though time consuming, is an alternative to other methods used for determination of bilayer's mechanical properties. View full abstract»

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  • Aspects of lipid membrane bio-responses to subnanosecond, ultrahigh voltage pulsing

    Publication Year: 2009 , Page(s): 1243 - 1250
    Cited by:  Papers (3)
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    Membrane electroporation is probably one of the best-known effects of applying external voltages to biological cells. Reports in the literature have focused on relatively long voltage pulse durations (100 ns-1 ms). Here we probe the very short (< 1 ns), but intense electric field (> 500 kV/cm) regime that is made possible by advances in pulsed power technology. Our analyses based on continuum Smoluchowski and molecular dynamics (MD) approaches, predict two new aspects. First, it is shown that pore formation rates would be dramatically lower than predicted by conventional theory due to their dependence on local pore area. Second, such high fields are predicted to affect membrane proteins and ion-channels, without causing electroporation in regions between the proteins. Hence, such high voltage, short duration pulsing should not be associated with electroporation alone, but rather be viewed as a novel vehicle that opens possibilities for a range of new electrically-driven bio-response phenomena. View full abstract»

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  • The role of plasmalemmal-cortical anchoring on the stability of transmembrane electropores

    Publication Year: 2009 , Page(s): 1251 - 1258
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    The structure of eukaryotic cells is maintained by a network of filamentous actin anchored subjacently to the plasma membrane. This structure is referred to as the actin cortex. We present a locally constrained surface tension model for electroporation in order to address the influence of plasmalemmal-cortical anchoring on electropore dynamics. This model predicts that stable electropores are possible under certain conditions. The existence of stable electropores has been suggested in several experimental studies. The electropore radius at which stability is achieved is a function of the characteristic radii of locally constrained regions about the plasma membrane. This model opens the possibility of using actin-modifying compounds to physically manipulate cortical density, thereby manipulating electroporation dynamics. It also underscores the need to improve electroporation models further by incorporating the influence of trans-electropore ionic and aqueous flow, cortical flexibility, transmembrane protein mobility, and active cellular wound healing mechanisms. View full abstract»

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  • Window effect of pulsed electric field on biological cells

    Publication Year: 2009 , Page(s): 1259 - 1266
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    Based on multilayer dielectric model, for the spherical biological cell subjected to pulsed electric field (PEF), an equivalent circuit model is presented. Frequency-domain analysis shows that inner and outer membranes exhibit band-pass and low-pass filter characteristics in response to PEF, respectively. Therefore, different biomedical effects will be induced by the field with different frequency spectrum. The method to calculate the transmembrane potentials induced by time-varying PEF is introduced, and the relationship between rectangular pulse and transmembrane potentials is also discussed. It is found that because of different charging time constants, different durations have selective effects on inner and outer membranes. The analyses in both the frequency-domain and time-domain show a window effect of PEF on biological cells. When duration is reduced from microsecond to submicrosecond, and to nanosecond, the target induced is changed from the outer membrane to the inner membrane gradually. The window effect gives preliminary explanation for various bioelectric effects such as electroporation, intracellular electro manipulation and nanopores, providing help to the applications of PEF in tumor treatment. View full abstract»

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  • Double pulse approach of electropulsation: a fluorescence analysis of the nucleus perturbation at the single cell level

    Publication Year: 2009 , Page(s): 1267 - 1272
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    Plasmid Gene transfer and expression can be obtained by the application of electric pulses to a mixture of cells and plasmids (electrogenetherapy, EGT). Electropulsation is rather well characterized at the plasma membrane level. But, the transfer to and across the nuclear envelope remains a problem. Biological approaches showed that EGT was more effective during mitosis. Recently the group of Schoenbach showed that nanosecond ultra high field pulses may affect cytoplasmic organelles including the nucleus. The need for high field was linked on one hand on the time scale and on the other on the size of the target. Therefore we made an approach of the alteration of the nucleus induced by a microsecond high electric pulse (mus HV, up to 9 kV/cm, 5 mus). This perturbation was operated alone or a few seconds after EGT pulses (10x, 0.7 kV/cm, 5 ms) needed to introduce the plasmid in the cytoplasm. Structural alterations of the nucleus organization were investigated. This was obtained by a digitized fluorescence approach at the single cell level, using Hoechst dye as a probe with a high affinity to nucleic acids. The first train of pulses (EGT) induced a huge and rapid (<2min) swelling of cells and of their nucleus associated with a decrease of the mean fluorescence of the nucleus. Mean fluorescence level and volume changes were maintained along the next 10 minutes. The application of a mus HV pulse affects the cell volume and transiently the nucleus volume without any effects on the mean fluorescence level in the nucleus. View full abstract»

