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The propagation of electrical impulses along axons is highly accelerated by the myelin sheath and produces saltating or "jumping" action potentials across internodes, from one node of Ranvier to the next. The underlying electrical circuit, as well as the existence and role of submyelin conduction in saltatory conduction remain, however, elusive. Here, we made patch-clamp and high-speed voltage-calibrated optical recordings of potentials across the nodal and internodal axolemma of myelinated neocortical pyramidal axons combined with electron microscopy and experimentally constrained cable modeling. Our results reveal a nanoscale yet conductive periaxonal space, incompletely sealed at the paranodes, which separates the potentials across the low-capacitance myelin sheath and internodal axolemma. The emerging double-cable model reproduces the recorded evolution of voltage waveforms across nodes and internodes, including rapid nodal potentials traveling in advance of attenuated waves in the internodal axolemma, revealing a mechanism for saltation across time and space.
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Potenciales de Acción/fisiología , Vaina de Mielina/fisiología , Fibras Nerviosas Mielínicas/fisiología , Nódulos de Ranvier/fisiología , Animales , Axones/metabolismo , Axones/fisiología , Masculino , Modelos Neurológicos , Fibras Nerviosas Mielínicas/metabolismo , Técnicas de Placa-Clamp/métodos , Células Piramidales/fisiología , Ratas , Ratas WistarRESUMEN
During morphogenesis, large-scale changes of tissue primordia are coordinated across an embryo. In Drosophila, several tissue primordia and embryonic regions are bordered or encircled by supracellular actomyosin cables, junctional actomyosin enrichments networked between many neighbouring cells. We show that the single Drosophila Alp/Enigma-family protein Zasp52, which is most prominently found in Z-discs of muscles, is a component of many supracellular actomyosin structures during embryogenesis, including the ventral midline and the boundary of the salivary gland placode. We reveal that Zasp52 contains within its central coiled-coil region a type of actin-binding motif usually found in CapZbeta proteins, and this domain displays actin-binding activity. Using endogenously-tagged lines, we identify that Zasp52 interacts with junctional components, including APC2, Polychaetoid and Sidekick, and actomyosin regulators. Analysis of zasp52 mutant embryos reveals that the severity of the embryonic defects observed scales inversely with the amount of functional protein left. Large tissue deformations occur where actomyosin cables are found during embryogenesis, and in vivo and in silico analyses suggest a model whereby supracellular Zasp52-containing cables aid to insulate morphogenetic changes from one another.
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Actomiosina , Proteínas de Drosophila , Animales , Actomiosina/metabolismo , Actinas/metabolismo , Drosophila melanogaster/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Sarcómeros/metabolismo , Morfogénesis/genéticaRESUMEN
Wound healing through reepithelialization of gaps is of profound importance to the medical community. One critical mechanism identified by researchers for closing non-cell-adhesive gaps is the accumulation of actin cables around concave edges and the resulting purse-string constriction. However, the studies to date have not separated the gap-edge curvature effect from the gap size effect. Here, we fabricate micropatterned hydrogel substrates with long, straight, and wavy non-cell-adhesive stripes of different gap widths to investigate the stripe edge curvature and stripe width effects on the reepithelialization of Madin-Darby canine kidney (MDCK) cells. Our results show that MDCK cell reepithelization is closely regulated by the gap geometry and may occur through different pathways. In addition to purse-string contraction, we identify gap bridging either via cell protrusion or by lamellipodium extension as critical cellular and molecular mechanisms for wavy gap closure. Cell migration in the direction perpendicular to wound front, sufficiently small gap size to allow bridging, and sufficiently high negative curvature at cell bridges for actin cable constriction are necessary/sufficient conditions for gap closure. Our experiments demonstrate that straight stripes rarely induce cell migration perpendicular to wound front, but wavy stripes do; cell protrusion and lamellipodia extension can help establish bridges over gaps of about five times the cell size, but not significantly beyond. Such discoveries deepen our understanding of mechanobiology of cell responses to curvature and help guide development of biophysical strategies for tissue repair, plastic surgery, and better wound management.
