Low Voltage Pulse Research Articles

Improvement of the Tribological Properties of DLC/oxynitriding Duplex-treated AISI H13 Alloy Steel

In this study, diamond-like carbon (DLC) films were prepared by DC-pulsed plasma CVD after the oxynitride treatment of AISI H13 tool steel. In order to investigate the tribological properties of DLC films, a Raman spectroscopy analysis, wear test, adhesion and roughness tests were performed. The main parameters of the DC-pulsed plasma CVD process includes various pretreatment times of argon plasma (15, 30, 45 and 60 min). Experimental results showed that an oxynitride layer and the DLC films could be completely obtained after DLC/oxynitriding duplex treatment. The duplex coating layers had optimal adhesion (critical load reached to 10.65 N) and wear properties after DC-pulsed plasma was CVD treated via a low pulse voltage (–1.5 kV), pretreatment times of the argon plasma were 15 min and the substrate temperature was kept at 40°C. Meanwhile, the optimal DLC/oxynitriding duplex treated specimens possessed the lowest wear volume (2.25 × 10 –3 mm 3 ) and a lower friction coefficient (0.06).

High-performance organic nano-floating-gate memory devices based on graphite nanocrystals as charge-trapping elements and high-k Ta2O5 as a controlled gate dielectric

A new type of high-performance organic nano-floating-gate memory (NFGM) device has been fabricated by integrating graphite nanocrystals (GNCs) as charge-trapping elements and high-k Ta2O5 as a controlled gate dielectric. The GNC nano-floating-gates have a high density of charge trapping sites, and they are electrically separated enabling the reduction of stored charge leakage. With a relatively low-voltage programming pulse (−2 V, 1 μs), the fabricated devices exhibit a significant negative threshold voltage shift of 1.3 V, and programming/erasing switching times of less than 10 ns are observed. Furthermore, the NFGM devices show a long retention time of more than 10 years at room temperature along with robust endurance properties with 104 cycles of repeated programming/erasing. This approach provides an outstanding alternative approach for fabricating high-performance GNC-based organic NFGM devices and opens up a new route for the development of next-generation non-volatile memory devices.

Optimization of Electric Pulse Amplitude and Frequency In Vitro for Low Voltage and High Frequency Electrochemotherapy

During standard electrochemotherapy (ECT), using a train of 1,000V/cm amplitude rectangular pulses with 1Hz frequency, patients experience an unpleasant sensation and slight edema. According to the patients, muscle contractions provoked by high amplitude (about 1,000V/cm) and low repetition frequency (1Hz) pulses are the most unpleasant and painful sensations. Recently, ECT using low voltage and higher repetition frequency (LVHF) has been shown to be an effective tool for inhibiting tumor growth. The aim of the present study was to optimize electric pulse amplitude and repetition frequency for LVHF ECT by sampling the different sets of pulse parameters on cell viability and permeabilization. In ECT, a reversible effect based on high permeabilization is desirable. For this purpose, we used bleomycin to evaluate the permeabilization of K562 and MIA-PACA2 cells caused by low voltage (50-150V/cm) and higher repetition frequency (4-6kHz) electric pulses. We show that the reversible effect with electropermeabilization of the cells caused by LVHF ECT is accessible; this interaction is more effective for electric pulses with 70V/cm amplitude.

Manipulation at a distance: Atomic-scale observation of ballistic electron transport in single layer graphene

We present scanning tunneling microscopy manipulation experiments on epitaxial graphene and the carbon buffer layer grown on hexagonal silicon carbide. Low voltage pulses applied to the graphene layer with the microscope tip induce nonlocal modifications of a bare carbon buffer region 10 nm away. The graphene itself is not affected. This is direct evidence for ballistic hot electrons propagating along the graphene layer to the graphene edge. High energy states in the graphene band structure (Van Hove Singularities) may explain both the electron transport and the coupling of the graphene edge to the adjacent bare carbon buffer region.

