Bipolar Configuration Research Articles

Volumetric lesion analysis and validation of various bipolar configurations in radiofrequency ablation of ventricular myocardium in a bovine model.

The bipolar radiofrequency ablation(B-RFA) strategy was increasingly used to target deep intramural re-entrant foci responsible for the arrhythmia not ablated by conventional unipolar RFA / sequential unipolar RFA. Lesional characteristics of various bipolar configurations were largely unknown. To investigate the lesional geometry in relation to various factors to determine the most effective ablation strategy that minimises steam pops and achieves transmurality. To assess the temperatures at the return electrode. A custom-made validated ex-vivo bipolar ablation model was used to assess lesion formation. The myocardial sample was placed between two ablation catheters in four different orientations. Lesions were created using different power (30W, 40W, 50W) and time settings(30, 40 and 50s) with different catheter orientations. Data was analysed using binary logistic regression and multiple linear regression. Among 107 lesions, The volume of the active catheter lesion (266 +/- 137mm^3) significantly differed from their return electrode counterparts (130 +/- 91.8mm^3) (p < 0.001), and the temperatures at the return electrode end were lower than at the active electrode (p = 0.004). Higher power and longer duration application led to more frequent steam pops (p < 0.001), while true parallel configuration resulted in fewer steam pops (p < 0.001). A custom model without ground electrode temperature monitoring is safe and cost-effective. The safest strategy is a true parallel configuration with an inter-electrode distance of at least 15mm and a power of 30W to 40W, which generates lower steam pops and better transmurality.

Efficient removal of COD, BOD, oil & grease, and turbidity from oil-field produced water via electrocoagulation treatment.

The simple design, compactness, simultaneous treatment of multiple contaminants, absence of chemical usage, minimal sludge formation (reducing secondary pollution), low maintenance cost, and versatility to operate in both batch and continuous modes make electrocoagulation (EC) a promising choice for treating various types of industrial wastewater. In this study, EC was employed in batch mode to treat produced water obtained from an oil drilling site, to reuse it for injection purposes in the reservoir. Produced water typically contains high levels of total dissolved solids (TDS), turbidity, chemical oxygen demand (COD), biological oxygen demand (BOD), and oil & grease (O&G) contaminants. High-performing aluminum (Al) electrodes were chosen due to their stability, conductivity, and, most significantly, their high capacity for generating aluminum hydroxide ([Al(OH)₃]ₙ) flocs, which serve as carriers for contaminant capture. This compound has demonstrated remarkable effectiveness in trapping the aforementioned contaminants from produced water under various operating conditions, including the number of electrodes, supplied current, and electrode configuration (bipolar and monopolar). The impact of several factors, including the number of electrodes (varying from 4 to 8), current density (varying as 16, 79, 158 A/m2), and electrode configuration (bipolar and monopolar), was studied at room temperature and 250rpm agitation speed. Initial turbidity, COD, BOD, and O&G concentrations were measured at 38 NTU, 700.7ppm, 120ppm, and 32.8ppm, respectively. The EC treatment exhibited removal efficiencies of 51% for TDS, 85% for turbidity, 78% for COD, 80% for BOD, and 85% for O&G using a monopolar configuration with 8 electrodes, and 59% for TDS, 90% for turbidity, 85% for COD, 84% for BOD, and 86% for O&G using a bipolar configuration with eight electrodes. Additionally, cost estimation, considering electrode dissolution rate and power requirements, was conducted for the operation of both configurations.

Six transition patterns and seven capture types in different left bundle branch bipolar pacing configurations.

