Pulsed Field Research Articles

Feasibility and Clinical Efficacy of Focal Pulsed Field Ablation in Patients With Non-Pulmonary Vein Triggered Atrial Arrhythmia From the Superior Caval Vein.

In patients with atrial arrhythmias originating from the superior vena cava (SVC), the use of radiofrequency energy to isolate the SVC is associated with a significant risk of injury both to the phrenic nerve and the sinus node. Pulsed field ablation (PFA) may overcome the disadvantages of thermal energy and improve both ablation efficacy and safety. We report the feasibility, safety, and clinical efficacy of focal monopolar PFA in patients with the origin of their atrial arrhythmia in the SVC. Nine patients (7 men, age 66 ± 8 years) with SVC-induced paroxysmal AF (n = 3), persistent AF (n = 5), or frequent premature atrial beats (n = 1) underwent SVC isolation using focal monopolar PFA. Acute circumferential SVC isolation was achieved in all cases, using 22 Ampere (A) or 25 A in areas with or without phrenic capture, respectively. The safety profile was excellent: two patients had transient sinus arrest and two had transient phrenic nerve stunning. Sinus node and phrenic nerve function recovered during the procedure, and no permanent damage was observed at follow-up. Coronary vasospasm occurred (and quickly resolved after injection of nitroglycerin) in one patient during additional ablation of a focal atrial tachycardia at the coronary sinus ostium. Kidney function remained stable before and after ablation in all patients. In this patient cohort with SVC-triggered atrial arrhythmia, isolation using focal monopolar PFA was feasible, effective, and safe. No permanent injury to the phrenic nerve or sinus node was observed.

Mechanism Analysis of Bubble Discharge Within Silicone Gels Under Pulsed Electric Field

Silicone gel, used in the packaging of high-voltage, high-power semiconductor devices, generates bubbles during the packaging process, which accelerates the degradation of its insulation properties. This paper establishes a testing platform for electrical treeing in silicone gel under pulsed electric fields, investigating the effect of pulse voltage amplitude on bubble development and studying the initiation and growth of electrical treeing in a silicone gel with different pulse edge times. The relationship between bubbles and electrical treeing in silicone gel materials is discussed. A two-dimensional plasma simulation model for bubble discharge in silicone gel under pulsed electric fields is developed, analyzing the internal electric field distortion caused by the response times of different ions and electrons. Additionally, the discharge current and its effects on silicone gel under pulsed electric fields are examined. By studying the influence of different pulse edge times, repetition frequencies, and temperatures on discharge current magnitude and ozone generation rates, the impact of electrical breakdown and chemical corrosion on the degradation of organic silicone gel under various operating conditions is analyzed. This study explores the macroscopic and microscopic mechanisms of dielectric performance degradation in organic silicone gel under pulsed electric fields, providing a basis for research on high-performance packaging materials and the development of high-voltage, high-power semiconductor devices.

Experimental Study of Stress Reactions Induced by Low-Intensity Microwave Radiation

A study was made of the severity and dynamics of changes in indicators reflecting the state of the blood system (the number of myelokaryocytes in the femur, the level of CFU-S in the exo and endotest, hemolytic resistance of erythrocytes, as well as the mass and cellularity of the thymus) in mice exposed to monochromatic pulsed electromagnetic fields of the frequency range 2.27–2.78 GHz with an average power flux density of 60 μW/cm2 at doses from 0.086 to 0.86 J/g. It is shown that under repeated exposure to electromagnetic fields, the bioeffect cumulates, leading to the development of a stress-like adaptive reaction in animals.

