Monopolar Electrode Research Articles

Boosting BOD/COD biodegradability of automobile service stations wastewater by electrocoagulation

ABSTRACT This study investigates the application of electrocoagulation for enhancing the biodegradability of organic matter in automobile service station wastewater, notorious for its contamination with polyaromatic hydrocarbons, heavy metals, and surfactants. Optimization of key variables such as electrode material, current density, and electrical consumption is conducted, with correlation analysis assessing their impact on water quality. Experimental setups utilize a vertical configuration comprising eight monopolar steel electrode plates as cathodes and eight counter electrodes (either iron or aluminum) connected in parallel. Results indicate that employing iron as the sacrificial electrode significantly increases the biochemical oxygen demand/chemical oxygen demand (BOD/COD) ratio, highlighting the efficacy of heightened power levels in enhancing organic matter degradation. Optimal removal efficiencies, including 87.5 for COD, 96.01 for BOD, and 92.2% for total solids, are achieved at a current density of 42 A/m2 and energy consumption of 360 kWh/m3, while maintaining pH levels between 6 and 9. The findings underscore the potential of electrocoagulation with Fe, Al as anodes, and stainless-steel cathodes as an efficient wastewater treatment approach, particularly for COD, BOD, and solid particle removal, thus contributing significantly to environmental sustainability.

Performance of combined organic precipitation, electrocoagulation, and electrooxidation in treating anaerobically treated palm oil mill effluents

Palm oil mill effluent (POME), wastewater generated from palm oil production, is known for its extremely high chemical oxygen demand and brownish color. Anaerobic digestion is the primary treatment method for POME in the palm oil industry; however, anaerobically treated POME has high concentrations of residual contaminants and color intensity. This study proposes an approach to treat anaerobically-treated POME in recycled water for industrial applications by integrating preliminary organic precipitation, electrocoagulation, and electrooxidation (EO). The EO process was optimized in terms of the current density, electrolysis time, electrode arrangement, and feed flow rate. At a current density of 60 mA/cm2 and an electrolysis time of 9 min, the EO process with a graphite anode and stainless-steel cathode in the monopolar electrode configuration reduced the phenolic concentration and color in the preliminary-treated POME from 8.95 mg/L and 317.19 ADMI to 0.25 mg/L and 26.10 ADMI, respectively. Additionally, the EO process exhibited a 92.26% efficiency in lowering the ammonium-nitrogen content.

Gaussianity Evaluation of HD-sEMG Signals with Aging and Sex During Low and Moderate Isometric Contractions of the Biceps Brachii

IntroductionAging is associated with muscle decline, which alters both functional and anatomical properties of the neuromuscular system. These modifications can be reflected in high-density surface electromyography (HD-sEMG) signals. This study examines how age and sex impact the shape of the amplitude Probability Density Function (PDF) of HD-sEMG signals. Materials and MethodsMonopolar HD-sEMG signals were collected from the Biceps Brachii in a cohort of 17 individuals: 10 women (mean age: 22.9 ± 3.6 years) and 7 men (mean age: 24.4 ± 2.5 years) in the younger group, and 10 women (mean age: 69.8 ± 4.8 years) and 7 men (mean age: 72.8 ± 2.7 years) in the elderly group. The recordings were conducted during an elbow flexion at both 20% and 40% maximum voluntary contraction. The signal amplitude was evaluated using root means square amplitude (RMSA) and the PDF shape of each HD-sEMG signal was assessed through skewness, excess Kurtosis, and robust functional statistics. These shape distance metrics evaluate the departure from Gaussianity related to muscle aging. a) We conducted a comparison study of the HD-sEMG PDF shapes between younger and elderly individuals. b) Evaluating differences between men and women. c) Considering monopolar and Laplacian electrode configurations that are sensitive to different muscle regions. ResultsA) The HD-sEMG PDFs of elderly subjects demonstrated a lower departure from Gaussianity than their younger counterparts. B) Women exhibited lower RMSA values than men, and, on average, a lower departure from Gaussianity whatever the age and contraction level C) Trends of departure from Gaussianity with contraction level, seems to be influenced by the electrode configuration. In fact, a decrease in Gaussianity departure is observed with monopolar recordings where an increase is observed with Laplacian one, clearly indicating different muscle region assessment. DiscussionThe findings highlight the influence of factors such aging, sex, contraction level and electrode montage on the shape of the HD-sEMG PDF, emphasizing the significance of using this descriptor for monitoring and better assessment of muscle aging.