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Actinas , Cicatrización de Heridas , Animales , Perros , Actinas/fisiología , Células de Riñón Canino Madin Darby , Movimiento Celular/fisiología , Cicatrización de Heridas/fisiologíaRESUMEN
Photoreceptors are electrically coupled to one another, and the spatiotemporal properties of electrical synapses in a two-dimensional retinal network are still not well studied, because of the limitation of the single electrode or pair recording techniques which do not allow simultaneously measuring responses of multiple photoreceptors at various locations in the retina. A multiple electrode recording system is needed. In this study, we investigate the network properties of the two-dimensional rod coupled array of the salamander retina (both sexes were used) by using the newly available multiple patch electrode system that allows simultaneous recordings from up to eight cells and to determine the electrical connectivity among multiple rods. We found direct evidence that voltage signal spread in the rod-rod coupling network in the absence of I h (mediated by HCN channels) is passive and follows the linear cable equation. Under physiological conditions, I h shapes the network signal by progressively shortening the response time-to-peak of distant rods, compensating the time loss of signal traveling from distant rods to bipolar cell somas and facilitating synchronization of rod output signals. Under voltage-clamp conditions, current flow within the coupled rods follows Ohm's law, supporting the idea that nonlinear behaviors of the rod network are dependent on membrane voltage. Rod-rod coupling is largely symmetrical in the 2D array, and voltage-clamp blocking the next neighboring rod largely suppresses rod signal spread into the second neighboring rod, suggesting that indirect coupling pathways play a minor role in rod-rod coupling.
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Células Fotorreceptoras , Retina , Animales , Células Fotorreceptoras/fisiología , Retina/fisiología , Urodelos/fisiologíaRESUMEN
Collective cell migration is seen in many developmental and pathological processes, such as morphogenesis, wound closure, and cancer metastasis. When a fish scale is detached and adhered to a substrate, epithelial keratocyte sheets crawl out from it, building a semicircular pattern. All the keratocytes at the leading edge of the sheet have a single lamellipodium, and are interconnected with each other via actomyosin cables. The leading edge of the sheet becomes gradually longer as it crawls out from the scale, regardless of the cell-to-cell connections. In this study, we found leading-edge elongation to be realized by the interruption of follower cells into the leading edge. The follower cell and the two adjacent leader cells are first connected by newly emerging actomyosin cables. Then, the contractile forces along the cables bring the follower cell forward to make it a leader cell. Finally, the original cables between the two leader cells are stretched to tear by the interruption and the lamellipodium extension from the new leader cell. This unique actomyosin-cable reconnection between a follower cell and adjacent leaders offers insights into the mechanisms of collective cell migration.
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Células Epiteliales , Animales , Movimiento CelularRESUMEN
BACKGROUND: Cable bacteria are filamentous members of the Desulfobulbaceae family that are capable of performing centimetrescale electron transport in marine and freshwater sediments. This longdistance electron transport is mediated by a network of parallel conductive fibres embedded in the cell envelope. This fibre network efficiently transports electrical currents along the entire length of the centimetrelong filament. Recent analyses show that these fibres consist of metalloproteins that harbour a novel nickelcontaining cofactor, which indicates that cable bacteria have evolved a unique form of biological electron transport. This nickeldependent conduction mechanism suggests that cable bacteria are strongly dependent on nickel as a biosynthetic resource. Here, we performed a comprehensive comparative genomic analysis of the genes linked to nickel homeostasis. We compared the genomeencoded adaptation to nickel of cable bacteria to related members of the Desulfobulbaceae family and other members of the Desulfobulbales order. RESULTS: Presently, four closed genomes are available for the monophyletic cable bacteria clade that consists of the genera Candidatus Electrothrix and Candidatus Electronema. To increase the phylogenomic coverage, we additionally generated two closed genomes of cable bacteria: Candidatus Electrothrix gigas strain HY106 and Candidatus Electrothrix antwerpensis strain GW34, which are the first closed genomes of their respective species. Nickel homeostasis genes were identified in a database of 38 cable bacteria genomes (including 6 closed genomes). Gene prevalence was compared to 19 genomes of related strains, residing within the Desulfobulbales order but outside of the cable bacteria clade, revealing several genomeencoded adaptations to nickel homeostasis in cable bacteria. Phylogenetic analysis indicates that nickel importers, nickelbinding enzymes and nickel chaperones of cable bacteria are affiliated to organisms outside the Desulfobulbaceae family, with several proteins showing affiliation to organisms outside of the Desulfobacterota phylum. Conspicuously, cable bacteria encode a unique periplasmic nickel export protein RcnA, which possesses a putative cytoplasmic histidinerich loop that has been largely expanded compared to RcnA homologs in other organisms. CONCLUSION: Cable bacteria genomes show a clear genetic adaptation for nickel utilization when compared to closely related genera. This fully aligns with the nickeldependent conduction mechanism that is uniquely found in cable bacteria.