Ultrafast optical induction of magnetic order at a quantum critical point

Time-resolved ultrafast spectroscopy has emerged as a promising tool to dynamically induce and manipulate non-trivial electronic states of matter out-of-equilibrium. Here we theoretically investigate light pulse driven dynamics in a Kondo lattice system close to quantum criticality. Based on a time-dependent auxiliary fermion mean-field calculation we show that light can dehybridize the local Kondo screening and induce oscillating magnetic order out of a previously paramagnetic state. Depending on the laser pulse field amplitude and frequency the Kondo singlet can be completely deconfined, inducing a dynamic Lifshitz transition that changes the Fermi surface topology. These phenomena can be identified in harmonic generation and time-resolved angle-resolved photoemission spectroscopy spectra. Our results shed new light on non-equilibrium states in heavy fermion systems.

The Performance of a New Nanosecond Pulsed Field Ablation Surgical Clamp in Ablation of Cardiac Tissue: A Chronic Porcine Model.

The purpose of this chronic porcine model is to demonstrate safety and efficacy of a new nanosecond pulsed field ablation (nsPFA) parallel clamp in ablating different cardiac tissue. The Pulse Biosciences nsPFA CellFX Clamp System was tested on 6 pigs. Ablations were performed in all four heart chambers by delivering a sequence of very short duration high amplitude electrical pulses taking 1.25 seconds per application independent of tissue thickness or type. Testing for electrical exit block was performed at the time of surgery and at study termination. At 35 days, animals were euthanized and anonymized histopathology was performed to assess lesion width, depth and transmurality. Lesion pattern and general safety was compared to 6 animals in which a bipolar radiofrequency clamp was used (AtriCure Synergy Isolator System). There were no device-related serious adverse events in the nsPFA group. There was one early device related mortality at day 24 in the RFA group from perforation of one of the ventricular ablation sites. There were also two intracardiac thrombotic events with one systemic thromboembolic event in the radiofrequency group. Exit block was confirmed in all animals from both groups for the pulmonary veins and the posterior wall. Histological findings were consistent and demonstrated mature scar formation in all nsPFA ablation specimens, while a 7.1% rate of incomplete histopathological scar maturation was present in the RFA group. In this chronic porcine model, a single 1.25 second application independent of tissue thickness with the CellFX Parallel Clamp System demonstrated promising safety and efficacy profile. All lesions produced by this technology resulted in persistent exit block around pulmonary veins and the posterior atrial wall consistent with a reliable, contiguous and transmural ablation without injury to adjacent organs.

Photobiostimulation Therapy (PBST) and Pulsed Electromagnetic Field Therapy (PEMF) in Hair Loss Treatment: Multicentric, Retrospective, Case-Control Study.

The combined use of micro-needling (MND), growth factors (GFs), and low-level light/laser therapy (LLLT), here identified as photobiostimulation therapy (PBST) and pulsed electromagnetic field therapy (PEMF), is a hair loss (HL) treatment that needs to be standardized as it seems to have promising effects on hair regrowth (HR-G). The study compared the clinical and instrumental results obtained in patients affected by androgenic alopecia (AGA) and HL related to COVID-19 treated using PEMF combined with PBST with those obtained by only PBST. A multicentric, retrospective, observational, case-control study was conducted. Fifty-three patients were initially enrolled (30 males classified as stages I-III vertex by the Norwood-Hamilton scale, while 23 females classified in stages I-II by the Ludwig scale). Forty patients (20 females and 20 males) were analyzed after exclusion and inclusion criteria assessment. Twenty patients were treated with the combined use of PEMF and PBST (study group - SG) while 20 patients were treated with PBST (control group -CG). The HR-G was evaluated through photography, physician's, and patient's global assessment scales, in addition to standardized phototrichograms, during a short follow-up at T0-baseline, T1-16 weeks. The promising results in SG patients, represented by a hair count (HC) increase of 14 hairs/0.65cm2 at T1 after 16 weeks in the targeted area, compared with the baseline results (41 ± 2 hairs/0.65cm2 at T1 versus 27 ± 2 hairs/0.65cm2 at baseline), were observed using computerized trichograms. There was a statistically significant difference in HR-G (p = 0.0325) compared with an HC increase of 11 ± 2 hairs/0.65cm2 in the CG. The comparison between SG and CG indicated that PEMF combined with PBST was a more efficient strategy in HR-G in terms of HC improvement than PBST alone. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The clinical effects of pulsed electromagnetic field therapy for the management of chronic ankle instability: a study protocol for a double-blind randomized controlled trial