This study aims to explore the different transition patterns and capture types during two bipolar pacing tests based on the selective left bundle branch (LBB) capture determined by the continuous pacing and recording technique. In total, 67 patients completed two unipolar and two bipolar pacing tests based on selective LBB capture during screwing-in for left bundle branch pacing (LBBP) using the continuous pacing and recording technique. The electrophysiological characteristics and potential mechanisms of different pacing configurations were further evaluated in this study. We found six transition patterns and derived seven capture types in two bipolar pacing tests according to the analysis of continuous electrocardiogram and electrogram changes. Compared with the conventional configuration of "Tip-Ring+" bipolar pacing, "Ring-Tip+" testing had a lower threshold for simultaneous capture of the LBB and the left and right ventricular septum myocardium (1.57 vs. 2.84 V at 0.5 ms) and was the only configuration to yield the peculiar "LBBP + right ventricular septum pacing (RVSP)" capture type. In this study, we observed for the first time that "Ring-Tip+" bipolar pacing allows for a lower clinically applicable pacing threshold for simultaneous capture of the LBB and left and right ventricular septum myocardium, and the peculiar "LBBP + RVSP" capture type. This may be a more advantageous physiological pacing configuration, warranting further investigation and application in the future. Based on the specific selective LBB capture, we first found six transition patterns and derived seven capture types in two bipolar pacing tests due to the different thresholds of the LBB, left ventricular septal myocardial, and right ventricular septal myocardial. Compared with the conventional configuration of "Tip-Ring+" bipolar pacing, "Ring-Tip+" testing had a lower threshold for simultaneous capture of the LBB and the left and right ventricular septum myocardium (1.57 vs. 2.84 V at 0.5 ms) and was the only configuration to yield the peculiar "LBBP + RVSP" capture type. More pacing strategies should be released and investigated to achieve the best physiological pacing according to the individualized electrophysiological characteristics of patients.

An integrated probabilistic bipolar fermatean hesitant fuzzy transportation configuration for sustainable management of floral waste with risk assessment

This paper proposes the probabilistic bipolar fermatean hesitant fuzzy set (PBFHFS) and its triangular version as generalizations of bipolar fuzzy set (BFS) for delineating randomness and imprecision in a single framework. To enhance pragmatic applicability, the devised set has been examined based on its fundamental operations, basic properties, and defuzzification mechanism. Offerings made to temples are considered sacred, so they cannot be disposed of in landfills. Waste from temples is usually disposed of in nearby lakes, ponds, and rivers. Thus, management of the temple floral waste (TFW) is essential to enhance the sustainability of the environment. In this regard, a green 4-dimensional transportation system under PBFHF settings is developed for the effective and sustainable managements of floral waste that is dumped from places of worship. For the most cost-effective and environmentally friendly results, this transportation system optimises a number of metrics, transportation expenditure (TE), carbon emission (CE), transportation time (TT), and labour cost (LC). Three sub-models are further developed from the proposed model under PBFHF conditions by incorporating the theory of carbon policy and risk assessments. The suggested transportation system is addressed by employing a fuzzy methodology, fuzzy programming (FP) as well as two non-fuzzy approaches, weighted sum technique (WST) and goal programming technique (GP). At last, there is a numerical computation along with comparison analysis, management insights, a conclusion with limitations, and a scope for further study.

Dspace implementation of real-time selective harmonics elimination technique using modified carrier on three phase inverter

Introduction. In the contemporary world, alternative electrical energy has become an integral part of our daily existence, with the majority of our electrical materials, electronic devices, and industrial equipment relying on this energy source. Consequently, ensuring the quality of the electrical signal obtained is of paramount importance in the process of converting and distributing electrical energy. The improvement of the output voltage inverter can be achieved through adjustments to the inverter structure or by refining the control strategy. The novelty of the presented research lies in an innovative approach that employs real-time modulation for efficient control over the reduction of harmonics, alongside managing the fundamental component. This approach is applicable to both bipolar and unipolar configurations, featuring quarter-wave and half-wave symmetries. Purpose. Employing this modulation strategy aims to enhance the durability of the switching components and enhance the voltage output of the inverter. Methods. The methodology is founded on a sine-sine modulation as its foundational model. It constitutes an inventive pulse width modulation technique in which a reference sinusoidal waveform, operating at the desired signal frequency, is compared to a modified carrier signal with an identical time period as the reference signal. Results. This paper introduces a broader and more comprehensive approach, alongside specific solutions, for the control and mitigation of harmonics in three phase voltage source inverters. The proposed method offers precise control over the reduction of harmonics and the fundamental component, and it can be implemented in extensive power electronic converters. Practical value. To assess the effectiveness of the given control approach, we conducted simulations as well as real-time implementation employing Dspace DS1104 controller board. The outcomes were highly favorable, confirming the effectiveness and validity of the suggested control algorithm. References 15, tables 4, figures 7.