Study of superradiance based on a low-voltage backward wave oscillator

According to the small size requirement for wide-band high-power microwave radiation, a superradiance backward wave oscillator (BWO) is proposed to generate such high-power microwave radiation with a low voltage (∼20 kV) pulse power supply and low guiding magnet field (∼0.1 T). In order to get a high-efficiency C-band superradiance BWO with a low beam voltage and a low guiding magnet field, the mechanism of superradiance in a BWO is explored in particle-in-cell simulation. With the oversized structure, the simulation shows that a microwave power of 405 kW with a frequency of 5.6 GHz and a spectrum width of 500 MHz can be obtained with a voltage of 23 kV and magnetic field of 0.1 T.

A FET Structure Field Emission Device With High-Speed Pulse Signal Control

In this letter, a current driving method by using a field-effect transistor (FET)-modulated structure for a carbon-nanotube field emission device (FED) is reported. This device can obtain a stable large emission current modulated value by tunneling the gate voltage of the metal-oxide-semiconductor FET, i.e., from 2 to 128 μA (the anode voltage is 1000 V). Moreover, a subpixel FED and a periphery circuit are also designed. This device can dramatically produce a working pulse emission current (peak current: 350 μA) by controlling a low-voltage high-speed pulse signal (peak: 22.5 V). Compared with the previous triode FEDs, this FET-modulated device has more advantages in driving circuit design. If the integrated process for this device can be realized, it will promote the FED's application to launch on the market.

Voltage Preconditioning Allows Modulated Gene Expression in Neurons Using PEI-complexed siRNA

We present here a high efficiency, high viability siRNA-delivery method using a voltage-controlled chemical transfection strategy to achieve modulated delivery of polyethylenimine (PEI) complexed with siRNA in an in vitro culture of neuro2A cells and neurons. Low voltage pulses were applied to adherent cells before the administration of PEI-siRNA complexes. Live assays of neuro2a cells transfected with fluorescently tagged siRNA showed an increase in transfection efficiency from 62 ± 14% to 98 ± 3.8% (after −1 V). In primary hippocampal neurons, transfection efficiencies were increased from 30 ± 18% to 76 ± 18% (after −1 V). Negligible or low-level transfection was observed after preconditioning at higher voltages, suggesting an inverse relationship with applied voltage. Experiments with propidium iodide ruled out the role of electroporation in the transfection of siRNAs suggesting an alternate electro-endocytotic mechanism. In addition, image analysis of preconditioned and transfected cells demonstrates siRNA uptake and loading that is tuned to preconditioning voltage levels. There is approximately a fourfold increase in siRNA loading after preconditioning at −1 V compared with the same at ±2–3 V. Modulated gene expression is demonstrated in a functional knockdown of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) in neuro2A cells using siRNA. Cell density and dendritic morphological changes are also demonstrated in modulated knockdown of brain derived neurotrophic factor (BDNF) in primary hippocampal neurons. The method reported here has potential applications in the development of high-throughput screening systems for large libraries of siRNA molecules involving difficult-to-transfect cells like neurons.

Phase Transformation Experimental and Theoretical Study of Micro-power Generator Supplying Source for IC Chip Based on Ferroelectric Ceramic

We demonstrated both experimentally and in theory analysis and calculation that the PSZT ferroelectric ceramic generator system can perform as a micro power supplying source for IC chip. The ceramic phase transition under transverse shock wave compression can charge external storage capacitor. The ferroelectric micro pulsed power system is capable of generating low output voltage pulses with amplitudes 50.3 V and with transferred energy 1.12 mJ, and supplying IC chip with micro power sources. We developed the methodology for theory analysis and experimental operation of the ferroelectric generator. The experimental results were in good agreement with the theory analysis.

Effect of Low-voltage Pulse on Cell Elimination

Abstract The low electric field application to HeLa cells adhered to electrodes was studied to induce cell death effectively. The low-voltage pulse applied to the electrode was generated with charge and discharge by an originally made circuit. The unique characteristics in this experiment is the charge flow between electrodes, and it causes direct attack of the ions to the cell membrane, leading to complete cell elimination. Viability of cells appreciably decreased with increase in discharge time at a quite low 3 V cm−1 that has not been reported to date.