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Genoma Bacteriano , Genómica , Homeostasis , Níquel , Filogenia , Níquel/metabolismo , Deltaproteobacteria/genética , Deltaproteobacteria/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismoRESUMEN
PURPOSE: There is currently a strong trend in developing RF coils that are high-density, lightweight, and highly flexible. In addition to the resonator structure of the RF coil itself, the balun or cable trap circuit serves as another essential element in the functionality and sensitivity of RF coils. This study explores the development and application of reproducible highly miniaturized baluns in RF coil design. METHODS: We introduce a novel approach to producing Bazooka baluns with printed coaxial capacitors, enabling the achievement of significant capacitance per unit length. Rigorous electromagnetic simulations and thorough hardware fabrication validate the efficacy of the proposed design across various magnetic field strengths, including 1.5 T, 3 T, and 7 T MRI systems. RESULTS: Bench testing reveals that the proposed balun can achieve an acceptable common-mode rejection ratio even when it is highly miniaturized. The use of printed capacitors allows for a notable reduction in balun length and ensures high reproducibility. Findings demonstrate that the proposed balun exhibits no RF field distortion even when placed close to the sample, making it suitable for flexible coils, wearable coils, and high-density coils, particularly in high-field MRI. CONCLUSION: The reproducibility inherent in the manufacturing process of printed coaxial capacitors allows for simple fabrication and ensures consistency in production. These advancements pave the way for the development of flexible coils, wearable coils, and high-density coils.
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Cable bacteria are filamentous bacteria that couple the oxidation of sulfide in sediments to the reduction of oxygen via long-distance electron transport over centimeter distances through periplasmic wires. However, the capability of cable bacteria to perform extracellular electron transfer to acceptors, such as electrodes, has remained elusive. In this study, we demonstrate that living cable bacteria actively move toward electrodes in different bioelectrochemical systems. Carbon felt and carbon fiber electrodes poised at +200 mV attracted live cable bacteria from the sediment. When the applied potential was switched off, cable bacteria retracted from the electrode. qPCR and scanning electron microscopy corroborated this finding and revealed cable bacteria in higher abundance present on the electrode surface compared with unpoised controls. These experiments raise new possibilities to study metabolism of cable bacteria and cultivate them in bioelectrochemical devices for bioelectronic applications, such as biosensing and bioremediation. IMPORTANCE: Extracellular electron transfer is a metabolic function associated with electroactive bacteria wherein electrons are exchanged with external electron acceptors or donors. This feature has enabled the development of several applications, such as biosensing, carbon capture, and energy recovery. Cable bacteria are a unique class of long, filamentous microbes that perform long-distance electron transport in freshwater and marine sediments. In this study, we demonstrate the attraction of cable bacteria toward carbon electrodes and demonstrate their potential electroactivity. This finding enables electronic control and monitoring of the metabolism of cable bacteria and may, in turn, aid in the development of bioelectronic applications.
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Bacterias , Fuentes de Energía Bioeléctrica , Electrodos , Electrodos/microbiología , Transporte de Electrón , Bacterias/metabolismo , Bacterias/genética , Fuentes de Energía Bioeléctrica/microbiología , Carbono/metabolismo , Sedimentos Geológicos/microbiología , Oxidación-Reducción , Técnicas ElectroquímicasRESUMEN
The vast majority of excitatory synaptic connections occur on dendritic spines. Due to their extremely small volume and spatial segregation from the dendrite, even moderate synaptic currents can significantly alter ionic concentrations. This results in chemical potential gradients between the dendrite and the spine head, leading to measurable electrical currents. In modeling electric signals in spines, different formalisms were previously used. While the cable equation is fundamental for understanding the electrical potential along dendrites, it only considers electrical currents as a result of gradients in electrical potential. The Poisson-Nernst-Planck (PNP) equations offer a more accurate description for spines by incorporating both electrical and chemical potential. However, solving PNP equations is computationally complex. In this work, diffusion currents are incorporated into the cable equation, leveraging an analogy between chemical and electrical potential. For simulating electric signals based on this extension of the cable equation, a straightforward numerical solver is introduced. The study demonstrates that this set of equations can be accurately solved using an explicit finite difference scheme. Through numerical simulations, this study unveils a previously unrecognized mechanism involving diffusion currents that amplify electric signals in spines. This discovery holds crucial implications for both numerical simulations and experimental studies focused on spine neck resistance and calcium signaling in dendritic spines.