Bilateral centromedian nucleus of thalamus responsive neurostimulation for pediatric-onset drug-resistant epilepsy.

Neuromodulation therapies offer an efficacious treatment alternative for patients with drug-resistant epilepsy (DRE), particularly those unlikely to benefit from surgical resection. Here we present our retrospective single-center case series of patients with pediatric-onset DRE who underwent responsive neurostimulation (RNS) depth electrode implantation targeting the bilateral centromedian nucleus (CM) of the thalamus between October 2020 and October 2022. Sixteen patients were identified; seizure outcomes, programming parameters, and complications at follow-up were reviewed. The median age at implantation was 13 years (range 3.6-22). Six patients (38%) were younger than 12 years of age at the time of implantation. Ictal electroencephalography (EEG) patterns during patients' most disabling seizures were reliably detected. Ten patients (62%) achieved 50% or greater reduction in seizure frequency at a median 1.3 years (range 0.6-2.6) of follow-up. Eight patients (50%) experienced sensorimotor side effects, and three patients (19%) had superficial pocket infection, prompting the removal of the RNS device. Side effects of stimulation were experienced mostly in monopolar-cathodal configuration and alleviated with programming change to bipolar configuration or low-frequency stimulation. Closed-loop neurostimulation using RNS targeting bilateral CM is a feasible and useful therapy for patients with pediatric-onset DRE.

Power quality improvement of unipolar-input-bipolar-output DC transmission system via load power balancing

In DC transmission and distribution systems, both unipolar and bipolar transmission modes exist, and DC transformers used in these systems are also available in either unipolar or bipolar configurations. In actual systems, due to requirements such as economy, land occupation, and reliability, there is a tendency to use a system with unipolar input and bipolar output. However, the bipolar loads, if unbalanced, will lead to increased equipment costs and voltage imbalance, causing power quality problems. This paper defines the Power Unbalance Factor (PUF) to describe the power quality of the studied DC transmission system and presents an improved DC transformer topology based on a power balancing system. This topology realizes bipolar voltage balance and improves the power quality of the DC transmission system when the load is unbalanced. The influence of the proposed solution on the power design of the DC system is demonstrated through theoretical analysis, and its effectiveness for improving the DC power quality is verified by both simulations in MATLAB/Simulink environment and physical experiments. When the power electronic transformer needs to be overloaded, the proposed topology can reduce the design power of the two branches by using the difference power, which is economical.

Therapeutic DBS for OCD Suppresses the Default Mode Network.

Deep brain stimulation (DBS) of the anterior limb of the internal capsule (ALIC) is an emerging treatment for severe, refractory obsessive-compulsive disorder (OCD). The therapeutic effects of DBS are hypothesized to be mediated by direct modulation of a distributed cortico-striato-thalmo-cortical network underlying OCD symptoms. However, the exact underlying mechanism by which DBS exerts its therapeutic effects still remains unclear. In five participants receiving DBS for severe, refractory OCD (3 responders, 2 non-responders), we conducted a DBS On/Off cycling paradigm during the acquisition of functional MRI to determine the network effects of stimulation across a variety of bipolar configurations. We also performed tractography using diffusion-weighted imaging (DWI) to relate the functional impact of DBS to the underlying structural connectivity between active stimulation contacts and functional brain networks. We found that therapeutic DBS had a distributed effect, suppressing BOLD activity within regions such as the orbitofrontal cortex, dorsomedial prefrontal cortex, and subthalamic nuclei compared to non-therapeutic configurations. Many of the regions suppressed by therapeutic DBS were components of the default mode network (DMN). Moreover, the estimated stimulation field from the therapeutic configurations exhibited significant structural connectivity to core nodes of the DMN. Therapeutic DBS for OCD suppresses BOLD activity within a distributed set of regions within the DMN relative to non-therapeutic configurations. We propose that these effects may be mediated by interruption of communication through structural white matter connections surrounding the DBS active contacts.

