Application Of Electric Current Research Articles

Reversible Wetting−Dewetting Transitions on Electrically Tunable Superhydrophobic Nanostructured Surfaces

In this work, electrically controlled fully reversible wetting-dewetting transitions on superhydrophobic nanostructured surfaces have been demonstrated. Droplet behavior can be reversibly switched between the superhydrophobic Cassie-Baxter state and the hydrophilic Wenzel state by the application of electrical voltage and current. The nature of the reversibility mechanism was studied both experimentally and theoretically. The reported results can provide a new method of dynamically controlling liquid-solid interactions.

Electrically Assisted Ocular Gene Therapy

Electrotransfer and iontophoresis are being developed as innovative non-viral gene delivery systems for the treatment of eye diseases. These two techniques rely on the use of electric current to allow for higher transfection yield of various ocular cell types in vivo. Short pulses of relatively high-intensity electric fields are used for electrotransfer delivery, whereas the iontophoresis technique is based on the application of low voltage electric current. The basic principles of these techniques and their potential therapeutic application for diseases of the anterior and posterior segments of the eye are reviewed. Iontophoresis has been found most efficient for the delivery of small nucleic acid fragments such as antisense oligonucleotides, siRNA, or ribozymes. Electrotransfer, on the other hand, is being developed for the delivery of oligonucleotides or custom designed plasmids. The wide range of strategies already validated and the potential for targeting specific types of cells confirm the promising early observations made using electrotransfer and iontophoresis. These two nonviral delivery systems are safe and can be used efficiently for targeted gene delivery to ocular tissues in vivo. At the present, their application for the treatment of ocular human diseases is nearing its final stages of adaptation and practical implementation at the bedside.

Prevention of pin tract infection in external stainless steel fixator frames using electric current in a goat model

Pin tract infections of external fixators used in orthopaedic reconstructive bone surgery are serious complications that can eventually lead to periostitis and osteomyelitis. In vitro experiments have demonstrated that bacteria adhering to stainless steel in a biofilm mode of growth detach under the influence of small electric currents, while remaining bacteria become less viable upon current application. Therefore, we have investigated whether a 100 μA electric current can prevent signs of clinical infection around percutaneous pins, implanted in the tibia of goats. Three pins were inserted into the lateral right tibia of nine goats, of which one served for additional frame support. Two pins were infected with a Staphylococcus epidermidis strain of which one pin was subjected to electric current, while the other pin was used as control. Pin sites were examined daily. The wound electrical resistance decreased with worsening of the infection from a dry condition to a purulent stage. After 21 days, animals were sacrificed and the pins taken out. Infection developed in 89% of the control pin sites, whereas only 11% of the pin sites in the current group showed infection. These results show that infection of percutaneous pin sites of external fixators in reconstructive bone surgery can be prevented by the application of a small DC electric current.

The impact of electrical current, mechanical bending, and thermal annealing on tin whisker growth

This paper presents the results of an eight-month design-of-experiment assessment of whisker growth on bright and matte tin-plated copper, mechanically deformed and unformed coupons, subject to a continuous 50 °C/50%RH environment, with and without the presence of a constant electrical current density magnitude of 0.48 × 10 2 A/cm 2. Whiskers were observed to grow both at the anode and cathode end. The distribution-based data showed a reduction in whisker density due to annealing and/or the application of electrical current for both bright and matte tin. However, the application of electrical current was observed to increase the standard deviation of the length distribution, and to generate longer whiskers.

Assembled cation‐exchange/anion‐exchange polypyrrole layers as new simplified artificial muscles

AbstractA simplified artificial muscle has been constructed by assembling different polypyrrole structures in the same synthesis process. This produces not only “all‐polymeric” but rather a new generation of “all‐conducting‐polymer” artificial muscles, capable of moving in electrolytic media by an electrical current application with no evidence of delamination after several cycles. Suitable devices can be constructed for biomedical applications, based on this conducting polymer film. Copyright © 2006 John Wiley & Sons, Ltd.