Nursing of low-voltage pulse generator as a therapy for Meniere disease

Objective To explore the nursing methods low-voltage pulse generator as a therapy for Meniere disease.Methods Totals of 30 cases with refractory,active Meniere disease were selected and treated with grommet insertion plus low-voltage pulse generator between August 2005 and June 2010.Before operation,patients were received psychological care and drugs guidance,operation preparation and took laboratory tests.After operation,vital signs and complications were observed,especially anti-infection,prevention of tube wentaway,and guidance of self-care after discharge and followed up were gave by nurses.Results After therapy,the degree and frequency of vertigo of patients were significantly relieved in the 4th and 8th week than before therapy.No nursing complications occurred in these 30 cases after discharge 8 weeks.Conclusions Carefully nursing can improve the incidence of complication,and promote the therapy effect of low-voltage pulse generator for Meniere disease. Key words: Meniere disease; Nursing; Grommet insertion; Low-voltage pulse generator

Electric Field Orientation for Gene Delivery Using High-Voltage and Low-Voltage Pulses

Electropermeabilization is a biological physical process in response to the presence of an applied electric field that is used for the transfer of hydrophilic molecules such as anticancer drugs or DNA across the plasma membranes of living cells. The molecular processes that support the transfer are poorly known. The aim of our study was to investigate the effect of high-voltage and low-voltage (HVLV) pulses in vitro with different orientations on cell permeabilization, viability and gene transfection. We monitored the permeabilization with unipolar and bipolar HVLV pulses with different train repetition pulses, showing that HVLV pulses increase cell permeabilization and cell viability. Gene transfer was also observed by measuring green fluorescent protein (GFP) expression. The expression was the same for HVLV pulses and electrogenotherapy pulses for in vitro experimentation. As the viability was better preserved for HVLV-pulsed cells, we managed to increase the number of GFP-expressing cells by up to 65% under this condition. The use of bipolar HVLV train pulses increased gene expression to a higher extent, probably by affecting a larger part of the cell surface.

In Vivo Molecular Imaging and Histological Analysis of Changes Induced by Electric Pulses Used for Plasmid DNA Electrotransfer to the Skin: A Study in a Dorsal Window Chamber in Mice

Electropermeabilization/electroporation (EP) is a physical method that by application of electric pulses to cells increases cell membrane permeability and enables the introduction of molecules into the cells. One of the uses of EP in vivo is plasmid DNA electrotransfer to the skin for DNA vaccination. EP of tissues induces reduction of blood flow and, in combination with plasmid DNA, induction of an immune response. One of the EP protocols for plasmid DNA electrotransfer to the skin is a combination of high-voltage (HV) and low-voltage (LV) pulses. However, the effects of this pulse combination on skin-vessel blood flow are not known. Therefore, using intravital microscopy in a dorsal window chamber in mice and fluorescently labeled dextrans, the effects of one HV and eight LV pulses on skin vasculature were investigated. In addition, a detailed histological analysis was performed. Image analysis of fluorescence intensity changes demonstrated that EP induces a transient constriction and increased permeability of blood vessels as well as a “vascular lock.” Histological analysis revealed rounding up of endothelial cells and stacking up of erythrocytes at 1 h after EP. In addition, extravasation of erythrocytes and leukocyte infiltration accompanied by edema were determined up to 24 h after EP. In conclusion, our results show that blood flow modifying effects of EP in skin contribute to the infiltration of immune cells in the exposed area. When combined with plasmid DNA for vaccination, this could enable the initial and prolonged contact of immune cells with encoded therapeutic proteins.