Deep trapped bipolar heterocharges enable electret nanofibrous membranes for high-efficiency PM0.3 filtration

Recently frequent global pandemic outbreak triggers the demand of high-efficiency aerosol filtration materials. Most of traditional electret air filters can hardly achieve high efficiency (>99.99 %) due to limited charge density and inappropriate charge distribution. The influence mechanism of nanofibers bipolar heterocharge configuration on electrostatic capture of airborne particles is still confusing. Herein, a novel strategy to create high-efficiency air filters based on electret nanofibrous membranes with deep trapped heterocharge is reported. Space charges and dipole charges with opposite polarity are formed in electrospun membranes composed of different polymers under in-situ charge injection and electric poling during electrospinning. Nanoscale spatial surface potential mapping on individual nanofiber characterized by Kelvin probe force microscopy demonstrates bipolar heterocharge distribution. Numerical simulation shows that fiber heterocharge distribution endows the electret membrane with greater electrostatic field intensity gradient, resulting in stronger electrostatic force between nanofibers and airborne particles. With bipolar heterocharge configuration and bimodal fiber diameter distribution, the nanofibrous membranes exhibit high-efficiency low-resistance filtration property against 0.3 μm NaCl particles (99.994 %, 97.4 Pa) at 5.3 cm s−1. Furthermore, benefiting from charges with deep trap energy of 1.12 eV, the membranes still maintain 99.972 % filtration efficiency after 40 h exposure in 95 % relatively humidity. The prepared membranes brings new insight in the design of high-efficiency and long-term stability air filtration materials for public health precaution. This study not only reveals influence mechanism of nanofibers heterocharge distribution on electrostatic attraction, but also provides useful guidance for fiber charge configuration design to improve aerosol filtration performance of electret filters.

Refractory organic matter removal from mature leachate by bipolar electrocoagulation-electrooxidation reactor configurations

In this study, mature leachate treatment with combined electrochemical processes was investigated to benefit from the advantages of electrocoagulation (EC) and electrooxidation (EO) simultaneously. First, control experiments were conducted, the most effective anode-cathode combination for EO was selected as Ti/IrO2-Gr, the number of Al electrodes for EC was determined as 3 and the number of Fe electrodes was determined as 5. Optimization of process parameters of the combined system with Al and Fe electrodes was conducted with Box-Behnken design (BBD). With BBD, the effect of the process parameters (initial pH, current density, and reaction time) on the system responses (COD, UV254, and color removal efficiencies) was determined. The suitability of the created model in the study was analyzed statistically and the results of quadratic models were found compatible with experimental studies. The model's capacity for prediction was also confirmed by validation experiments under optimum conditions. By implementing the optimum conditions, COD, UV254, and color removal efficiencies were determined as 71.5 %, 60.2 %, and 93.2 %, respectively for the combined process with Al electrodes and 79.5 %, 68.0 %, and 97.7 %, respectively for the combined process with Fe electrodes. Correlation of actual and predicted data showed that BBD is reliable for optimizing process parameters of combined processes with Al and Fe electrodes. The obtained results showed that combined processes are more effective than hybrid processes, based on both pollutant removal efficiencies and energy consumption.