Endovascular stimulation of the pudendal nerve using a stent-mounted electrode array

Objective. Previous preclinical and clinical studies have demonstrated that pudendal nerve is a promising target for restoring bladder control. The spatial proximity between the pudendal nerve and its accompanying blood vessels in the pudendal canal provides an opportunity for endovascular neurostimulation, which is a less invasive approach compared to conventional chronically implanted electrodes. In this study, we investigated the feasibility of excitatory stimulation and kilohertz-frequency block of the compound pudendal nerve in sheep using a stent-mounted electrode array.Approach. In a set of acute animal experiments, a commercially available hexapolar electrode catheter was introduced in the unilateral internal pudendal artery to deliver bipolar electrical stimulation of the adjacent compound pudendal nerve. The catheter electrode was replaced with a custom-made stent-mounted electrode array and the stimulation sessions were repeated. Global electromyogram activity of the pelvic floor and related sphincter muscles was recorded with a monopolar electrode placed within the urethra concurrently.Main results. We demonstrated the feasibility of endovascular stimulation of the pudendal nerve with both electrode types. The threshold current of endovascular stimulation was influenced by electrode-nerve distance and electrode orientation. Increasing the axial inter-electrode distance significantly decreased threshold current. Endovascular kilohertz-frequency nerve block was possible with the electrode catheter.Significance. The present study demonstrated that endovascular stimulation of the pudendal nerve with the stent-mounted electrode array may be a promising less invasive alternative to conventional implantable electrodes, which has important clinical implications in the treatment of urinary incontinence. Endovascular blocking of pudendal nerve may provide an alternative solution to the bladder-sphincter dyssynergia problem in bladder management for people with spinal cord injury.

Carbon Nanotubes as Controllable Electric-Field-Induced Bipolar Electrodes for Efficient Water Purification.

Advanced oxidation processes (AOPs) are the most efficient water cleaning technologies, but their applications face critical challenges in terms of mass/electron transfer limitations and catalyst loss/deactivation. Bipolar electrochemistry (BPE) is a wireless technique that is promising for energy and environmental applications. However, the synergy between AOPs and BPE has not been explored. In this study, by combining BPE with AOPs, we develop a general approach of using carbon nanotubes (CNTs) as electric-field-induced bipolar electrodes to control electron transfer for efficient water purification. This approach can be used for permanganate and peroxide activation, with superior performances in the degradation of refractory organic pollutants and excellent durability in recycling and scale-up experiments. Theoretical calculations, in situ measurements, and physical experiments showed that an electric field could substantially reduce the energy barrier of electron transfer over CNTs and induce them to produce bipolar electrodes via electrochemical polarization or to form monopolar electrodes through a single particle collision effect with feeding electrodes. This approach can continuously provide activated electrons from one pole of bipolar electrodes and simultaneously achieve "self-cleaning" of catalysts through CNT-mediated direct oxidation from another pole of bipolar electrodes. This study provides a fundamental scientific understanding of BPE, expands its scope in the environmental field, and offers a general methodology for water purification.

A Novel Technique for Intraoperative Mapping of the Somatosensory Cortex

Intraoperative mapping of the nervous system is used to identify "eloquent" cortical areas. In this technical report, we describe a novel way of mapping the somatosensory cortex so that injury to those critical pathways can be avoided. An 8-year-old female with drug resistant epilepsy presented for resection of a right posterior parietal focal cortical dysplasia. Left median nerve stimulation was used to record somatosensory evoked potentials (SEPs) directly from the somatosensory cortex with a strip electrode. A handheld monopolar electrode was also used to record both the median and tibial SEP. Total intravenous anesthesia with propofol and remifentanil was used. SEP recordings were obtained from a 4-contact strip electrode placed across the central sulcus. A phase reversal was identified and the most likely post central gyrus was noted. With the strip electrode left in place, a monopolar handheld electrode was used to record the median nerve SEPs from different locations on the postcentral gyrus. The tibial nerve was also stimulated to record where the highest amplitude tibial nerve SEP was present. This map was used delineate functionally "eloquent" areas to avoid during surgery. During resection, the median nerve SEP was recorded from the strip electrode continuously. No significant change in the SEP was noted, and the patient awoke without any sensory deficits. Sensory mapping of the cortex is possible with a handheld monopolar electrode. This technique is easy to perform and can help reduce neurological morbidity.