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  • Changes in electrical impedance of biological matter due to the application of ultrashort high voltage pulses

    Publication Year: 2009 , Page(s): 1273 - 1279
    Cited by:  Papers (3)
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    Time domain-based impedance measurements were used to study the changes in electrical parameters of biological samples following the application of ultrashort high voltage (HV) pulses. Pulses with very short duration (300 ns) caused a significant drop in post pulse resistance of the plasma membrane only at high field strengths in excess of 20 kV/cm. The conductivity of the plasma membrane returned to almost pre-pulse values within less than 10 ms after the field was applied. Further steps of recovery, attributed to pore shrinking and resealing with an exponential decay of the conductivity, as is expected in electroporation, were not observed. An increase in medium conductance, as recorded minutes after the pulse, arises mainly from cell damage. Although pore formation is a possible effect of the high electric field, our results suggest further disturbance of the membrane-like micelle formation or even the creation of large defects, forced by mechanical tension within the cell membrane. View full abstract»

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  • Electrostrictive forces on vesicles with compartmentalized permittivity and conductivity conditions

    Publication Year: 2009 , Page(s): 1280 - 1287
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    Electrostrictive forces on the plasma membrane of a lipid bilayer vesicle that result as a consequence of an applied electric field and differential dielectric material properties can be calculated via the Maxwell stress tensor. In this situation, the plasma membrane is proposed as a barrier that separates compartments of a system with different conductivity and relative permittivity values. A numerical model of this case is presented. Model force calculations compare with analytical equation results and were used to validate published experimental work. The model also was used to study electrostatic forces in a simple vesicle system contrasting such forces to frequency dependent deformations. Model results for vesicles in variable conductivity and relative permittivity environments are analyzed to build a framework with the potential to become a tool to study more complex problems with multiple compartments such as cells and tissues. Impedance spectroscopy is also explored as a potential experimental method to predict cell and tissue system behavior in the presence of electric fields. View full abstract»

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  • Intracellular DNA damage induced by non-thermal, intense narrowband electric fields

    Publication Year: 2009 , Page(s): 1288 - 1293
    Cited by:  Papers (3)
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    Intracellular DNA damages caused by intense burst sinusoidal electric fields (IBSEFs) were investigated by means of an alkaline comet assay method. Non-thermal, 200 mus-long IBSEF with various frequency values (300 kHz-100 MHz) and strengths (up to 200 kV/m) was applied to Chinese hamster ovary (CHO) cells in a suspending medium between 1 mm gap parallel electrodes. The comet assay suggests that 100 kV/m IBSEF with frequencies exceeding 1 MHz or 100 MHz IBSEFs with field strengths exceeding 3 kV/m induces significant DNA damage. According to the numerical calculation of the electric field over a simplified cell model under an alternating electric field, the intracellular field strength increases with increasing alternating frequency. The minimum level of the field strength that induces the DNA damage is in the range of 10-30 kV/m. This intracellular strong field might trigger biological processes leading to the DNA damage. View full abstract»

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  • Nanosecond electric pulse-induced increase in intracellular calcium in adrenal chromaffin cells triggers calcium-dependent catecholamine release

    Publication Year: 2009 , Page(s): 1294 - 1301
    Cited by:  Papers (3)
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    Experimental results on the effect of a single 5-6 ns, 5-7 MV/m electric pulse on electrically excitable bovine chromaffin cells are presented. Effects on intracellular calcium level were assessed by loading the cells with the calcium-sensitive fluorescence indicator calcium green and imaging the cells during nanosecond field exposure in microelectrode chambers that were fabricated on a glass microscope slide with gold electrodes. Consistent with earlier findings that utilized different microelectrode chambers for pulse exposure, a single pulse elicited a rapid and transient rise in intracellular calcium by a mechanism that depends on extracellular calcium, which appears to enter the cells largely through voltage-gated calcium channels. In parallel experiments to assess catecholamine release, chromaffin cells were placed into electroporation cuvettes for nanosecond pulse exposure. As measured by high performance liquid chromatography coupled with electrochemical detection, a single pulse elicited an increase in both norepinephrine and epinephrine release that was also dependent on extracellular calcium and involved influx of calcium through voltage gated-calcium channels. Taken together these results indicate that a single nanosecond pulse can act as a stimulus to trigger calcium-dependent catecholamine release from chromaffin cells. View full abstract»