Low Voltage and Low Power Pulse Flip-Flops in Nanometer CMOS Processes

Low Voltage and Low Power Pulse Flip-Flops in Nanometer CMOS Processes

Low voltage irreversible electroporation induced apoptosis in HeLa cells

High-voltage electric field pulses can make cell membrane electroporated irreversibly and eliminate malignant cells via necrosis. However, low-voltage is not efficient as that. This study determined the differential effects of high- and low-voltage electric field pulses on HeLa cells, when the power of low-voltage was enhanced by increasing quantity of pulses. Pulses electric fields with permanent frequency (1 Hz) and pulse length (100 μs) were performed on HeLa cells. Voltage and pulse sets (8 pulses/set) were various during treatment. CCK-8 assay was used to detect cell viability. The quantitative determination of apoptosis and necrosis were performed by flow cytometry with Annexin V and PI staining. Transmission electron microscopy was used to observe the ultrastructure of HeLa cells. Caspase-3 and caspase-8, the enzymes in apoptotic pathway, were determined by western blot. The data showed that low-voltage electric field pulses also could make cell irreversible electroporation (IRE) and ablate HeLa cells effectively by induction of apoptosis. The ablating effect due to low-voltage treatments delivered with a greater number of pulses may be as satisfactory as high-voltage, or even preferable because it causes less necrosis and more apoptosis. IRE induced by low voltage with more pulses could ablate HeLa cells effectively as high voltage, and it was preferable that less necrosis and more apoptosis occurred under such condition.

Effects of a low-voltage electric pulse charged to culture soil on plant growth and variations of the bacterial community

This study was conducted to verify the effect of an electric pulse on growth of crops (lettuce and hot pepper) that were cultivated in lab-scale soil. The electric pulse generated from direct-circuited 2, 4, 6, 8, and 10 V of electricity by periodic exchange of the anode and cathode was charged to a culture soil that is an electrically pulsed culture soil (EPCS) but not charged to a conventional culture soil (CCS). Growth of lettuce increased and growth duration of hot pepper plants was more prolonged at 4, 6, 8, and 10 V of EPCS than at 2 V of EPCS and CCS. The fruiting duration and yield of hot pepper fruits were proportional to the growth duration of the hot pepper plants. Temperature gradient gel electrophoresis (TGGE) patterns of 16S-rDNA obtained from the bacterial community inhabiting the CCS and EPCS were identical at the initial time and did not change significantly at days 28 and 56 of cultivation. The bacterial communities inhabiting the surface of lettuce roots were not influenced by the electric pulse but were significantly different from those inhabiting the culture soil based on the TGGE patterns. Growth of lettuce and hot pepper plants that were cultivated in 4 - 10 V of EPCS may increase; however, the bacterial community inhabiting the soil and the surface of plant roots may not be influenced by an electric pulse.

Gene Suppression of Mouse Testis In Vivo Using Small Interfering RNA Derived from Plasmid Vectors

We evaluated whether inhibiting gene expression by small interfering RNA (siRNA) can be used for an in vivo model using a germ cell-specific gene (Tex101) as a model target in mouse testis. We generated plasmid-based expression vectors of siRNA targeting the Tex101 gene and transfected them into postnatal day 10 mouse testes by in vivo electroporation. After optimizing the electroporation conditions using a vector transfected into the mouse testis, a combination of high- and low-voltage pulses showed excellent transfection efficiency for the vectors with minimal tissue damage, but gene suppression was transient. Gene suppression by in vivo electroporation may be helpful as an alternative approach when designing experiments to unravel the basic role of testicular molecules.

Effect of radiofrequency assisted freezing on meat microstructure and quality

The potential exploitation of radiofrequency (RF) to assist food freezing was studied. To this aim, freezing of pork meat was performed in a RF pilot equipment modified to allow food immersion in a liquid nitrogen spray. During freezing, pulsed RF treatments were applied (RF assisted cryogenic freezing). Freezing under cryogenic fluid flow (cryogenic freezing) and air freezing were also performed as controls. Results showed that RF assisted freezing is possible by using low voltage pulses (2kV). The thawing losses of RF cryogenic frozen meat were much lower than that observed during thawing of air and cryogenic frozen meat, which showed similar drip loss. The analyses carried out on the microstructure of meat showed that the tissue exhibited a better cellular structure when RF was applied. Much less intercellular voids and cell disruption were observed. As compared to the control sample, RF frozen meat presented smaller ice crystals, which were mainly located at intracellular level. This was attributed to the ability of RF to depress the freezing point thus producing more nucleation sites.