Role of the caudal Nucleus Tractus Solitarius and the Postinspiratory Complex in swallow production

The production of swallowing and its coordination with breathing is essential for homeostasis in most organisms. The postinspiratory complex (PiCo) is thought to regulate the transition between swallowing and breathing. Activation of PiCo triggers swallow production and stimulates laryngeal activation in a respiratory phase specific manner. However, little is known about PiCo’s role in swallow generation, which is thought to be controlled by the caudal portion of the Nucleus Tractus Solitarius (cNTS), presumably the swallow pattern generator (SPG). We hypothesize the cNTS is necessary for PiCo to trigger a swallow. Using both male and female Vglut2cre mice, a cre-dependent ChR2 AAV was bilaterally injected into PiCo and a cre-dependent inhibitory DREADD was bilaterally injected into the cNTS, specifically targeting the interstitial (SolI) and intermediate (SolIM) solitary nucleus. Twenty-one days after injection, using our freely breathing urethane anesthetized mouse model, swallows were stimulated by 1) injection of water into the oral cavity and 2) optogenetic stimulation of PiCo neurons; before and after DREADD activator, clozapine-N-oxide (CNO). Swallow and laryngeal activity were measured via monopolar suction electrodes of the hypoglossal (XII) and vagus (X) nerves as well as bipolar electromyogram (EMG) of the submental, laryngeal complex and costal diaphragm muscles. Post-hoc histological analysis was done to confirm areas of interest were targeted. We found that after activation of the inhibitory DREADD, located in the cNTS, swallow was not evoked by water stimulation nor optogenetic stimulation. We propose that PiCo relies on direct feedback from the cNTS in order to trigger swallow production. NIH F32 HL160102. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Full-Endoscopic Surgery for Hypothalamic Hamartoma Resection.

Hypothalamic hamartomas (HH) are rare developmental anomalies of the inferior hypothalamus that often cause refractory epilepsy, including gelastic seizures. Surgical resection is an effective method to treat drug-resistant epilepsy and endocrinopathy in a suitable patient group. Open surgery, endoscopic surgery, ablative procedures, and stereotactic radiosurgery can be utilized. In this study, we aimed to describe the full-endoscopic approach for HH resection. The technique involves the use of an intraoperative ultrasonography (USG) system, a 30° rigid endoscope system that has an outside diameter of 2.7 mm with two working channels, a stylet that has an outer diameter of 3.8 mm, a monopolar coagulation electrode, a fiberoptic light guide, and the endovision system. Microforceps and monopolar electrocautery are the two main surgical instruments for HH removal. The protocol is easy to apply after a particular learning curve has been passed and shorter than open surgical approaches. It leads to less blood loss. Full-endoscopic surgery for HH is a minimally invasive technique that can be applied safely and effectively with good seizure and endocrinological outcomes. It provides low surgical site pain and early mobilization.

Effect of the closed-loop hippocampal low-frequency stimulation on seizure severity, learning, and memory in pilocarpine epilepsy rat model.

In this study, the anticonvulsant action of closed-loop, low-frequency deep brain stimulation (DBS) was investigated. In addition, the changes in brain rhythms and functional connectivity of the hippocampus and prefrontal cortex were evaluated. Epilepsy was induced by pilocarpine in male Wistar rats. After the chronic phase, a tripolar electrode was implanted in the right ventral hippocampus and a monopolar electrode in medial prefrontal cortex (mPFC). Subjects' spontaneous seizure behaviors were observed in continuous video recording, while the local field potentials (LFPs) were recorded simultaneously. In addition, spatial memory was evaluated by the Barnes maze test. Applying hippocampal DBS, immediately after seizure detection in epileptic animals, reduced their seizure severity and duration, and improved their performance in Barnes maze test. DBS reduced the increment in power of delta, theta, and gamma waves in pre-ictal, ictal, and post-ictal periods. Meanwhile, DBS increased the post-ictal-to-pre-ictal ratio of theta band. DBS decreased delta and increased theta coherences, and also increased the post-ictal-to-pre-ictal ratio of coherence. In addition, DBS increased the hippocampal-mPFC coupling in pre-ictal period and decreased the coupling in the ictal and post-ictal periods. Applying closed-loop, low-frequency DBS at seizure onset reduced seizure severity and improved memory. In addition, the changes in power, coherence, and coupling of the LFP oscillations in the hippocampus and mPFC demonstrate low-frequency DBS efficacy as an antiepileptic treatment, returning LFPs to a seemingly non-seizure state in subjects that received DBS.