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  • Apoptosis induction effects of steep pulsed electric fields (SPEF) on human liver cancer cell SMMC-7721 in vitro

    Publication Year: 2009 , Page(s): 1302 - 1310
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    To research the apoptosis effects of steep pulsed electric fields (SPEF) on human liver cancer cell SMMC-7721 in vitro, this paper studied phosphatidylserine (PS) externalization detection utilizing flow cytometry, real-time change of mitochondrial transmembrane potential (DeltaPsim) using confocal laser scanning microscope (CLSM) and DNA fragmentation assay by agarose gel electrophoresis. The experiment results by flow cytometry showed that musSPEF (SPEF with electric field intensity of 200 V/cm and duration of 1.3 mus) effectively (P<0.05) induced PS externalization but nsSPEF (SPEF with electric field intensity of 600 V/cm and duration of 100 ns) did not (P>0.05). On the contrary, nsSPEF induced DeltaPsim decrease and DNA fragmentation more notably than musSPEF. These results indicate that SPEF can distinctly induce apoptosis and the effects are electric field intensity/pulse duration-dependent. Theoretically calculation showed that temperature increase of cell solutions for treated groups exposed to SPEF was less than 1.3 K without regard to heat dissipation. Multi-shelled dielectric cell model and frequency spectrum analysis showed that musSPEF contained abundant low frequency components which mainly acted on plasma membrane, whereas nsSPEF contained plentiful high frequency components which permeated plasma membrane and mainly affected on intracellular organelle. View full abstract»

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  • Effects of nanosecond pulsed electric fields on the human prostate cancer cell line LNCaP

    Publication Year: 2009 , Page(s): 1311 - 1316
    Cited by:  Papers (1)
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    The effects of nanosecond pulsed electric fields (nsPEF) on the human prostate cancer cell line LNCaP was investigated for changes in protein and DNA concentrations as well as for the 11beta hydroxysteroid dehydrogenase type 2 (11betaHSD2) enzyme activity. Electric fields with intensities of 32.5 kV/cm and pulse widths of 60 ns were applied to cancer cells in trains of 1, 5, and 10 pulses. Protein concentrations were determined through a Bio-Rad DC protein assay, while Hoechst 33258 was used to quantify DNA concentrations. The analyses showed that protein concentrations decreased by 18.77% and 19.04% for 1 and 10 pulses, respectively, while DNA concentrations decreased by 5.29%, 8.95%, and 18.36% for 1, 5, and 10 pulses, respectively, as compared to control groups. The 11betaHSD2 enzyme activity in LNCaP cells also decreased following exposure, thus supporting our initial hypothesis that ultrashort pulses affect intracellular structures; thus, a decrease in the enzyme activity could result in enhancing the anti-proliferative actions of glucocorticoids. View full abstract»

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  • Germination rate studies of soybean under static and low-frequency magnetic fields

    Publication Year: 2009 , Page(s): 1317 - 1321
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    A Helmholtz coil was designed and characterized to study the effects of magnetic fields on the germination rate of soybeans. The coil provides a uniform field in a large area such that all the seeds are equally exposed to radiation. An in-house computer code was developed to study the field intensity, specifically the cross-sectional area of uniform field. Experimental results indicate that soybeans grown under static low intensity and super low frequency magnetic fields show improved growth and germination rates when compared to those in the control group. Soybean has potential applications as a renewable energy source for biofuels. View full abstract»

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  • Effects of nanosecond pulsed electric field exposure on arabidopsis thaliana

    Publication Year: 2009 , Page(s): 1322 - 1328
    Cited by:  Papers (8)
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    Seven days old seedlings of Arabidopsis thaliana, suspended in a 0.4 S/m buffer solution were exposed to nanosecond pulsed electric fields (nsPEF) with a duration of 10 ns, 25 ns and 100 ns. The electric field was varied from 5 kV/cm up to 50 kV/cm. The specific treatment energy ranged between 100 J/kg and 10 kJ/kg. Due to electroporation of the plasma membrane of the plant cells, the seedlings completely died off, when 100 ns pulses and high electric field pulses were applied. But even at the highest specific treatment energies, 10 ns pulses had no lethal effect on the seedlings. An evaluation of the leaf area 5 and 7 days after pulsed electric field treatment revealed values twice the area of sham treated seedlings up to a specific treatment energy of 4 kJ/kg, when the applied field amplitude was low or the pulse duration 10 ns. A growth stimulating effect after short pulse exposition clearly could be detected. Contrary to the growth inhibiting effect of plasma membrane electroporation on the seedlings, a growth stimulation by nsPEF treatment does not scale with the treatment energy within the applied parameter range. View full abstract»