Interferential Therapy Produces Antinociception During Application in Various Models of Inflammatory Pain

Although interferential therapy (IFT) is used widely in the management of many painful conditions, the effectiveness and the mechanism of action of IFT in animal models of inflammatory pain have not been evaluated. The aim of this study was to evaluate the effectiveness of IFT in reducing inflammatory pain and edema in rats. Sixty-nine male Wistar rats were used in the study. The effect of IFT application (4,000-Hz carrier frequency, 140-Hz amplitude-modulated beat frequency, pulse duration=125 milliseconds, current intensity=5 mA) for 1 hour on the formalin-induced nociceptive response and edema and on carrageenan-induced mechanical hyperalgesia and edema was evaluated. Interferential therapy significantly reduced the formalin-evoked nociceptive response when applied to the paw immediately after but not before the formalin injection. Interferential therapy application at 2 hours after the carrageenan injection significantly prevented a further increase in carrageenan-induced mechanical hyperalgesia only immediately after discontinuation of the electrical current application. The antinociception induced by IFT was not attributable to a reduction in inflammation because IFT did not significantly reduce the edema induced by either formalin or carrageenan. The results suggest that, despite its short-duration effect, IFT is effective in reducing inflammatory pain and should be considered primarily for use in the control of acute inflammatory pain.

放電プラズマ焼結された過共晶Ａｌ‐Ｓｉ合金の微細空孔形成と機械的性質

The samples were fabricated with various conditions in spark plasma sintering (SPS) by using a rapidly solidified powder of a hypereutectic Al-16%Si alloy. Micro-pores and Si particles were investigated metallographically, and density and Vickers hardness were estimated. As a result, micro-pores were randomly distributed in the sample preheated under a pressure before SPS but they were distributed like network along powder particles after a higher electric current application of SPS. The density decreased as electric current of SPS increased. The size and volume fraction of Si particle increased, while Vickers hardness decreased as the electric current of SPS increased. A part of the decrease in hardness is considered to be caused by particle dispersion hardening mechanism.

Transdermal iontophoresis

Iontophoresis is a technique used to enhance the transdermal delivery of compounds through the skin via the application of a small electric current. By the process of electromigration and electro-osmosis, iontophoresis increases the permeation of charged and neutral compounds, and offers the option for programmed drug delivery. Interest in this field of research has led to the successful delivery of both low (lidocaine) and high molecular drugs, such as peptides (e.g., luteinising hormone releasing hormone, nafarelin and insulin). Combinations of iontophoresis with chemical enhancers, electroporation and sonophoresis have been tested in order to further increase transdermal drug permeation and decrease possible side effects. In addition, rapid progress in the fields of microelectronics, nanotechnology and miniaturisation of devices is leading the way to more sophisticated iontophoretic devices, allowing improved designs with better control of drug delivery. Recent successful designing of the fentanyl E-TRANS® iontophoretic system have provided encouraging results. This review will discuss basic concepts, principles and applications of this delivery technique.

Electrically tunable superhydrophobic nanostructured surfaces

In this work, we discuss dynamic electrical control of the wetting behavior of liquids on nanostructured surfaces spanning the entire possible range from superhydrophobic behavior to nearly complete wetting. It is demonstrated that a droplet of liquid can be reversibly switched between the superhydrophobic “rolling ball” state and the hydrophilic immobile droplet state by the application of electrical voltage and current. The nature of the transition mechanism is studied both experimentally and theoretically. The reported results provide novel methods of manipulating liquids at microscale.

Electrodialytic removal of heavy metals from municipal solid waste incineration fly ash using ammonium citrate as assisting agent

Electrodialytic remediation, an electrochemically assisted separation method, has previously shown potential for removal of heavy metals from municipal solid waste incineration (MSWI) fly ashes. In this work electrodialytic remediation of MSWI fly ash using ammonium citrate as assisting agent was studied, and the results were compared with traditional batch extraction experiments. The application of electric current was found to increase the heavy metal release significantly compared to batch extraction experiments at comparable conditions (same liquid-to-solid ratio, same assisting agent, and same extraction time). Up to 86% Cd, 20% Pb, 62% Zn, 81% Cu and 44% Cr was removed from 75 g of MSWI fly ash in electrodialytic remediation experiments using ammonium citrate as assisting agent. The time range for the experiments varied between 5 and 70 days.