BackgroundChronic ankle instability is associated with long-term neuromuscular deficits involving poor postural control and peroneal muscular impairment. Symptoms of chronic ankle instability hinder engagement in physical activity and undermine the patient’s quality of life. Despite the existence of various treatment modalities, none has conclusively provided evidence of clinical effectiveness in counteracting neuromuscular deficits, such as arthrogenic muscle inhibition of the peroneal longus (PL). Pulse electromagnetic field therapy employed as an adjunct biophysical therapy can potentially improve stability by mitigating peroneal muscle weakness and by activating the peroneal muscle. We postulate that by combining standard care (muscle strengthening, balance training, and range of motion exercise) with pulse electromagnetic field therapy, postural control stability and peroneal muscle weakness will significantly improve.MethodsThis is a prospective, randomized, double-blind, placebo-controlled trial. A total of 48 adults with chronic ankle instability will be recruited and randomly allocated into either the intervention or control groups. The intervention group (n = 24) will receive active pulse electromagnetic field therapy and standard exercise training, while the control group (n = 24) will receive sham pulse electromagnetic field therapy and standard exercise training for 8 weeks. Primary and secondary outcomes will be evaluated at baseline, week 4, 8 as well as at 3-, 6-, and 12-month follow-up visits.DiscussionChronic ankle instability is a common debilitating condition without a curative conservative treatment. Investigating different treatment modalities will be essential for improving rehabilitation outcomes in this clinical population. This study will investigate the effectiveness of pulsed electromagnetic field therapy on the functional and clinical outcomes in the chronic ankle instability population. This trial may demonstrate this non-invasive biophysical therapy to be an effective measure to help patients with CAI.Trial registrationClinicalTrials.gov NCT05500885. Registered on August 13, 2022.

Frequency conversion in a hydrogen-filled hollow-core fiber using continuous-wave fields

In large-area quantum networks based on optical fibers, photons are the fundamental carriers of information as so-called flying qubits. They may also serve as the interconnect between different components of a hybrid architecture, which might comprise atomic and solid-state platforms operating at visible or near-infrared wavelengths, as well as optical links in the telecom band. Quantum frequency conversion is the pathway to change the color of a single photon while preserving its quantum state. Currently, nonlinear crystals are utilized for this process. However, their performance is limited by their acceptance bandwidth, tunability, polarization sensitivity, and undesired background emission. A promising alternative is based on stimulated Raman scattering (SRS) in gases. Here, we demonstrate polarization-preserving frequency conversion in a hydrogen-filled antiresonant hollow-core fiber. This approach holds promises for seamless integration into optical fiber networks and interfaces to single emitters. Disparate from related experiments that employ a pulsed pump field, we here take advantage of two coherent continuous-wave pump fields.

Feasibility of pulsed field ablation for atrial fibrillation under mild conscious sedation

Abstract Background Pulsed field ablation (PFA) is a new modality for pulmonary vein isolation (PVI) for atrial fibrillation (AF). PFA is performed under general anaesthetic (GA) or deep sedation with propofol, but this requires anaesthetic support in many countries, restricting use. No study has tested the feasibility of PFA under mild conscious sedation (MCS). Methods We prospectively recruited patients undergoing PFA PVI, offered the option of MCS delivered by electrophysiologists, and compared these with patients who opted for GA. MCS comprised intravenous midazolam and fentanyl. All procedures were performed under anaesthetic supervision in case of requirement to convert to GA, which formed the primary outcome. Results Twenty-three patients were recruited (8 MCS, 15 GA). One patient (1/8 [12.5%]) required conversion from MCS to GA. Total procedural times were similar between groups (MCS 92 ± 12.4 min vs. GA 101 ± 17.3 min; p = 0.199). High mean sedative doses were required in the MCS group (5.12 ± 0.83 mg midazolam and 209 ± 40 mcg fentanyl). Median intraprocedural pain perception by the patient, rated from 0 to 100 was 45 (IQR 22.5–72.5) in the MCS group. Post-procedural groin pain (0 [0–0] vs. 5 [0–35]; p = 0.027) and throat pain (0 [0–0] vs. 10 [5–40]; p = 0.001) were lower in the MCS group. Conclusion PFA under MCS is feasible in selected patients but pain and tolerance may be suboptimal, and high sedative doses are required. Graphical abstract

