Application Of Electric Pulse Research Articles

Application of electric pulse and ultrasonic mufflers for increasing the degree of exhaust gas purification in car engines

The purpose of the article is to compare the efficiency of using electro-pulse and ultrasonic mufflers for cleaning exhaust gases from internal combustion engines of automobiles. The authors have developed full-size stands for conducting experiments with both types of mufflers on gasoline and diesel engines. Experimental studies have shown that electro-pulse mufflers are more effective in reducing the smoke of diesel engine exhausts, while ultrasonic mufflers are promising for cleaning exhaust gases from solid particles of gasoline engines. In the electro-pulse muffler, at the considered values of the angular velocity of the engine, the smoke indicators of the gas decreased to approximately 30%, while in the ultrasonic one, to 15%. The changes in the mass of the sold particles in the ultrasonic muffler of a diesel engine and a comparison with a gasoline engine show that ultrasonic mufflers have a lot of potential to stop solid particles from forming in the gas flow. In particular, the mass of the precipitated particles in a gasoline engine is 3 times greater than in a diesel engine. The alternative mufflers studied in the article allow for the purification of exhaust gases from solid particles, reducing their negative impact on the environment and giving impetus to the development of environmentally friendly motor transport.

Effect of electropulsing treatment on the precipitation behavior of MnS in sulfur-containing microalloyed 49MnVS3 steel

An experimental investigation has been conducted with respect to the influence of electropulsing treatment (EPT) on the 2D and 3D morphologies, distribution, number and size of MnS precipitates in the high-sulfur micro-alloyed 49MnVS3 steel. After the application of electric current pulse with a peak pulsed voltage of 30 V, the microstructure was refined due to the increasing nucleation rate of particles in liquid steel. Moreover, compared with the untreated steel with spherical MnS randomly distributed in the matrix, the MnS precipitates moved directionally to aggregate on the bottom and top surfaces of the ingot in order to minimize the free energy of the system in case of EPT. For untreated steel samples, the number of MnS was 409 (bottom), 579 (middle) and 437 (top), while that of the treated samples were 226 (bottom), 38 (middle) and 224 (top) in the scanning area of 2.65 × 107 µm2 with ASPEX. The number of MnS with small size decreased while the large-size MnS increased with the application of EPT.

Designing Ultrafast Cooling Rate for Room Temperature Electrocaloric Effects by Phase‐Field Simulations

AbstractDue to miniaturization and environmental friendliness, the electrocaloric effect is expected to be applied to refrigerate electronic chips and microdevices. Unlike the conventional electrocaloric effect that focuses on the temperature change, the ultrafast cooling rate is crucial to heat transport in future device units. In this work, controlling the duration of ultrafast electric field pulse on a nanosecond scale (the frequency ∼ GHz), the instant electrocaloric effect is realized in BaTiO3 and Ba(1−x)SrxTiO3 systems based on the modified phase‐field method. A significant ultrafast cooling rate of 108 K s−1 can be achieved due to the application of ultrafast electric field pulse within nanoseconds, which proved to be more efficient than the constant electric field. Furthermore, multiple electric field pulses are designed to realize the cyclic ultrafast cooling. This study provides the fundamental theoretical guidance for ultrafast cooling in solid‐state refrigeration.

Embrittlement of 316L stainless steel in electropulsing treatment

Electropulsing treatment is known to induce the so-called electroplastic effect, which is accompanied by an increase in ductility of metals. However, in this study we find that the application of electric current pulse reduces the flow stress and strain-to-failure in a 316L stainless steel, and it also induces premature fracture with a fracture mode transition from full ductile to partial transgranular cleavage. The results indicate a reverse electroplastic effect, i.e. electropulsing-induced embrittlement. By using transmission electron microscopy (TEM), it is found that the dislocation cell structure became refined, and the density of deformation-induced twins increased as increasing the voltage. The variation of dislocation structure cannot be solely attributed to the heating of sample due to electricity. The embrittlement is believed to be a synthetic effect of Joule heat and electropulsing-enhanced dislocation motion.

Rapid and Effective Electroporation Protocol for Nannochloropsis oceanica.

Electroporation refers to the application of high strength electric pulse to create transient pores in the membrane, thereby enabling the passage of hydrophilic molecules into the cells. Based on the properties of cell and cell wall, the electroporation parameters vary among the algal species. Here, we demonstrated the optimized protocol for successful introduction of recombinant DNA (~5000bp) into Nannochloropsis oceanica. The linearized recombinant plasmid that harbors eGFP and Bh-sle as the reporter and marker gene, respectively, was electroporated into the electrocompetent N. oceanica cells at voltage of 2200V, 50μF, resistance at 600Ω using electroporator, and the transformed cells were then screened by molecular analysis. The report exemplifies a straightforward and reliable electroporation strategy for generating transgenic N. oceanica cells.