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Espinas Dendríticas , Modelos Neurológicos , Señalización del Calcio , Dendritas , SinapsisRESUMEN
BACKGROUND AND AIMS: Many gastrointestinal (GI) disorders and precancerous conditions often present asymptomatically, leading to delayed patient diagnoses and treatment interventions. This study aimed to develop a novel cable-transmission magnetically controlled capsule endoscopy (CT-MCCE) system for detecting GI diseases and assess its safety and feasibility through clinical trials. METHODS: This prospective, multicenter, trial compared CT-MCCE with conventional gastroscopy in patients aged 18-75 years with upper GI diseases between October 2022 and May 2023. The primary endpoints included the evaluation of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in the detection of focal lesions within the esophagus, stomach, and duodenal bulb using CT-MCCE. RESULTS: A total of 180 individuals (mean age: 43.1 years, 52.22% female) were recruited from three hospitals in China. CT-MCCE detected lesions in esophagus with 97.22% sensitivity, 100% specificity, a PPV of 100%, a NPV of 98.18%, and 98.89% accuracy. CT-MCCE detected gastric focal lesions in the whole stomach with 96.81% sensitivity, 98.84% specificity, a PPV of 98.91%, a NPV of 96.59%, and 97.78% accuracy. CT-MCCE detected lesions in the duodenal bulb with 100% sensitivity, 100% specificity, a PPV of 100%, a NPV of 100%, and 100% accuracy. There were no significant differences between CT-MCCE and EGD regarding the cleanliness of the upper GI tract and visibility of the upper GI mucosa. However, CT-MCCE was associated with a lower incidence of discomfort than EGD (P<0.001). CONCLUSIONS: The diagnostic performance of CT-MCCE is comparable to that of EGD in the completion of upper GI tract examinations and lesion detection. Furthermore, the improved tolerance of CT-MCCE in detecting upper GI diseases was noted without any observed adverse events.
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BACKGROUND: His bundle pacing (HBP) engaged electrical activation of both ventricles by stimulating the His-Purkinje network, which could avoid marked ventricles dyssynchrony. The lead was given three to five clockwise rotations at the site with the His potential to anchor the interventricular septum. In 2018, the Multicenter His Bundle Pacing Collaborative Working Group recommended that the His bundle capture threshold should be lower than 2.5 V/1 ms in non-pacing-dependent patients, and pacing-dependent patients should have a lower adjacent ventricular capture threshold as self-backup. Therefore, to avoid safety issues such as loss of capture caused by increased threshold, we believe that more stringent criteria should be adopted in patients with atrioventricular block (AVB). In previous studies, the connection cable needed to be disconnected during the screwing. When the procedure was finished, the performer found that the patients with His bundle injury could obtain a lower threshold than those without His bundle injury. Although no studies of new bundle branch block (BBB) or AVB by the acute His bundle injury was reported. However, It is worrying that the damage of His bundle seems random during the procedure. How to balance avoiding severe injury with a lower capture threshold? At present, we report a case of light His injury and lower His capture threshold under continuous intracardiac electrocardiogram monitoring.
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Fascículo Atrioventricular , Estimulación Cardíaca Artificial , Electrocardiografía , Fascículo Atrioventricular/fisiopatología , Humanos , Estimulación Cardíaca Artificial/métodos , Masculino , Bloqueo Atrioventricular/terapia , Bloqueo Atrioventricular/fisiopatología , Anciano , Bloqueo de Rama/terapia , Bloqueo de Rama/fisiopatologíaRESUMEN
A 67-year-old male presented with symptomatic bradycardia caused by atrial fibrillation and underwent His bundle pacing (HBP) and left bundle branch pacing (LBBP). Electrocardiography (ECG) revealed a complete right bundle branch block (RBBB). John Jiang's connecting cable was used during the transventricular septal process. An interesting dynamic retrograde His bundle potential (RHP) was recorded with uninterrupted lead screws.