Insights from pulse field energy in patients with prosthetic mechanical heart valves undergoing ablation for atrial fibrillation

Insights from pulse field energy in patients with prosthetic mechanical heart valves undergoing ablation for atrial fibrillation

Extraction of antioxidant and antibacterial agents from avocado (Persea americana) seed using Pulsed Electric Field method

The abundance of avocado seeds causes environmental problems. Therefore, avocado seeds, which are high in bioactive compounds, have been utilized. Several extraction methods have been explored to maximize this utilization. However, conventional extraction methods present major challenges due to disadvantages such as requiring high temperatures, high energy consumption, long extraction times, and producing solvent waste. To that purpose, the Pulse electric field (PEF) extraction method was developed, which is highly efficient, has a short extraction process, is environmentally friendly, and does not produce solvent waste. This study observed the effect of electric field strength (2.5–7.5 kV/cm) and pulse frequency (100–250 Hz) until an optimum point on the properties of avocado seed extract (Avs) as an antioxidant and antibacterial agent. The results show that increasing the electric field strength and pulse frequency boosts the extraction yield and total phenolic content (TPC). This is highly supported by SEM images, which show more pores, cavities, and disrupted membrane cells as the electric field strength and pulse frequency increased. GC-MS and FTIR analysis also showed that the extract contains bioactive compounds such as polyphenols, fatty acids, and other compounds with the representing peaks OH, C−H stretch, CC, −C−H stretch, C−O stretch, and in-plan deformation vibration CH indicating as antioxidant and antibacterial agents. The extract obtained at 7.5 kV/cm with a pulse frequency of 250 Hz shows the best performance of bioactive potential indicated by antioxidant activity, IC50, and surface area of the inhibition zone against E. coli and S. aureus, which are 95.56 %, 90 µg/mL, 396 mm2, and 785 mm2, respectively. The inhibitory zones of the two microbials were relatively stable until the seventh day of observation. This research showed that the EF extraction method serves as an eco-extraction technology of natural bioactive compounds, which has high potential application as an antioxidant and antibacterial agent.

Enhancement of extraction efficiency and functional properties of chickpea protein isolate using pulsed electric field combined with ultrasound treatment

Chickpea protein isolate (CPI) is a promising dietary protein with the advantages of low allergenicity, easy digestion and balanced composition of essential amino acids. However, due to the thick skin of chickpeas, the extraction of CPI is challenging, resulting in lower efficiency of the alkaline extraction-isoelectric precipitation (AE-IEP) method. Therefore, the present study investigated the effect of pulsed electric field combined with ultrasound (PEF-US) treatment on the extraction efficiency of CPI and the functional properties was characterized. Parameter optimization was carried out using response surface methodology (RSM), with the following optimized conditions: pulse duration of 87 s, electric field intensity of 0.9 kV/cm, ultrasonic time of 15 min, and ultrasonic power of 325 W. Under the optimized conditions, the yield of CPI after combined (PEF-US) treatment was 13.52 ± 0.13 %, which was a 47.28 % improvement over the AE-IEP method. This yield was better than that obtained with either individual PEF or US treatment. Additionally, the functional properties (solubility, emulsification, and foaming) of CPI were significantly enhanced compared to AE-IEP. However, the stability of emulsification and foaming did not show significant differences among the four methods. The PEF-US method efficiently extracts CPI with excellent functional properties, enabling the production of proteins as desired functional additives in the food industry.