The Value of the Endoscope-Holding Arm in Transoral Pharyngeal Surgery.

Transoral pharyngeal surgery is mainly feasible with the use of a microscope or robotic systems. Data about alternative methods, with lower costs and easier availability, are sparse. We intended to examine to what extent the endoscope-holding arm is a suitable alternative to the microscope or robotic systems. We retrospectively reviewed subjects who underwent pharyngeal tumor resection with the endoscope-holding arm in our university department. We identified 13 subjects who underwent transoral pharyngeal surgery between November 2020 and November 2023. Most subjects presented with an oropharyngeal tumor (6/11 in the lateral wall or tonsil; 4/11 in the tongue base). The oropharyngeal lateral wall or tonsillar tumors were exposed with a standard mouth gag. The tongue-base tumors or hypopharyngeal tumors were exposed with an operating laryngoscope. Advantages over the microscope included an angled view. Advantages over robotic systems included haptic feedback and a faster setup. Advantages over both the microscope and robotic systems included lower costs and easier availability. Visualization with the endoscope was sufficient and similar to that of the microscope. Bimanual action was possible with surgical forceps and a monopolar electrode. Transoral pharyngeal surgery was feasible with the endoscope-holding arm. The endoscope-holding arm could be a cost-efficient alternative to the microscope or robotic systems.

Investigating Different Paradigms of Electrical Stimulation for Retinal Prosthesis

Background and Aims: Retinal prostheses have been suggested to restore vision for those with retinal diseases. This study aimed to identify the most effective stimulation approaches for retinal prostheses. Methods: This study examined various return electrode configurations on a realistic retinal ganglion cell model. Two return electrode configurations, monopolar and hexapolar, were implanted on epiretinal side. There were four waveforms used to send electrical current through the active electrode. The study also compared two stimulation methods: single stimulation and concurrent (parallel) stimulation. Results: Directly placing the retinal ganglion cell beneath the active electrode resulted in no significant difference in the required current for stimulating retinal ganglion cells between monopolar and hexapolar return electrodes, regardless of the stimulation waveform. For retinal ganglion cells located away from the active electrode, differences in the required current were noted between the two return electrode configurations. The study discovered that parallel stimulation with two or three active elec¬trodes lowered current requirements by up to 70% compared to single stimulation. Monophasic anod¬ic stimulation yielded the most effective pulse waveform, regardless of the configuration (monopolar or hexapolar) or stimulation mode (single or parallel). Moreover, monophasic cathodic stimulation usually targets retinal ganglion cells around the active electrode. Conclusions: These results illuminate the best stimulation strategies for enhancing the efficacy of retinal prosthe¬sis. The study highlights the importance of electrode arrangement, waveform selection, and single or concurrent stimulation for improving retinal ganglion cell activation.

Vagus Nerve Stimulation in the Carotid Triangle: An Effective Method for Monitoring the Recurrent Laryngeal Nerve in Thyroid and Parathyroid Surgery.

Our objective is the description of the technique of vagus nerve stimulation in carotid triangle in order to monitor the recurrent laryngeal nerve (RLN) during thyroid and parathyroid surgery. We stimulated the vagus nerve in the carotid triangle during 150 thyroid or parathyroid surgeries using a monopolar electromyography electrode inserted under the mastoid process towards the jugular foramen as a cathode, and using another subdermal electrode in the mastoid as an anode. Another complementary method of vagus stimulation was achieved with a pair of subdermal electrodes, placing the cathode at the mandibular angle and the anode at the mastoid. In all patients, compound muscle action potential (CMAP) was recorded in the vocal cords with both stimulation techniques, allowing semi-continuous monitoring to be carried out. Intraoperative lesions were detected in 16 of the cases; 9 of them were transient with CMAP recovery achieved when modifying surgical maneuvers. Vagus nerve stimulation in the carotid triangle is a reliable technique for monitoring the RLN in thyroid surgery. Vagus nerve stimulation in the carotid triangle is effective and safe for RLN monitoring, and it is a clear alternative to direct continuous stimulation of the nerve that by contrast requires its dissection in the carotid sheath.