An Experimental Study on Applicability of Passive Electric Potential CT Method to Identification of Three-dimensional Surface Crack

This paper examines the applicability of passive electric potential CT (computed tomography) method to the quantitative identification of three-dimensional crack in structures. In this method, piezoelectric film is glued on the surface of structures. Electric potential values on the piezoelectric film change due to the strain distribution on the surface of structures, when the structure is subjected to external load. The strain distribution induces an electric potential distribution on the piezoelectric film. Then, this method does not require electric current application, and passively observed electric potential values on piezoelectric film can be used for the crack identification. The electric potential distribution on piezoelectric film was investigated numerically and experimentally. It was found that the electric potential distribution shows the characteristic change corresponding to the shape of the surface crack. An inverse method based on the least residual method was applied to the crack identification from the electric potential distribution. In this inverse method, square sum of residuals is evaluated between the measured electric potential distributions and those computed from electric potential distribution of the piezoelectric film. Three-dimensional surface crack were identified from measured electric potential distribution. It was found that location and size of the crack can be quantitatively estimated by using two-dimensional distribution of electric potential.

Effect of direct electric current on microbiological quality of white croaker (Micropogonias furnieri)

White croaker (Micropogonias furnieri) were submitted to a direct electric current post-mortem and stored refrigerated at 4°C for 16 days. Flesh and surface of electrically treated fish exhibited higher mesophilic bacteria counts than controls on the 3rd and on the 6th day of storage, respectively. Conversely, electrical treatment reduced flesh and surface psychrotrophic bacteria counts on the 12th and on the 16th day of storage, respectively. These changes had no influence on fish shelf life since they occurred when microbial counts were higher than the recommended limit for human consumption. Electrical treatment significantly reduced total count of mesophilic but did not affect psychrotrophic bacteria in the water used in fish treatment. These results suggest that although post-mortem application of electric current does not increase fish shelf life, it may reduce microbial counts in the water used in fish processing.

Microstructural evolution of copper thin films by applied electrical current flow

The microstructural evolution during electrical current flow application on copper thin films was studied. The morphological analysis by atomic force microscopy (AFM), and the structural analysis by grazing incidence X-ray diffraction (XRD) were realized when an electrical current between 0 and 2.2A was applied in situ on films by means of electrodes located on films. Positions of peaks diffraction of the asdeposited film were found to be larger than the 20 copper standard value, with a further decrement with the applied current. Cuprite (Cu 2 O) is formed when the current is hold for longer times and/or when high current values are applied, favouring the oxidation process. Morphological images show that grain size is modified when the current is applied; meanwhile the rms-rugosity, initially diminishes and after that, increases due to the high current values forming Cu 2 O on surface. Copper oxidation was studied by Auger spectroscopy and XRD.

Electrochemical decolourisation of structurally different dyes

The electrochemical decolourisation of structurally different dyes (bromophenol blue, indigo, poly R-478, phenol red, methyl orange, fuchsin, methyl green and crystal violet) by means of the application of DC electric current was assessed. It was found that the electrochemical process allowed a colour removal of all dyes studied, although the decolourisation rate largely depended on the chemical structure of the different dyes. Nearly complete decolourisation was achieved for bromophenol blue followed by methyl orange and methyl green, whereas phenol red was hardly decolourised (30% in 60 min). In mixtures of two dyes, the decolourisation rate became similar for both dyes. However, the addition of a redox mediator, (Co 2+/3+) clearly enhanced the degradation rate of all tested dyes, but the simplest dye molecules were attacked firstly, followed by dyes with more complex chemical structures. The results revealed the suitability of the process to effectively decolourise wastewaters from dyeing process.

Materials and Process Development of Advanced Refractories for Innovative Metal Processing

Improved structures of MgO carbon bonded materials due to new binder systems and due to the application of electrical currents during operation have been achieved for advanced applications in the secondary metallurgy and during near net shape metal casting.

LFZ fibre texture modification induced by electrical polarization

Preliminary results of electric current flux application during LFZ growth of BSCCO fibres show a dramatic effect on fibre texture. The solute electromigration modifies the ionic transport and consequently the phase development, inducing a randomly crystal orientation on the as-grown fibres. After heat treatment, fibres grown with reverse electric current are three times more resistive at room temperature than those without current, although presenting a narrower transition to the superconducting state.