Hyperbaric inactivation at 150–250 MPa of Alicyclobacillus acidoterrestris spores at room temperature and effect of innovative technologies pre-treatments

This study evaluated hyperbaric inactivation (HI) at 150, 200 and 250 MPa, up to 24 h (at ambient temperatures,18–23 °C) to inactivate Alicyclobacillus acidoterrestris (ACB) spores in apple juice. The effects of pre-treatments on spores by thermal pasteurization (90 °C, 30 s), high pressure processing (600 MPa, 3 min, HPP), pulsed electric field (30 kV, 80 μs, 1400 Hz, PEF), and ultrasound (67 W, 20 kHz, 5 min, US) prior to HI was evaluated. The results were fitted to non-linear inactivation kinetic models, including Biphasic, Log-logistic, and Weibull. Without a previous pre-treatment, ACB spores were reduced ≈4.56 log units by HI after 24 h, regardless of the pressure level (initial load around 6 log CFU/mL). The pre-treatments did not affect ACB spores during HI (≈4–5 log units' inactivation after 24 h under pressure), except for PEF that resulted in a lower inactivation (≈3.5 log units after 24 h under pressure). Phase contrast microscopy revealed that the spores were unable to form a vegetative cell during HI. HI at 5 °C resulted in a lower inactivation level, with 3.86, 2.54 and 1.77 log units of inactivation, respectively, at 150, 200 and 250 MPa after 96 h. Industrial relevanceThe results of this work point to the possibility of using HI, before or after conventional thermal pasteurization and other nonthermal technologies (HPP, PEF, and US) to process apple juice, to inactivate ACB spores at room temperature and also under refrigeration. This methodology should be further studied in the context of ACB spores' high thermal stability and its industrial relevance.

Pulsed Electric Field Pretreatment Enhances the Enzyme Hydrolysis of Baker’s Yeast

Baker’s yeast is a key starting material for producing extracts with diverse compositions and applications. This study investigates the effect of pulsed electric field (PEF) pretreatment, which induces irreversible electropermeabilization, on the enzymatic hydrolysis of yeast. Cell suspensions were exposed to monopolar rectangular pulses in a continuous flow system followed by 4 h of incubation with Alcalase at concentrations of 0.2% and 0.5%. PEF pretreatment significantly improved enzymatic hydrolysis, with maximum intracellular content recovery under electrical conditions resulting in outlet temperatures of 56–58 °C. The released protein reached 163.7 ± 13 mg per gram of dry cell weight (DCW). SDS-PAGE analysis showed that the extracts predominantly contained peptides with molecular masses below 4.7 kDa. The phenolic content was comparable to that of cell lysates obtained after mechanical disruption. The free α-amino nitrogen content and total antioxidant activity reached 218.2 ± 26 mg/gDCW and 53.4 ± 4.6 mg TE/gDCW, respectively, representing 3.2-fold and 2.65-fold increases compared to cell lysates. The hydrolysates from PEF-pretreated cells demonstrated a positive effect on the proliferation of the human keratinocyte cell line HaCat. The obtained data lead to the conclusion that PEF pretreatment is a promising approach to enhance the production of yeast hydrolysates with various applications.

Numerical simulation on metallurgical transport phenomena during DC casting of large-size Mg-Gd-Y alloy billet under various magnetic fields