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BACKGROUND: Partial-thickness rotator cuff tears treated with an isolated bioinductive repair (IBR) in lieu of a completion-and-repair have shown complete healing. This treatment option is afforded by the remaining tendon's structural integrity, which is similar to that present in small/medium full-thickness tears (FTTs) when the rotator cable remains intact. This randomized controlled trial (RCT) investigated whether an IBR for small/medium full-thickness tears resulted in superior healing and patient-reported outcomes (PROs) compared with a sutured repair. METHODS: This prospective, double blinded (patients and outcome assessors), single-center randomized controlled trial enrolled patients ≥18 years with a small/medium (≤2.5 cm) full thickness supraspinatus tear and intact rotator cable. Patients were randomized and blinded to arthroscopic transosseous-equivalent repair (control, n = 30) or IBR (n = 30). The primary outcome was tendon quality on biopsy at 6 months. Secondary outcomes were PROs (American Shoulder and Elbow Surgeons [ASES], Constant-Murley Shoulder [CMS], and pain visual analogue scale scores) and tendon thickness and healing measured via MRI at 6, 12, and 24 months; satisfaction at 12 and 24 months; and time to return to work. RESULTS: Baseline demographic, tear, and surgical characteristics were comparable between the groups (IBR: mean age, 54.2 years, 14 male; control: mean age, 56.4 years, 16 male). Measured via a 6-month biopsy, highly organized, parallel bundles of collagen, without inflammation, were present in all IBR patients, whereas poorly organized, nonparallel collagen fibers were present in 24/30 (80%) of control patients (P < .0001), with 28/30 having minimal to mild inflammation. The increase in tendon thickness measured via MRI at 6 months from baseline was greater in the IBR group (2.0 mm) than in the control group (0.8 mm) (P < .0001). All IBR patients had 100% healing on MRI at 12 and 24 months. Compared with the control group, the IBR group had higher American Shoulder and Elbow Surgeons and Constant-Murley Shoulder scores at each evaluation, less pain at 6 and 12 months, and greater satisfaction at 12 and 24 months (P < .0003). The IBR group returned to work significantly faster (median 90 days [IQR, 25] vs. median 163.5 days [IQR, 24]; P < .0001) than the control group. CONCLUSION: Compared with a sutured repair, the IBR treatment resulted in superior tendon quality, patient outcomes, satisfaction, and return to work. The IBR enabled a robust healing response evident through MRI and biopsy evaluation, demonstrating superior tendon quality and healing.
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Artroscopía , Lesiones del Manguito de los Rotadores , Técnicas de Sutura , Humanos , Lesiones del Manguito de los Rotadores/cirugía , Método Doble Ciego , Masculino , Persona de Mediana Edad , Femenino , Artroscopía/métodos , Estudios Prospectivos , Anciano , Resultado del Tratamiento , Manguito de los Rotadores/cirugía , Medición de Resultados Informados por el Paciente , Cicatrización de Heridas , Imagen por Resonancia MagnéticaRESUMEN
BACKGROUND: Data on bacterial adhesion to cerclage cables are sparse. We aimed to compare 5 cerclage products for methicillin-resistant Staphylococcus aureus (MRSA) adhesion to determine the claim: Are nonmetallic polymer cables more resistant to bacterial adhesion than common metallic wires and cables? METHODS: The following 5 cerclage products were compared: (1) monofilament stainless steel (SS) wires; (2) multifilament SS cables; (3) multifilament cobalt chrome cables; (4) multifilament Vitallium alloy (cobalt-chrome-molybdenum [Co-Cr-Mo]) cables; and (5) multifilament nonmetallic polymer cables. Each was cut into 2 cm lengths and placed into 12-well plates. Of the wells, 5 were wire or cables in trypticase soy broth with MRSA, with the remaining wells being appropriate controls incubated for 24 hours at 37° C and 5% CO2 with shaking. Wires and cables were prepared and randomly imaged via scanning electron microscopy, with bacterial counts performed on 3 images of 3 different wires or cables per study group. The scanning electron microscopy technician and counting investigator were blinded. Additionally, SS wire and polymer cables were analyzed by microcalorimetry for metabolic activity and bacterial load. RESULTS: Bacterial attachment differed significantly between study groups in the middle section (P = .0003). Post hoc comparison showed no difference between groups individually (all P > .05) apart from polymer cables (median 551 bacteria) having significantly increased attached bacteria compared to the Vitallium alloy cable (157, P = .0004), SS cable (101, P = .0004), and SS wire (211, P = .0004). There was no difference between polymer and cobalt chrome cables (133, P = .056). Microcalorimetry supported these results, as polymer cables had a shorter time to max heat flow (6.2 versus 7.5 hours, P = .006), increased max heat flow (117 versus 64 uW, P = .045), and increased colony-forming units, indicating an increased bacterial load compared to SS wires. CONCLUSIONS: This in vitro study demonstrated that polymer cables have increased MRSA adhesion compared to common metallic wires and cables. Future studies are necessary to confirm the translation of increased bacterial adherence on polymer cables to increased rates of orthopaedic infections.