Grain refinement and strength enhancing of hot extruded Mg alloy by application of electric pulse

A novel method was proposed to refine the grain structure and enhance the strength of extruded AZ91 alloys by electric pulse. The grain structure was refined to the average size of 2.25 μm due to the strong athermal effects. The size of Mg17Al12 phase was greatly reduced and its distribution became much more dispersive. The strong {0 0 0 1} basal texture with c-axis parallel with normal direction appeared, and its intensity was slightly increased. The specimen extruded by electric pulse with the peak current density of 117.4 A/mm2 exhibited the highest yield strength of 221 MPa and tensile strength of 384 MPa.

DC Stark addressing for quantum memory in Tm:YAG

We observed a linear DC Stark effect for 3 H 6 – 3 H 4 optical transition of Tm 3+ ions in Y 3 Al 5 O 12 . We observed that application of electric field pulse suppresses the two-pulse photon echo signal. If we then apply a second electric pulse of opposite polarity the echo signal is restored again, which indicates the linear nature of the observed effect. The effect is present despite the D 2 symmetry of the Tm 3+ sites that prohibits a linear Stark effect. Experimental data analysis shows that the observed electric field influence can be attributed to defects that break the local crystal field symmetry near Tm 3+ ions. Using this effect we demonstrate selective retrieval of light pulses in two-pulse photon echo.

Effect of electrodes and thermal insulators on grain refinement by electric current pulse

The application of electric current pulse (ECP) to a solidification process refers to the immersion of electrodes into the liquid metal and the employment of thermal insulators on the upper surface of metal. In order to ascertain the effects of these two factors on the structure refinement by the ECP technique, three groups of experiments were performed with different types of electrodes or various thermal insulators. By the comparison between solidification structures under different conditions, it is followed that the electrode and the thermal insulator have an obvious influence on the grain refinement under an applied ECP, and further analysis demonstrates that the thermal conditions of the liquid surface play a vital role in the modification of solidification structure. Also, the results support the viewpoint that most of the equiaxed grains originate from the liquid surface subjected to an ECP.

High efficiency, Site-specific Transfection of Adherent Cells with siRNA Using Microelectrode Arrays (MEA)

The discovery of RNAi pathway in eukaryotes and the subsequent development of RNAi agents, such as siRNA and shRNA, have achieved a potent method for silencing specific genes1-8 for functional genomics and therapeutics. A major challenge involved in RNAi based studies is the delivery of RNAi agents to targeted cells. Traditional non-viral delivery techniques, such as bulk electroporation and chemical transfection methods often lack the necessary spatial control over delivery and afford poor transfection efficiencies9-12. Recent advances in chemical transfection methods such as cationic lipids, cationic polymers and nanoparticles have resulted in highly enhanced transfection efficiencies13. However, these techniques still fail to offer precise spatial control over delivery that can immensely benefit miniaturized high-throughput technologies, single cell studies and investigation of cell-cell interactions. Recent technological advances in gene delivery have enabled high-throughput transfection of adherent cells14-23, a majority of which use microscale electroporation. Microscale electroporation offers precise spatio-temporal control over delivery (up to single cells) and has been shown to achieve high efficiencies19, 24-26. Additionally, electroporation based approaches do not require a prolonged period of incubation (typically 4 hours) with siRNA and DNA complexes as necessary in chemical based transfection methods and lead to direct entry of naked siRNA and DNA molecules into the cell cytoplasm. As a consequence gene expression can be achieved as early as six hours after transfection27. Our lab has previously demonstrated the use of microelectrode arrays (MEA) for site-specific transfection in adherent mammalian cell cultures17-19. In the MEA based approach, delivery of genetic payload is achieved via localized micro-scale electroporation of cells. An application of electric pulse to selected electrodes generates local electric field that leads to electroporation of cells present in the region of the stimulated electrodes. The independent control of the micro-electrodes provides spatial and temporal control over transfection and also enables multiple transfection based experiments to be performed on the same culture increasing the experimental throughput and reducing culture-to-culture variability. Here we describe the experimental setup and the protocol for targeted transfection of adherent HeLa cells with a fluorescently tagged scrambled sequence siRNA using electroporation. The same protocol can also be used for transfection of plasmid vectors. Additionally, the protocol described here can be easily extended to a variety of mammalian cell lines with minor modifications. Commercial availability of MEAs with both pre-defined and custom electrode patterns make this technique accessible to most research labs with basic cell culture equipment.

High efficiency, Site-specific Transfection of Adherent Cells with siRNA Using Microelectrode Arrays (MEA)