The manufacture of large-size rare-earth Magnesium alloy billets by direct-chill (DC) casting process is now facing great technical challenges, mainly due to the high cost of casting experiments, and such casting defects like severe cracking, macrosegregation, and non-homogenized solidified structure. Based on the low-cost and high-efficiency numerical simulation method, the present study systematically explores the effects of single pulsed and alternating magnetic fields (PMF and AMF), differential-phase pulsed and alternating magnetic fields (DPMF and DAMF) on DC casting metallurgical transport phenomena of Φ750mm large-size Mg-Gd-Y magnesium alloy billet. The electromagnetic characteristics, flow behavior, and temperature distribution during casting process are clearly visualized. The results demonstrate that traditional DC casting process is optimized by applying magnetic fields. For one thing, pulsed magnetic fields (PMF and DPMF) generate larger and faster changing instantaneous Lorentz forces, which induce huge transient impact and oscillation effects on the melt. For another, alternating magnetic fields (AMF and DAMF) have greater time-average Lorentz forces, which can force the melt to flow continuously and steadily. Additionally, differential-phase magnetic fields (DPMF and DAMF) enhance the melt’s axial flow strength while reducing the small vortex generated at the edges, resulting in improved heat transfer efficiency and uniform temperature field. Among those magnetic fields, DPMF shows dual advantages of transient oscillation and homogenized temperature distribution. Based on the present simulated research, the Φ750mm large-sized rare earth Mg-Gd-Y alloy billet with high-quality and non-cracking has been manufactured during DC casting process under DPMF.

Enhancing Scalability and Consistency in Pulsed Electric Field Processing of Microalgae: Integrating Single-Cell Suspension Rheology and Multiphysics Simulation

Emerging extraction technologies such as microsecond pulsed electric field (μsPEF) offer an energy-efficient and gentle method for downstream processing of single cells. However, attaining consistent processing outcomes in continuous PEF systems across different scales is challenging due to variations in cell residence times caused by cell concentration and flow-dependent rheological behavior. This study employed COMSOL Multiphysics® simulations to model rheological changes in high-density heterotrophically grown Auxenochlorella protothecoides microalgae suspensions. The model was designed to precisely estimate residence times for consistent μsPEF treatment and increased processing capacity at high flow rates and cell concentrations. Implementing the simulated residence times into experimental validations achieved consistent treatment outcomes, resulting in 86 ± 4% of cells being permeabilized and increased processing capacity from 21 to 300 mL min-1. Higher cell concentrations led to increased energy input and decreased protein extraction yields, indicating complex underlying permeabilization and diffusion processes during and after treatment. This work advances scalable and consistent μsPEF technology for single-cell downstream processing by applying cell suspension rheology and residence time simulations.

Investigation of pulsed magnetic field treatment to enhance the properties of printed circuit board micro drill

Investigation of pulsed magnetic field treatment to enhance the properties of printed circuit board micro drill

Molecular characterization of ST15 carbapenem-resistant Klebsiella pneumoniae isolated in a single patient

The carbapenem-resistant K. pneumoniae (CRKP) poses a serious threat to antibiotic applicability and public health. During treatment, K. pneumoniae (KP) frequently exhibits shifts in drug-resistant phenotypes, complicating clinical treatment as it transitions from sensitivity to resistance. In this study, we analyzed the clinical and molecular characteristics of drug resistance changes in KP strains isolated from a single patient, and the potential mechanisms underlying these resistance changes. Antimicrobial susceptibility test and string test were conducted to evaluate the resistant and virulent characterization of the strains. Pulsed field gel electrophoresis (PFGE) was used to investigate the homology relationship between the strains. The whole genome sequencing and phylogenetic analysis of 9 representative isolates was also performed. The transfer ability of the drug-resistant plasmid was studied by plasmid conjugation experiment. The transconjugants were verified by PCR amplification of specific genes, antimicrobial susceptibility test and PFGE. Our results revealed that 9 KP strains, isolated from the same patient, exhibited 'resistance-sensitivity-resistance-sensitivity' alternately to carbapenems. The differences in DNA fingerprint bands among the nine KP isolates were ≤ 3, which can be classified as the same PFGE type. Phylogenetic analysis showed that these 9 strains constituted a distinct branch within the phylogenetic tree. All nine KP strains belonged to the ST15-KL19 clone. Six of the strains were classified as CRKP, all of which carried eleven drug resistance genes: oqxB, oqxA, fosA6, aac(3)-lld, blaSHV-28, blaKPC-2, blaOXA-1, mph(A), tet(A), catB3 and aac(6')-lb-cr, mediating drug resistance to quinolones, fosfomycin, aminoglycosides, β-lactam, carbapenems, macrolides and chloramphenicol, belonging to multi-drug resistant bacteria. The carbapenem-resistant plasmid p2-KP3762-1 was found to transfer within species, from CRKP to hypervirulent K. pneumoniae (hvKP) RJF293HA, carbapenem-sensitive K. pneumoniae (CSKP) KP3657 and E. coli C600 at a frequency of (1.19±1.58) ×10-6, (1.09±1.38) ×10-7 and (10.9±9.53) ×10-6 respectively, resulting in the dissemination of carbapenem resistance genes. In this study, KP strains isolated from a single patient exhibited an alternating phenotype of resistant-sensitive-resistant-sensitive to carbapenems. The 9 KP isolates share a high degree of genetic similarity. The plasmid p2-KP3762-1, harboring the carbapenem resistance gene blaKPC-2, may undergo inter-strain and inter-clone transfer via conjugation in the patient during treatment. Furthermore, our findings suggest that the pathogens in this patient are likely to have a common ancestral origin.