Feasibility of endovascular stimulation of the femoral nerve using a stent-mounted electrode array

Objective. Electrical stimulation of peripheral nerves has long been a treatment option to restore impaired neural functions that cannot be restored by conventional pharmacological therapies. Endovascular neurostimulation with stent-mounted electrode arrays is a promising and less invasive alternative to traditional implanted electrodes, which typically require invasive implantation surgery. In this study, we investigated the feasibility of endovascular stimulation of the femoral nerve using a stent-mounted electrode array and compared its performance to that of a commercially available pacing catheter. Approach. In acute animal experiments, a pacing catheter was implanted unilaterally in the femoral artery to stimulate the femoral nerve in a bipolar configuration. Electromyogram of the quadriceps and electroneurogram of a distal branch of the femoral nerve were recorded. After retrieval of the pacing catheter, a bipolar stent-mounted electrode array was implanted in the same artery and the recording sessions were repeated. Main Results. Stimulation of the femoral nerve was feasible with the stent-electrode array. Although the threshold stimulus intensities required with the stent-mounted electrode array (at 100–500 µs increasing pulse width, 2.17 ± 0.87 mA–1.00 ± 0.11 mA) were more than two times higher than the pacing catheter electrodes (1.05 ± 0.48 mA–0.57 ± 0.28 mA), we demonstrated that, by reducing the stimulus pulse width to 100 µs, the threshold charge per phase and charge density can be reduced to 0.22 ± 0.09 µC and 24.62 ± 9.81 µC cm−2, which were below the tissue-damaging limit, as defined by the Shannon criteria. Significance. The present study is the first to report in vivo feasibility and efficiency of peripheral nerve stimulation using an endovascular stent-mounted electrode array.

Very early fractures of the stylet-driven Biotronik Solia lead used for left bundle branch area pacing

Abstract Introduction Left bundle branch area pacing (LBBAP) has become increasingly popular due to the relatively simple implantation procedure allowing for conduction system pacing (CSP). Initially, lumen-less leads have been used primarily for CSP. However, several authors have published encouraging results using conventional stylet-driven pacemaker (PM) leads as well and our centers have largely adopted this approach. Methods In our two tertiary referral centers, we assessed all patients, who underwent a LBBAP lead implantation using any lead. We observed several early lead fractures, exhibiting a unique failure mechanism, which we illustrate in this case-series. Results Between January 2022 and November 2023 343/393 patients (87.3%) were implanted with a Solia pacemaker lead, 46/393 (11.7%) received a SelectSecure 3830 lead, and 4/393 (1.0%) another stylet-driven lead. Three patients (0.8%) who initially were implanted with a Solia lead experienced very early intracardiac lead fractures within 1, 11 and 13 months after implantation despite good initial electrical performance values (Table shows initial values and values during the time of failure (bold)). The first case was a 54 year-old woman with permanent 3d degree AV block receiving an LBBAP lead after lead extraction. Four weeks later, she presented with presyncope and exit block at maximum output in uni- and bipolar configuration. The second case was a 72 year-old man with intermittent 3rd degree AV block in the context of an ischemic heart disease. He received a dual-chamber LBBAP PM. 13 months after the implantation, a bipolar impedance &amp;gt; 2’500Ω and exit block were noted. The third case was 65 year-old man suffering from sick sinus syndrome. He initially underwent a dual-chamber PM implantation in 2011 and due to ventricular sensing issues a transvenous lead extraction and implantation of a LBBAP lead in October 2022. During device follow-up after 11 months, a fractured LBBAP lead with bipolar impedance &amp;gt;2’500Ω and exit block during threshold testing was noticed. In all cases, X-rays and macroscopic analysis consistently showed a disintegration of the lead immediately distal to the ring electrode (Figure; site of fracture marked with an arrow). Most likely, this was caused by the repetitive shear stress at the hinge point of the lead where it is entering the septum. Conclusion No dedicated stylet-driven CSP lead is available to date. The implantation site and technique for LBBAP may exert higher mechanical stress on the distal part of the lead, making it more prone to fracture than in a conventional position. Currently, the use of conventional stylet-driven leads is still off-label and the performance of such leads should be monitored closely.TableFigure

Bending, electroadhesion and sensing performances of single compliant electrode dielectric elastomer actuator based on SEBS gel