The discovery of RNAi pathway in eukaryotes and the subsequent development of RNAi agents, such as siRNA and shRNA, have achieved a potent method for silencing specific genes for functional genomics and therapeutics. A major challenge involved in RNAi based studies is the delivery of RNAi agents to targeted cells. Traditional non-viral delivery techniques, such as bulk electroporation and chemical transfection methods often lack the necessary spatial control over delivery and afford poor transfection efficiencies. Recent advances in chemical transfection methods such as cationic lipids, cationic polymers and nanoparticles have resulted in highly enhanced transfection efficiencies. However, these techniques still fail to offer precise spatial control over delivery that can immensely benefit miniaturized high-throughput technologies, single cell studies and investigation of cell-cell interactions. Recent technological advances in gene delivery have enabled high-throughput transfection of adherent cells, a majority of which use microscale electroporation. Microscale electroporation offers precise spatio-temporal control over delivery (up to single cells) and has been shown to achieve high efficiencies. Additionally, electroporation based approaches do not require a prolonged period of incubation (typically 4 hours) with siRNA and DNA complexes as necessary in chemical based transfection methods and lead to direct entry of naked siRNA and DNA molecules into the cell cytoplasm. As a consequence gene expression can be achieved as early as six hours after transfection. Our lab has previously demonstrated the use of microelectrode arrays (MEA) for site-specific transfection in adherent mammalian cell cultures. In the MEA based approach, delivery of genetic payload is achieved via localized micro-scale electroporation of cells. An application of electric pulse to selected electrodes generates local electric field that leads to electroporation of cells present in the region of the stimulated electrodes. The independent control of the micro-electrodes provides spatial and temporal control over transfection and also enables multiple transfection based experiments to be performed on the same culture increasing the experimental throughput and reducing culture-to-culture variability. Here we describe the experimental setup and the protocol for targeted transfection of adherent HeLa cells with a fluorescently tagged scrambled sequence siRNA using electroporation. The same protocol can also be used for transfection of plasmid vectors. Additionally, the protocol described here can be easily extended to a variety of mammalian cell lines with minor modifications. Commercial availability of MEAs with both pre-defined and custom electrode patterns make this technique accessible to most research labs with basic cell culture equipment.

Accelerated spheroidization induced by high intensity electric pulse in a severely deformed eutectoid steel

Application of high intensity electric pulse (HIEP) to a severely deformed eutectoid microstructure in high carbon steel wire has resulted in spheroidized microstructure. The observed spheroidization on electropulsing is compared with that reported for isothermal/thermo-mechanical annealing of the pearlite structure. The faster kinetics observed in this study has been rationalized in terms of accelerated kinetics induced by HIEP.

Rapid temporal control of transdermal drug delivery by electroporation.

Transdermal drug delivery has the potential to be a noninvasive. user-friendly method of delivering drugs at steady or time-varying rates ( 1.2). However, to date it has found limited clinical application. largely because transport of most drugs across human skin is very slow, exhibiting lag times of hours to days and steady-state rates which are often subtherapeutic. Recently, evidence for electroporation of skin has been demonstrated and proposed as a mechanism to enhance transdermal drug delivery (3-7). Electroporation involves the application of a brief electric field pulse which creates aqueous pathways in lipid hilayers. such as cell membranes (8-11). During electroporation, the electric field is believed to increase molecular transport dramatically by a combination of two mechanisms: 1) electropores are created and 2) as pores appear, molecules are rapidly moved through the pores by electrophoresis and/ or electroosmosis due to the local field. Electroporation of skin could have significance for drug delivery. having been shown to cause transdermal flux increases up to four orders of magnitude which are largely or fully reversible. possibly involving transient structural changes in the intercellular lipid bilayers of the stratum corneum (5.12). This study focuses on the rapid kinetics of transdermal transport by electroporation, which may allow rapid onset of therapeutic action and/or complex drug delivery profiles during transdermal drug delivery.

A Pockels cell electrofluorimeter

When anisodiametric macromolecules in solution are subjected to an electric field, they align. If fluorescent molecules are attached to them with some degree of structural order, this action is accompanied by changes in four polarized components of the fluorescence. An instrument is described which can measure the changes in all four components during the application of a single electric field pulse. The system incorporates a pair of Pockels cells which allow fast switching between the combination of polarization states of the incident and emitted beams. Measurements allow the determination of the angle between the axes of the fluorophore and the macromolecule. Representative results are presented for the binding angle between DNA and both proflavine and ethidium bromide using this arrangement.

Escherichia coli membranes during electrotransformation: an electron microscopy study

Structural changes undergone by Escherichia coli cell envelope membranes under the conditions of electrically induced gene (DNA) transfer (exponential pulse of about 13 kV/cm, τ = 5ms) were studied by freeze-fracture electron microscopy. Special device similar to that of Stenger and Hui (1986) J. Membr. Biol. 93, 43–53), that allowed cryofixation of samples almost simultaneously with application of electric pulse, was employed to examine the cells within a short time (⩽ 1 s) after the pulse. Extensive blebbing of cells was observed immediately after the pulse. At later times (30–40 s after the pulse) blebbing was not detected, instead infrequent cellular membrane fusion and formation of large membrane ‘openings’ or pores were observed. An attempt to relate the observed membrane changes with cellular viability and permeability to exogenous DNA failed. Challenge of cells with a plasmid DNA 10 s after the pulse application resulted in a dramatic loss (at least four orders of magnitude) of the number of transformants compared to cells pulsed in the presence of DNA. On the other hand the results on additional pulsing of cells prior to the main electrotransformation procedure suggested that the life-time of membrane defects is at least no less than 2 min. Possible ways to reconcile the results are suggested.