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Adhesión Bacteriana , Biopelículas , Hilos Ortopédicos , Staphylococcus aureus Resistente a Meticilina , Polímeros , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Biopelículas/efectos de los fármacos , Adhesión Bacteriana/efectos de los fármacos , Hilos Ortopédicos/microbiología , Humanos , Acero Inoxidable , Microscopía Electrónica de Rastreo , Ensayo de Materiales , Infecciones Estafilocócicas/prevención & control , Infecciones Estafilocócicas/microbiología , Aleaciones de CromoRESUMEN
Tendon-sheath structures are commonly utilized to drive surgical robots due to their compact size, flexibility, and straightforward controllability. However, long-distance cable tension estimation poses a significant challenge due to its frictional characteristics affected by complicated factors. This paper proposes a miniature tension sensor array for an endoscopic cable-driven parallel robot, aiming to integrate sensors into the distal end of long and flexible surgical instruments to sense cable tension and alleviate friction between the tendon and sheath. The sensor array, mounted at the distal end of the robot, boasts the advantages of a small size (16 mm outer diameter) and reduced frictional impact. A force compensation strategy was presented and verified on a platform with a single cable and subsequently implemented on the robot. The robot demonstrated good performance in a series of palpation tests, exhibiting a 0.173 N average error in force estimation and a 0.213 N root-mean-square error. In blind tests, all ten participants were able to differentiate between silicone pads with varying hardness through force feedback provided by a haptic device.
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Procedimientos Quirúrgicos Robotizados , Humanos , Procedimientos Quirúrgicos Robotizados/instrumentación , Diseño de Equipo , Robótica/instrumentaciónRESUMEN
Based on the need for real-time sag monitoring of Overhead Power Lines (OPL) for electricity transmission, this article presents the implementation of a hardware and software system for online monitoring of OPL cables. The mathematical model based on differential equations and the methods of algorithmic calculation of OPL cable sag are presented. Considering that, based on the mathematical model presented, the calculation of cable sag can be done in different ways depending on the sensors used, and the presented application uses a variety of sensors. Therefore, a direct calculation is made using one of the different methods. Subsequently, the verification relations are highlighted directly, and in return, the calculation by the alternative method, which uses another group of sensors, generates both a verification of the calculation and the functionality of the sensors, thus obtaining a defect observer of the sensors. The hardware architecture of the OPL cable online monitoring application is presented, together with the main characteristics of the sensors and communication equipment used. The configurations required to transmit data using the ModBUS and ZigBee protocols are also presented. The main software modules of the OPL cable condition monitoring application are described, which ensure the monitoring of the main parameters of the power line and the visualisation of the results both on the electricity provider's intranet using a web server and MySQL database, and on the Internet using an Internet of Things (IoT) server. This categorisation of the data visualisation mode is done in such a way as to ensure a high level of cyber security. Also, the global accuracy of the entire OPL cable sag calculus system is estimated at 0.1%. Starting from the mathematical model of the OPL cable sag calculation, it goes through the stages of creating such a monitoring system, from the numerical simulations carried out using Matlab to the real-time implementation of this monitoring application using Laboratory Virtual Instrument Engineering Workbench (LabVIEW).