Dielectric elastomer actuators (DEAs) have great potential for application in soft robotics due to their ability to undergo substantial deformations, rapid response times, and high energy density when subjected to external electrical stimuli. However, the application of DEAs in the field of soft grippers is limited by their restricted direct electro-bending capability, output force, self-sensing capacity, and pre-stretching requirement. In this study, we fabricated a single compliant electrode DEA (SCE-DEA) which was made by sandwiching a compliant electrode between two layers of poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS)/white mineral oil (WO) dielectric elastomer films. The SCE-SEBS/WO was demonstrated to have the capacities of bending, sensing, and electroadhesion (EA). The SCE-SEBS/WO can be used in various soft actuator modes, such as the unipolar EA actuator, soft gripper, and soft vibrator. The grabbing mechanism of SCE-SEBS/WO-based soft grippers with opposite bipolar configuration is caused by electric field induced bending of SEC-SEBS/WO and subsequent electrostatic attraction between both SEC-SEBS/WO. The SEC-SEBS/WO based soft grippers have rapid response detachment, and ability to grasp various types of objects. Three-layer stacked SCE-SEBS/WO-60 (with 60 wt% of WO) exhibited 531 mN cm−2 of EA stress on the paper at 3.0 kV applied voltage, and the soft gripper made by four SCE-SEBS/WO-60 can successfully grab wood blocks weighing 162.4 g at 5 kV applied voltage. The sensing capacity of SCE-SEBS/WO based soft gripper was based on the bending strain dependent resistance changes of the compliant electrode. Our results provide new insights into the fabrication of DEA based soft grippers.

Effective Management of Recurrent Trauma-Induced Neck Pain With Radiofrequency Neurotomy Using the Nimbus Electrosurgical Radiofrequency Multitined Expandable Electrode: A Case Report

BACKGROUND: Radiofrequency neurotomy (RFN) can be an effective treatment for patients with chronic neck pain and cervicogenic headaches resistant to conservative care. However, the degree and duration of pain relief after RFN is dependent upon the thoroughness of target nerve coagulation. CASE REPORT: This is a case of a 37-year-old patient with debilitating neck pain and headaches following a motor vehicle accident. Successful local anesthetic block of the third occipital nerve (TON) confirmed pain of C2-C3 facet joint origin. An initial RFN treatment of the TON, using standard 18G electrodes in bipolar mode, resulted in complete symptom amelioration for 8 months. Repeat RFN, using the same electrode configuration, was unsuccessful in alleviating the severe neck pain and headaches, and produced no demonstrable sensory loss in the distribution of the TON. RFN was then performed using the Nimbus® electrosurgical RF multitined expandable electrode, which provides a larger zone of coagulation in volume than standard RFN electrodes even when used in bipolar configuration. CONCLUSIONS: The Nimbus procedure resulted in successful coagulation of the TON with sensory loss in the TON distribution and reinstatement of palliative relief. KEY WORDS: Cervical pain, radiofrequency neurotomy, third occipital nerve, Nimbus, case report

Computational analysis of electrode structure and configuration for efficient and localized neural stimulation.

Neuromodulation technique using electric stimulation is widely applied in neural prosthesis, therapy, and neuroscience research. Various stimulation techniques have been developed to enhance stimulation efficiency and to precisely target the specific area of the brain which involves optimizing the geometry and the configuration of the electrode, stimulation pulse type and shapes, and electrode materials. Although the effects of electrode shape, size, and configuration on the performance of neural stimulation have individually been characterized, to date, there is no integrative investigation of how this factor affects neural stimulation. In this study, we computationally modeled the various types of electrodes with varying shapes, sizes, and configurations and simulated the electric field to calculate the activation function. The electrode geometry is then integratively assessed in terms of stimulation efficiency and stimulation focality. We found that stimulation efficiency is enhanced by making the electrode sharper and smaller. A center-to-vertex distance exceeding 100µm shows enhanced stimulation efficiency in the bipolar configuration. Additionally, the separation distance of less than 1mm between the reference and stimulation electrodes exhibits higher stimulation efficiency compared to the monopolar configuration. The region of neurons to be stimulated can also be modified. We found that sharper electrodes can locally activate the neuron. In most cases, except for the rectangular electrode shape with a center-to-vertex distance smaller than 100µm, the bipolar electrode configuration can locally stimulate neurons as opposed to the monopolar configuration. These findings shed light on the optimal selection of neural electrodes depending on the target applications.