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  • Electric measurement of the electroporation efficiency of mash from wine grapes

    Publication Year: 2009 , Page(s): 1329 - 1337
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2336 KB) |  | HTML iconHTML  

    The degree of cell opening after electroporation can be derived from an electric impedance measurement in a frequency range between 500 Hz and 10 MHz. For a simple detection in a continuously flowing medium a measurement at a discrete frequency evaluating the phase shift between a measurement voltage across an electrode system and a current flowing through the sample volume has been investigated. The paper describes impedance measurements of the mash of wine grapes. For different grape varieties the frequency dependency of the phase shift has been measured. The data showed that the frequency of maximum phase shift differs with the grape variety. For the mash of wine grapes the measurement results based on the measurement of the complex impedance have been compared to the degree of extraction of color from the peel tissue of red wine grapes as a conventional method to determine the degree of denaturation. The measurements showed a correspondence between the color intensity of the must and the electric measurements. View full abstract»

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  • Three-dimensional finite-element analysis of joule heating in electrochemotherapy and in vivo gene electrotransfer

    Publication Year: 2009 , Page(s): 1338 - 1347
    Cited by:  Papers (5)
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    Electrochemotherapy and electrogene therapy are new methods in molecular medicine based on electroporation-mediated introduction of foreign molecules (chemotherapeutic drugs, DNA) into target cells in vivo. Electrochemotherapy involves the injection of chemotherapeutic agent followed by a local delivery of a train of short high-voltage pulses to the tumor nodule (i.e. 8 square-wave pulses of 100 mus duration delivered at the repetition frequency of 1 Hz or several kHz, with a voltage-to-distance ratio of up to 1500 V/cm). For the transfer of DNA across a cell membrane a train of long low-voltage pulses (i.e. 8 rectangular pulses of 50 ms duration delivered at the repetition rate of 1 Hz, with a voltage-to-distance ratio up to 250 V/cm) is much more effective due to the electrophoretic effect on DNA molecule. In this paper we present a comprehensive analysis of tissue heating as a potential side effect of electric pulses used for electroporation-based treatments. The analysis is based on a coupled electrothermal model using 3-D finite-element approach. We studied two electrode geometries: parallel plates and a pair of needles. By setting the appropriate boundary conditions, we simulated driving of electrodes with short, high-voltage, electropermeabilizing pulses and with longer, lower voltage, electrophoretic pulses. We obtained time dependent solutions for electric field and temperature distribution by FEM solver. Based on the numerical simulations we analyzed the influence of tissue electrical conductivity and parameters of electric pulses (amplitude, duration, number of pulses, pulse repetition frequency) on the temperature distribution within the tissue and the electrodes. Results of our simulations show that at specific pulse parameters at least locally tissue heating might be significant (i.e. tissue temperatures to grow in excess of 43degC). For electrochemotherapy, this is not critical, but DNA electrotransfer may be unsuccessful due to heating-related DNA da- mage or denaturation. View full abstract»

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  • Effectiveness of non-penetrating electroporation applicators to function as impedance spectroscopy electrodes

    Publication Year: 2009 , Page(s): 1348 - 1355
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    Electroporation is commonly performed to deliver drugs and genes to cells comprising tissues. A possible way to control and confirm delivery is through the use of impedance spectroscopy. Ideally, this tool should not interfere with delivery and should incorporate the use of electrodes, applicators, used for delivery. This work examines impedance spectra obtained with non-penetrating surface applicators commonly used for skin electroporation. After collecting and processing over 9,000 spectra from three animal models it was determined that the electrode systems tested would have no significant effect on the obtained spectra. Therefore, electroporation applicators currently in use could be used concurrently for the collection of impedance spectra. View full abstract»

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  • Computer aided modelling of an interdigitated microelectrode array impedance biosensor for the detection of bacteria

    Publication Year: 2009 , Page(s): 1356 - 1363
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB) |  | HTML iconHTML  