Electrochemical Stimulation of Monopolar Electrodes

Changes in the electrostatic potential within an aqueous acidic solution induced by the passage of current between the Au disk of a stationary Au|Au ring disk electrode and a distant counter electrode, Idisk made it possible to stimulate the reduction of selenite to elemental selenium at the concentric Au ring electrode polarized at Eringo just positive to its otherwise expected onset. This effect was ascribed to variations in the surface overpotential, and, thus, in the rates of selenite reduction along the ring, we define, hereafter, as a monopolar electrode. The stimulation efficiency could be accurately determined from a coulometric analysis of the peak for Se oxidation observed by subsequently scanning the ring linearly toward positive potentials to yield selenite. Shown in the figure below is a series of linear scan \\voltammograms, LSV, recorded at a scan rate of 50 mV/s for the ring polarized at Eringo in the range 0.39 - 0.45 V (see legend) following Nstim = 40 between Edisk = 0.75 and 1.00 V, where the black curve corresponds to the LSV recorded without any prior stimulation under otherwise identical conditions. As clearly indicated the stripping charge associated with the oxidation of elemental Se increases as the potential at which the ring is polarized is decreased. Excellent quantitative agreement was obtained between the current flowing through the ring, Iring , and Eringo as a fucntion of Idisk and theoretical simulations employing COMSOL using parameters extracted from independent measurements performed under otherwise identical experimental conditions. This novel tactic is expected to open new prospects for gaining insight into surfacediffusion and other interfacial dynamics phenomena.AcknowledgementsThis work was supported by the US NSF Award 1808592Literature Cited1) Han, Q.; Georgescu, N. S.; Gibbons, J.; Scherson, D. Electrochim. Acta 2019, 325, 134957 Figure 1

Standard resting state electroencephalographic power density computed from posterior bipolar channel characterizes patients with Alzheimer’s disease

AbstractBackgroundAbnormalities in cortical sources of resting‐state eyes closed electroencephalographic (rsEEG) rhythms recorded by hospital settings (10‐20 montage) with 19 scalp electrodes characterized Alzheimer’s disease (AD) from preclinical to dementia stages. An intriguing rsEEG application is the monitoring and evaluating of AD progression in large populations with few electrodes in low‐cost devices. Here we assessed whether the above‐mentioned abnormalities could be observed from fewer scalp electrodes in patients with mild cognitive impairment (ADMCI) or dementia (ADD) due to AD.MethodClinical and rsEEG data acquired in hospital settings (10‐20 montage) from 88 ADD and 75 ADMCI participants and 70 age‐, education‐, and sex‐matched normal elderly controls (Nold) were available in an Italian‐Turkish archive (PDWAVES Consortium; www.pdwaves.eu). Standard spectral Fast Fourier Transform (FFT) analysis of rsEEG data for individual delta, theta, and alpha frequency bands was computed from 6 monopolar scalp electrodes to derive bipolar C3‐P3, C4‐P4, P3‐O1, and P4‐O2 markers.ResultThe ADMCI and ADD groups showed increased delta/alpha and theta/alpha power density at the C3‐P3, C4‐P4, P3‐O1, and P4‐O2 bipolar channels compared to the Nold group (Figure 1). The best classification accuracy (area under the receiver operating characteristic curve) between the ADD and ADMCI vs Nold individuals was reached using alpha2/theta power density computed at the C3‐P3 bipolar channel (AUROC for ADMCI vs Nold = 81%; AUROC for ADD vs Nold = 90%; Figure 2).ConclusionStandard rsEEG power density computed from six posterior bipolar channels characterized AD status from preclinical to dementia stages. These results may pave the way toward diffuse clinical applications in the health monitoring of dementia using low‐cost EEG systems with a strict number of electrodes in lower‐ and middle‐income countries.

Modeling Strategies Based on Multiple Neural Network Systems Applied for a Monopolar and Bipolar Electrocoagulation

The objective of this research was to evaluate the efficiency of an electrocoagulation system using iron and aluminum electrodes, arranged in both monopolar and bipolar arrangements, for the removal of acid red 18 dye. Experimental and modeling approaches were employed to investigate the system’s performance. The effects of operating parameters: including initial pH (3–9), current density (0.4–5.6 mA cm−2), charge passed (2.16–21.6 C cm−2), and initial dye concentration (50–300 mg l−1) were studied. The results demonstrated that an increase in electric current intensity and passed charge enhanced the removal of COD and dye. However, to minimize energy consumption, these parameters were optimized for different dye concentrations. The monopolar arrangement exhibited favorable performance for the both electrodes, primarily due to reduced ohmic drop effect, although the iron electrode generated sludge with better settling characteristics. The monopolar iron electrode consumed the least energy (38.3 kWh kg−1 COD). Experimental evaluation was conducted to assess the influence of key electrolysis process parameters on dye and COD removal. Additionally, neural network models, employing radial basis function and multilayer perceptron approaches, were utilized to predict system outputs based on initial characteristics (COD and dye) and operation conditions. The neural network models provided accurate predictions, offering practical insights for experimental applications.