Lattice layout and optimizer effect analysis for generating optimal transcranial electrical stimulation (tES) montages through the metaheuristic L1L1 method.

This study focuses on broadening the applicability of the metaheuristic L1-norm fitted and penalized (L1L1) optimization method in finding a current pattern for multichannel transcranial electrical stimulation (tES). The metaheuristic L1L1 optimization framework defines the tES montage via linear programming by maximizing or minimizing an objective function with respect to a pair of hyperparameters. In this study, we explore the computational performance and reliability of different optimization packages, algorithms, and search methods in combination with the L1L1 method. The solvers from Matlab R2020b, MOSEK 9.0, Gurobi Optimizer, CVX's SeDuMi 1.3.5, and SDPT3 4.0 were employed to produce feasible results through different linear programming techniques, including Interior-Point (IP), Primal-Simplex (PS), and Dual-Simplex (DS) methods. To solve the metaheuristic optimization task of L1L1, we implement an exhaustive and recursive search along with a well-known heuristic direct search as a reference algorithm. Based on our results, and the given optimization task, Gurobi's IP was, overall, the preferable choice among Interior-Point while MOSEK's PS and DS packages were in the case of Simplex methods. These methods provided substantial computational time efficiency for solving the L1L1 method regardless of the applied search method. While the best-performing solvers show that the L1L1 method is suitable for maximizing either focality and intensity, a few of these solvers could not find a bipolar configuration. Part of the discrepancies between these methods can be explained by a different sensitivity with respect to parameter variation or the resolution of the lattice provided.

Distinguishing reflex from non-reflex responses elicited by transcutaneous spinal stimulation targeting the lumbosacral cord in healthy individuals

Transcutaneous spinal stimulation (TSS) studies rely on the depolarization of afferent fibers to provide input to the spinal cord; however, this has not been routinely ascertained. Thus, we aimed to characterize the types of responses evoked by TSS and establish paired-pulse ratio cutoffs that distinguish posterior root reflexes, evoked by stimulation of afferent nerve fibers, from motor responses, evoked by stimulation of efferent nerve fibers. Twelve neurologically intact participants (six women) underwent unipolar TSS (cathode over T11-12 spinal processes, anode paraumbilically) while resting supine. In six participants, unipolar TSS was repeated 2–3 months later and also compared to a bipolar TSS configuration (cathode 2.5 cm below T11-12, anode 5 cm above cathode). EMG signals were recorded from 16 leg muscles. A paired-pulse paradigm was applied at interstimulus intervals (ISIs) of 25, 50, 100, 200, and 400 ms. Responses were categorized by three assessors into reflexes, motor responses, or their combination (mixed responses) based on the visual presence/absence of paired-pulse suppression across ISIs. The paired-pulse ratio that best discriminated between response types was derived for each ISI. These cutoffs were validated by repeating unipolar TSS 2–3 months later and with bipolar TSS. Unipolar TSS evoked only reflexes (90%) and mixed responses (10%), which were mainly recorded in the quadriceps muscles (25–42%). Paired-pulse ratios of 0.51 (25-ms ISI) and 0.47 (50-ms ISI) best distinguished reflexes from mixed responses (100% sensitivity, > 99.2% specificity). These cutoffs performed well in the repeated unipolar TSS session (100% sensitivity, > 89% specificity). Bipolar TSS exclusively elicited reflexes which were all correctly classified. These results can be utilized in future studies to ensure that the input to the spinal cord originates from the depolarization of large afferents. This knowledge can be applied to improve the design of future neurophysiological studies and increase the fidelity of neuromodulation interventions.

Multi-Modal Spectroscopic Assessment of Skin Hydration.