    Electrostatic finite element modelling software and an ac equivalent circuit model have been used to investigate an impediometric microelectrode array biosensor for the detection of bacteria. The electrostatic model showed the capacitance of the biosensor to decrease with increasing numbers of bacteria trapped on the sensor's surface in a suspension of relatively high dielectric permittivity. Optimization of the model suggests that reducing the spatial wavelength of the biosensor's electrodes either through a decrease in electrode width or gap will improve the sensor's sensitivity. In addition, the model confirmed that the permittivity of the external medium had a significant effect on detection efficiency. Increased sensitivity in suspensions of lower relative dielectric permittivity was observed. The equivalent circuit model (ECM) was used to analyze the effect of high levels of immobilized bacteria at fixed signal frequencies (100 Hz and 1 MHz). It has been shown that the ECM discussed in this paper is able to successfully model the experimental data for the actual sensor in the low frequency ranges, allowing prediction of the sensor response and analysis of its performance. Overall, the modelling results obtained in the present paper are in general agreement with those from other published data and can be used in the development and optimization of impediometric biosensors for rapid and reliable detection of pathogenic bacteria. View full abstract»

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  • Design of a special dielectric lens for concentrating a subnanosecond electromagnetic pulse on a biological target

    Publication Year: 2009 , Page(s): 1364 - 1375
    Cited by:  Papers (8)
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    Analytical design procedures, numerical simulations and preliminary experimental results of a dielectric lens concentrating the field on a target are discussed. A quarter spherical electromagnetic lens with subsequent layers is used to obtain better focusing, smaller spot size and elimination of the reflection at the second focal point of a prolatespheroidal impulse radiating antenna for skin cancer treatment. View full abstract»

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  • Luminescence and space charge in polymeric dielectrics - [whitehead memorial lecture (2008)]

    Publication Year: 2009 , Page(s): 1376 - 1392
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8646 KB) |  | HTML iconHTML  

    Polymers are extensively used as insulating material in high voltage devices, such as underground power cables, power capacitors and transformers. During normal operation the polymeric insulation of a power device is not only subjected to electrical stresses, but could also be subjected to other stresses that can cause the degradation and ultimately lead to insulation failure. It has been well established that electroluminescence and charge injection, which gives rise to space charge in the polymeric insulation, occur at ac, dc and impulse field above a certain threshold value. Space charge can cause dissipative energetic processes such as photon and phonon emission, increase the local electric field and reduce the withstand voltage of the insulation. This paper describes the characteristics of electroluminescence in polymeric insulation subjected to ac voltage and shows its relevance to space charge injection in the material. It is shown that insulation subjected to high voltage could emit various types of light but electroluminescence emission which is related to space charge injection can be clearly distinguished from these other types of light emission. The electroluminescence technique is a valuable tool to evaluate the dielectric properties of novel insulating materials, such as nanodielectrics. View full abstract»

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  • Analytical evaluation of dielectric breakdown test based on one-minute step-up method

    Publication Year: 2009 , Page(s): 1393 - 1396
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    The authors previously pointed out that the results of insulation tests based on the one-minute step-up method deviate from the "true values". In the present study, these deviations are evaluated by numerical simulations. These deviations were found to exist not only under limited conditions in numerical simulations but to exist fundamentally on the one-minute step-up test method. This should be taken into consideration when making actual insulation designs. View full abstract»

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  • Effect of humidity on the breakdown characteristics of air in uniform field for the very low frequency (VLF) band

    Publication Year: 2009 , Page(s): 1397 - 1403
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (841 KB) |  | HTML iconHTML  

    The paper reports about the role of humidity and frequency on the electrical breakdown of air in uniform field gaps. Experiments were conducted on Rogowski-profile electrodes with gap lengths ranging from 5 to 53 mm at power frequency (60 Hz) and frequencies in the range of 18-50 kHz, corresponding to the VLF/LF bands used for long-range communication. The results show that breakdown voltage at VLF decreases with humidity, opposite to that observed at 60 Hz. Breakdown mechanisms for explaining this important phenomenon are proposed. A correction factor to calculate breakdown voltage as a function of humidity for VLF is presented. View full abstract»

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Aims & Scope

IEEE Transactions on Dielectrics and Electrical Insulation contains topics concerned with dielectric phenomena and measurements with development and characterization of gaseous, vacuum, liquid and solid electrical insulating materials and systems.

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Reuben Hackam