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According to current regulations, welding is strictly prohibited for prestressed and tension cables. In response, this article proposes the use of a portable spot-welding machine to spot weld steel strands. This method generates a small current during spot welding, with a voltage of only 3 V to 5 V, and does not damage the internal structure of the steel strand. To effectively monitor cable tension in cable-supported structures, a novel approach utilizing a chip-based, encapsulated spot-welded strain sensor was investigated. The strain sensing capability, temperature sensitivity, stress relaxation, and static load responses were investigated on the proposed smart steel strand cables with spot-welded strain sensors. The theoretical analyses and finite element simulations revealed that the strain transfer efficiency of the spot-welded strain sensor exceeded 96%. The experimental results demonstrated that the load-strain relationship of the smart steel strand cable had a fitting degree greater than 0.999, and the tension errors obtained under different loads were within 1.26%. The tension full capacity errors measured at different temperatures were generally within 1.0%. The relaxation rate of the smart steel strand cable after 120 h was 3.78% and reduced the sensor accuracy error by 3.97%. Thus, the proposed strain sensor equipped with a smart steel strand cable is suitable for use in long-term tension monitoring.
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A Cable-Driven Continuum Robot (CDCR) that consists of a set of identical Cable-Driven Continuum Joint Modules (CDCJMs) is proposed in this paper. The CDCJMs merely produce 2-DOF bending motions by controlling driving cable lengths. In each CDCJM, a pattern-based flexible backbone is employed as a passive compliant joint to generate 2-DOF bending deflections, which can be characterized by two joint variables, i.e., the bending direction angle and the bending angle. However, as the bending deflection is determined by not only the lengths of the driving cables but also the gravity and payload, it will be inaccurate to compute the two joint variables with its kinematic model. In this work, two stretchable capacitive sensors are employed to measure the bending shape of the flexible backbone so as to accurately determine the two joint variables. Compared with FBG-based and vision-based shape-sensing methods, the proposed method with stretchable capacitive sensors has the advantages of high sensitivity to the bending deflection of the backbone, ease of implementation, and cost effectiveness. The initial location of a stretchable sensor is generally defined by its two endpoint positions on the surface of the backbone without bending. A generic shape-sensing model, i.e., the relationship between the sensor reading and the two joint variables, is formulated based on the 2-DOF bending deflection of the backbone. To further improve the accuracy of the shape-sensing model, a calibration method is proposed to compensate for the location errors of stretchable sensors. Based on the calibrated shape-sensing model, a sliding-mode-based closed-loop control method is implemented for the CDCR. In order to verify the effectiveness of the proposed closed-loop control method, the trajectory tracking accuracy experiments of the CDCR are conducted based on a circle trajectory, in which the radius of the circle is 55mm. The average tracking errors of the CDCR measured by the Qualisys motion capture system under the open-loop and the closed-loop control are 49.23 and 8.40mm, respectively, which is reduced by 82.94%.
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Partial discharge detection is considered a crucial technique for evaluating insulation performance and identifying defect types in cable terminals of high-speed electric multiple units (EMUs). In this study, terminal samples exhibiting four typical defects were prepared from high-speed EMUs. A cable discharge testing system, utilizing high-frequency current sensing, was developed to collect discharge signals, and datasets corresponding to these defects were established. This study proposes the use of the convolutional neural network (CNN) for the classification of discharge signals associated with specific defects, comparing this method with two existing neural network (NN)-based classification models that employ the back-propagation NN and the radial basis function NN, respectively. The comparative results demonstrate that the CNN-based model excels in accurately identifying signals from various defect types in the cable terminals of high-speed EMUs, surpassing the two existing NN-based classification models.
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There is a consensus within the scientific community regarding the effects on the environment, health, and climate of the use of renewable energy sources, which is characterized by a rate of harmful polluting emissions that is significantly lower than that typical of fossil fuels. On the other hand, this transition towards the use of more sustainable energy sources will also be characterized by an increasingly widespread electrification rate. In this work, we want to discuss whether electricity distribution and transmission networks and their main components are characterized by emissions that are potentially harmful to the environment and human health during their operational life. We will see that the scientific literature on this issue is rather limited, at least until now. However, conditions are reported in which the network directly causes or at least promotes the emissions of polluting substances into the environment. For the most part, the emissions recorded, rather than their environmental or human health impacts, are studied as part of the implementation of techniques for the early determination of faults in the network. It is probable that with the increasing electrification of energy consumption, the problem reported here will become increasingly relevant.