Calcium influx determines the muscular response to electrotransfer

Cell membrane permeabilization by electric pulses (electropermeabilization), results in free exchange of ions across the cell membrane. The role of electrotransfer-mediated Ca(2+)-influx on muscle signaling pathways involved in degeneration (β-actin and MurF), inflammation (IL-6 and TNF-α), and regeneration (MyoD1, myogenin, and Myf5) was investigated, using pulse parameters of both electrochemotherapy (8 HV) and DNA delivery (HVLV). Three pulsing conditions were used: 8 high-voltage pulses (8 HV), resulting in large permeabilization and ion flux, and a combination of one high-voltage pulse and one low-voltage pulse (HVLV), either alone or in combination with injection of DNA. Mice and rats were anesthetized before pulsing. At the times given, animals were killed, and intact tibialis cranialis muscles were excised for analysis. Uptake of Ca(2+) was assessed using (45)Ca as a tracer. Using gene expression analyses and histology, we showed a clear association between Ca(2+) influx and muscular response. Moderate Ca(2+) influx induced by HVLV pulses results in activation of pathways involved in immediate repair and hypertrophy. This response could be attenuated by intramuscular injection of EGTA reducing Ca(2+) influx. Larger Ca(2+) influx as induced by 8-HV pulses leads to muscle damage and muscle fiber regeneration through recruitment of satellite cells. The extent of Ca(2+) influx determines the muscular response to electrotransfer and, thus, the success of a given application. In the case of electrochemotherapy, in which the objective is cell death, a large influx of Ca(2+) may be beneficial, whereas for DNA electrotransfer, muscle recovery should occur without myofiber loss to ensure preservation of plasmid DNA.

Effect of Low-Voltage Electric Current Pulse on Semi-Solid Microstructure of Magnesium Alloy AZ91D

The effect of discharging cycle, voltage, capacitance and time on solidified microstructure of semi-solid slurry of AZ91D alloy treated with Low-Voltage Electric Current Pulse(LVECP) was investigated in this paper. The experimental results show that primary grains of AZ91D alloy were refined apparently, the morphology dendrites of α-Mg were changed by electric current pulse and the nondendritic structure of semi-solid slurry of AZ91D alloy could be obtained with appropriate processing parameters. The decrease of discharging cycle and the increase of discharging voltage and time to prepare semisolid slurry by LVECP discharge promotes the formation of fine α-Mg grains. It is proposed that LVECP treatment created a new dynamic factor for nucleation so that the number of nuclei increased, which restrained the formation of large primary α-Mg dendrites and created a base to form spherical crystals of primary α-Mg. The stronger temperature fluctuation in the melt with many rosette primary α-Mg caused by LVECP discharge and the remelting of the secondary arm roots in the same time are the most important reasons for formation of spherical primary α-Mg grains.

Efferent Fibers Innervate Gustatory and Mechanosensitive Afferent Fibers in Frog Fungiform Papillae

A possibility of efferent innervation of gustatory and mechanosensitive afferent fiber endings was studied in frog fungiform papillae with a suction electrode. The amplitude of antidromic impulses in a papillary afferent fiber induced by antidromically stimulating an afferent fiber of glossopharyngeal nerve (GPN) with low voltage pulses was inhibited for 40 s after the parasympathetic efferent fibers of GPN were stimulated orthodromically with high voltage pulses at 30 Hz for 10 s. This implies that electrical positivity of the outer surface of papillary afferent membrane was reduced by the efferent fiber-induced excitatory postsynaptic potential. The inhibition of afferent responses in the papillae was blocked by substance P receptor blocker, L-703,606, indicating that substance P is probably released from the efferent fiber terminals. Slow negative synaptic potential, which corresponded to a slow depolarizing synaptic potential, was extracellularly induced in papillary afferent terminals for 45 s by stimulating the parasympathetic efferent fibers of GPN with high voltage pulses at 30 Hz for 10 s. This synaptic potential was also blocked by L-703,606. These data indicate that papillary afferent fiber endings are innervated by parasympathetic efferent fibers.