Human skin acts as a protective barrier, preserving bodily functions and regulating water loss. Disruption to the skin barrier can lead to skin conditions and diseases, emphasizing the need for skin hydration monitoring. The gold-standard sensing method for assessing skin hydration is the Corneometer, monitoring the skin's electrical properties. It relies on measuring capacitance and has the advantage of precisely detecting a wide range of hydration levels within the skin's superficial layer. However, measurement errors due to its front end requiring contact with the skin, combined with the bipolar configuration of the electrodes used and discrepancies due to variations in various interfering analytes, often result in significant inaccuracy and a need to perform measurements under controlled conditions. To overcome these issues, we explore the merits of a different approach to sensing electrical properties, namely, a tetrapolar bioimpedance sensing approach, with the merits of a novel optical sensing modality. Tetrapolar bioimpedance allows for the elimination of bipolar measurement errors, and optical spectroscopy allows for the identification of skin water absorption peaks at wavelengths of 970 nm and 1450 nm. Employing both electrical and optical sensing modalities through a multimodal approach enhances skin hydration measurement sensitivity and validity. This layered approach may be particularly beneficial for minimising errors, providing a more robust and comprehensive tool for skin hydration assessment. An ex vivo desorption experiment was carried out on fresh porcine skin, and an in vivo indicative case study was conducted utilising the developed optical and bioimpedance sensing devices. Expected outcomes were expressed from both techniques, with an increase in the output of the optical sensor voltage and a decrease in bioimpedance as skin hydration decreased. MLR models were employed, and the results presented strong correlations (R-squared = 0.996 and p-value = 6.45 × 10-21), with an enhanced outcome for hydration parameters when both modalities were combined as opposed to independently, highlighting the advantage of the multimodal sensing approach for skin hydration assessment.

INFLUENCE OF THE ARC WELDING RELATED ELECTROMAGNETIC FIELD ON PACEMAKERS

The patients with implanted pacemaker or cardioverter-defibrillator are exposed to a certain risk of affecting this device by surrounding electromagnetic field. There are many sources of potential risky electromagnetic fields, arc welding is definitely one of them. The aim of this article is to present research focused on analysis of the pacemaker function during welding. There were performed in-vitro measurements with 9 pacemakers during metal inert gas (MIG) and tungsten inert gas (TIG) method arc welding. The responses of pacemakers were monitored by communication via programmer. Based on these measurements there are proposed safe distances from the main parts of welding machines, and also conditions and instructions for arc welding by patients with pacemakers. To ensure patient safety, patients should maintain suggested safe distances, use direct current with minimal possible amplitude, and weld in short intervals. Additionally, their pacemakers should be set to bipolar configuration.

Effects of bipolar plate flow channel configuration on thermal-electric performance of direct ammonia solid oxide fuel cell: Part Ⅱ- Promoting in-cell ammonia endothermic decomposition via a novel parallel S-type channel arrangement

This study explores impact of novel parallel S-type flow channels on ammonia decomposition and thermal-electric performance of direct ammonia solid oxide fuel cells (DA-SOFC). Four channel arrangements were numerically studied using single cell models: conventional unbent channels (UC–SOFC) and proposed single S-type channels (SSC–SOFC), double S-type channels (DSC-SOFC), triple S-type channels (TSC-SOFC). Cells with parallel S-type channel configurations outperformed unbent channel. Particularly, TSC-SOFC demonstrated the highest electrical performance, followed by DSC-SOFC, SSC-SOFC, and UC-SOFC, with power density improvements of 33.6%, 28.9%, and 28.9%, respectively, compared to UC-SOFC. Further results show that S-type channels exhibit self-heating effects, namely heat released from electrochemical reactions in the rear supplies ammonia decomposition in the front part of channel, enhancing H2 concentration and electrochemical reactions. Quantitatively, back-heat supplied to primary ammonia decomposition region increases by 33.3% in TSC-SOFC compared to UC-SOFC. Moreover, higher velocities in S-type channels enhance species diffusion towards rib underside, finally reducing concentration polarization and, improving power density. Besides of electrical performance, recycling waste heat from exhaust gases also improve the temperature uniformity cell, potentially benefiting the stability and lifetime of cell.