Electrical field freezing effect on laser floating zone (LFZ)-grownBi2Sr2Ca2Cu4O11 superconducting fibres

The electrical assisted laser floating zone (EALFZ) solidification process makes thetailoring of fibre microstructures possible. The application of a dc electrical current of during the solidification process ofBi2Sr2Ca2Cu4O11 nominal composition fibres strongly modified phase development, crystal shapes and effectivedistribution coefficients. Growth conditions with the solidification interface positively polarizeddeviate the system from metastability, leading to the development of the equilibrium cuprate(SrxCa1−x)14Cu24O41 (14/24) as primary phase dendrites. Compared to the morphology of theSrxCa1−xCuO2 (1/1) primary crystals of the conventional LFZ process, the 14/24 crystals are alignedhigher along the fibre axis, with half the thickness and twice the extension. One of themajor effects of EALFZ is the control of the effective distribution coefficients,k. At equal values ofthe fibre pulling rate, R, the copper partition between the liquid and the solid is the most affected, thekCu increasing from 1 to 1.22 due to the ionic drift from the zone melt to the negative polarizedfeed rod. Bismuth and calcium effective distribution coefficients present the lowest values(kBi = 0.69 and kCa = 1.13) in these conditions, according to the field-modified BPS theory. When the reverse currentis applied, the dendritic morphology disappears and a globular structure of completely newphases develops.

Passive electric potential CT method using piezoelectric material for crack identification

When the piezoelectric film is glued on the surface of a cracked material subjected to mechanical load, change in electric potential distribution is observed on the surface of the film. Based on this phenomenon, the passive electric potential CT (computed tomography) method can be developed, which does not require electric current application for identifying cracks. This method may be applied to develop an intelligent structure with a function of self-monitoring of flaws and defects. For the crack identification from electric potential distribution, an inverse method based on the least residual method was applied, in which square sum of residuals are evaluated between the measured electric potential distributions and those computed by using the finite element method. Numerical simulations were carried out on identification of a through-thickness transverse crack. It was found that the location and size of the crack can be quantitatively identified by the proposed passive electric potential CT method.

Enhanced biotransformations and product recovery in a membrane bioreactor through application of a direct electric current

The simultaneous enhancement of biotransformation coupled to product recovery, purification and concentration is presented. The nitrilase of Rhodococcus rhodochrous LL100-21 catalyses the single-step hydrolytic biotransformation of benzonitrile to benzoic acid and ammonia. When a direct electric current is applied across a bioreactor containing the bacterium and benzonitrile, the charged product (benzoic acid) can be removed in situ across an anion exchange membrane and recovered in a separate compartment. Over the course of a 24-hour biotransformation, benzonitrile was converted to benzoic acid which was completely removed from the bioreactor chamber and concentrated 3-fold in a separate chamber. The rate of production of benzoic acid increased by 42% when the current was applied (0.044 mmol/min/g dry cell weight in the presence of current as compared to 0.03 mmol/min/g dry cell weight in its absence). The enhanced reaction rate was achieved irrespective of product separation and therefore appears to be a direct effect upon the bacterial cells. This process has potential for enhanced productivity from biotransformations through a simultaneous increase in metabolic activity and in situ product recovery.

Iontophoresis: from the lab to the bed side

Pioneer work on iontophoresis undertaken by David Maurice during the 1970s and 1980s laid the initial groundwork for its potential implementation as a promising ocular therapeutic modality. A better understanding of tissue interactions within the eye during electric current application, along with better designs of drug delivery devices have enabled us to pursue David Maurice's original ideas and take them from the bench to the bed side. In the present study we demonstrate the potential application of an iontophoresis device (Eyegate, Optis, France) for the treatment of certain human eye diseases. Seventeen patients received a penetrating keratoplasty (PKP) at various intervals before presentation with active graft rejection in our clinic and were treated using this iontophoresis device. Methylprednisolone sodium succinate (MP) 62·5 mg/ml was infused within the Eyegate ocular probe container and an electrical current of 1·5 mA was delivered for 4 min with the negative pole connected to the ocular probe. Patients were treated on an ambulatory basis and received a standard course of three iontophoresis applications given once a day over 3 consecutive days. After treatment, 15 of the 17 treated eyes (88%) demonstrated a complete reversal of the rejection processes. In two eyes, only a partial and temporary improvement was observed. The mean best corrected visual acuity of all 17 patients during the last follow up visit was 0·37±0·2 compared to 0·06±0·05 before initiation of the iontophoresis treatment. The mean follow-up time was 13·7 months with a range of 5–29 months for the 17 patients. No significant side-effects associated with the iontophoresis treatment were observed. Thus, for the management of active corneal graft rejection, iontophoresis of MP can be an alternative to very frequent instillations of eye drops, or to pulsed intravenous therapy of corticosteroids.