Evaluation of the Use of Monopolar Low-Temperature Plasma Electrode in Lumbar Spinal Canal Expansion, Decompression, Bone Grafting, and Fusion Internal Fixation Surgery

Objective: This study aims to explore the therapeutic effects of using a monopolar low-temperature plasma electrode and a high-frequency electrotome during lumbar spinal canal expansion, decompression, bone grafting, and fusion internal fixation surgery. The study also investigates the impact of these techniques on inflammatory indicators and quality of life in patients. Methods: A total of 100 patients with lumbar spondylolisthesis treated between June (January) 2022 and July (March) 2023 were selected for this study. They were randomly divided into a control group and an observation group, with 50 cases in each group. Both groups underwent lumbar spinal canal expansion, decompression, bone grafting, and fusion internal fixation surgery. The control group used a high-frequency electrotome during surgery, while the observation group used a monopolar low-temperature plasma electrode. Surgical indicators (operation time, intraoperative blood loss), inflammatory indicators, pain levels, and quality of life were compared between the two groups. Results: The operation time in the observation group was shorter than that in the control group (P<0.05). Postoperative levels of TNF-α and CRP were lower in the observation group than in the control group (P<0.05). The observation group had lower VAS scores and higher SF-36 scores compared to the control group (P<0.05). Conclusion: The use of a monopolar low-temperature plasma electrode in lumbar spinal canal expansion, decompression, bone grafting, and fusion internal fixation surgery yields positive therapeutic outcomes. It effectively reduces operation time, alleviates patient's inflammatory responses and pain levels, aids in postoperative recovery, and enhances quality of life. These results suggest the potential for wider adoption.

Electrocoagulation technique and statistical analysis for treatment of real effluent from the pulp and paper industry

The electrochemical treatment of Organic Pollutants is a promising technique for substances with biodegradability resistance. In this research, the black liquor effluent originating from the Rakta Paper and Paper Company's mill, which employs rice straw as a raw material for paper fiber production, was subjected to treatment using the electrocoagulation method utilizing monopolar aluminum electrodes. The experiments were carried out using a 2.5 L electrochemical cell equipped with monopolar aluminum electrodes connected in parallel. The study examined the impact of operating parameters such as initial pH, current density, number of plates and electrolyte concentration on percentage removal and power consumption. The results revealed a positive correlation between the percentage of color removal and the duration of electrolysis, current density, sodium chloride concentration, and the number of electrodes used. The maximum color removal was observed at initial solution pH 6.5, experimental time 120 min, current density 61.8 A m−2, initial NaCl solution concentration 2 g L−1 and six aluminum plates. The statistical and mathematical data based on experimental results were analyzed using the central composite design from response surface methodology (RSM). The quadratic model is deemed appropriate owing to its substantial coefficient of determination (R2 = 0.99) and statistically significant p-value (≤ 0.0002), suggesting the model's significance. The experimental results indicate that the utilization of electrocoagulation as a treatment method for paper mill effluents has demonstrated superior efficacy compared to the adsorption technique.

Hazards Of Monopolar Diathermy Plate In Surgery.

Respected Madam, I would like to draw attention to the hazard of severe skin burns from the using the monopolar diathermy plate electrode during surgical procedures. Diathermy operates in two modes. The monopolar mode where the current enters the patient’s body through an active electrode and exits via a grounding pad attached to the patient.(1) During a recent total abdominal hysterectomy with bilateral salpingo-oophorectomy of a 30-year-old lady with a complex mass, the grounding pad for the electro-cautery had been applied to the left foot, which was found to have third degree burns after completion of the procedure. Similarly, an elderly diabetic lady presented to our outpatient department with the history of a 32 days old non-healing lesion on her left thigh and a Pfannenstiel incision on her abdomen. She had undergone a complete abdominal hysterectomy in another health care centre. During the surgery, the grounding pad was placed on her left thigh which suffered partial thickness burns. According to the patient’s history, the lesion was coin sized at the beginning, but due to poor glycemic control, it continued to involve the surrounding healthy tissue, including the bone. She had previously undergone multiple debridements for the lesion and was advised hip disarticulation after a thorough assessment by the senior management at our department. Even though the procedure was carried out, she, unfortunately, could not survive a few days following the disarticulation. The reason for the burns was a loose application of the grounding pad to the skin of the patient resulting in heat generation and sparking at the site preventing the current to pass safely causing skin burns. To prevent this, the grounding pad should be firmly applied to the skin preferably with crepe bandage. Some other ways to help prevent such complications are adhesive grounding pads and utilization of diathermy machines alarm system.(1)Surgical briefing with the entire perioperative team is necessary so that each individual understands their role in preventing electrosurgical hazards.(2) In addition to this, case reporting of surgical burns to the national database is necessary for implementation of such preventive measures.(3)

(Keynote) Electrode Stimulation: Ohmic Microscopy and the Monopolar Electrode

In a recent communication (1), we described a novel method of controlling the electrostatic potential in the solution neighboring a working electrode, we have dubbed the monopolar electrode , ME, polarized at a constant potential, EME, using a potentiostat. This tactic involved passing current between a second or stimulating electrode , SE, placed in front, and at a relatively small distance from the ME, and a distant auxiliary electrode, AE. Depending on the polarity of the current flowing through the SE, the electrostatic potential just outside the ME could be modified so as to increase or decrease the surface overpotential, and, thus modulate the rates of redox reactions at the ME|electrolyte interface. This presentation will review critical aspects of ohmic microscopy, and illustrate with two examples the electrode stimulation effect, using a ring disk electrode, RRDE, in which current flowing through the disk acting as the SE, is employed to induce reactions on the ring, acting as the ME, namely: i. the oxidation of adsorbed carbon monoxide on Pt using a Pt|glassy carbon RRDE and ii. the reduction of selenite to elemental Se on Au in aqueous 0.1 M HClO4 using a Au|Au RRDE. In both these cases, the stimulation current was generated by scanning the potential of SE within its double layer region, so as to minimize any changes in the actual composition of the solution adjacent to the ME, while monitoring the current flowing through the ME, IME . Under these conditions, the electrostatic potential in solution follows the primary current density. The efficiency of the stimulation process was determined by coulometric analysis of the CO oxidation current and in the case of selenite via a coulometric analysis of the current due to the oxidation of elemental Se produced by the reduction of selenite. The stimulation efficiency, in this latter case, could be accurately determined from a coulometric analysis of the peak for Se oxidation observed by subsequently scanning the ME linearly toward positive potentials to yield selenite. Excellent quantitative agreement was obtained between IME and EME as a function of Idisk and theoretical simulations employing COMSOL using parameters extracted from independent measurements performed under otherwise identical experimental conditions. This overall approach will open new prospects for gaining insight into the rates of surface diffusion and other interfacial dynamics phenomena.AcknowledgementsThis work was supported by a grant from NSF, CHE-1412060 References Han, Q.; Georgescu, N. S.; Gibbons, J.; Scherson, D. Acta 2019, 325, 134957.

The Effect of Partial Electrical Insulation of the Tip and Active Needle Length of Monopolar Irreversible Electroporation Electrodes on the Electric Field Line Pattern and Temperature Gradient to Improve Treatment Control.

Unintentional local temperature effects can occur during irreversible electroporation (IRE) treatment, especially near the electrodes, and most frequently near the tip. Partial electrical insulation of the IRE electrodes could possibly control these temperature effects. This study investigated and visualized the effect of partial electrical insulation applied to the IRE electrodes on the electric field line pattern and temperature gradient. Six designs of (partial) electrical insulation of the electrode tip and/or active needle length (ANL) of the original monopolar 19G IRE electrodes were investigated. A semolina in castor oil model was used to visualize the electric field line pattern in a high-voltage static electric field. An optical method to visualize a change in temperature gradient (color Schlieren) was used to image the temperature development in a polyacrylamide gel. Computational models were used to support the experimental findings. Around the electrode tip, the highest electric field line density and temperature gradient were present. The more insulation was applied to the electrodes, the higher the resistance. Tip and ANL insulation together reduced the active area of and around the electrodes, resulting in a visually enlarged area that showed a change in temperature gradient. Electrically insulating the electrode tip together with an adjustment in IRE parameter settings could potentially reduce the uncontrollable influence of the tip and may improve the predictability of the current pathway development.