Study on the Microstructure and Properties of Al Alloy/Steel CMT Welding–Brazing Joints Under Different Pulse Magnetic Field Intensities

Butt welding experiments on 6061 Al alloy and Q235B steel of 2 mm thickness were conducted using an ER4047F flux-cored wire as the filler metal, after adding a pulsed magnetic field into the process of cold metal transfer (CMT) welding. The effect of the pulsed magnetic field intensity on the macro morphology, microstructure, tensile strength and corrosion resistance of the welding–brazing joint was analyzed. The results showed that when the pulsed magnetic field intensity increased from 0 to 60 mT, the wettability and spreadability of the liquid metal were improved. As a result, the appearance of the Al alloy/steel joint was nice. However, when the pulsed magnetic field intensity was 80 mT, the stability of the arc and the forming quality of the joint decreased, which resulted in a deterioration in the appearance of the joint. A pulsed magnetic field with different intensities did not alter the microstructure of the joint. All of the joint was composed of θ-Fe2(Al,Si)5 and τ5-Al7.2Fe1.8Si at the interface and Al-Si eutectic phase and α-Al solid solution at the weld seam zone. Actually, with the pulsed magnetic field intensity increasing from 0 mT to 60 mT, the IMC thickness in the interfacial layer gradually reduced under the action of electromagnetic stirring. Also, the grain in the weld seam was refined, and elements were distributed uniformly. But when the pulsed magnetic field intensity was 80 mT, the grain in the weld seam began to coarsen, and the intermetallic compound (IMC) thickness was too small, which was unfavorable for the metallurgical bonding of Al alloy and steel. Therefore, with the increase in pulsed magnetic field intensity, the tensile strength of the joints first increased and then decreased, and it reached its maximum of 187.7 MPa with a pulsed magnetic field intensity of 60 mT. Similarly, the corrosion resistance of the joint first increased and then decreased, and it was best when the pulse magnetic field intensity was 60 mT. The Nyquist plot and Bode plot confirmed this result. The addition of a pulsed magnetic field caused less fluctuation in the anode current density, resulting in less localized corrosion of the joint using the scanning vibrating electrode technique (SVET). The XPS analysis showed the Al-Fe-Si compounds replacing the Fe-Al compounds in the joint was the main reason for improving its corrosion resistance under the action of a pulsed magnetic field.

Mechanism and Effects of Multiscale Pulsed Electromagnetic Fields on Rat Glioma Cells

Pulsed electromagnetic field (PMF) treatment based on the dielectric difference between cancer cells and normal cells is a recently discovered novel cancer treatment. However, the mechanism behind PMF irradiation of cancer cells is not clear, and the relationship between the biological effect of cancer cells and PMF irradiation parameters is difficult to predict, leading to difficulties in its application in cancer therapy. In this paper, we designed nanosecond and microsecond PMFs for rat glioma cells (C6) considering different parameters— frequency, rise rate d<i>B</i>/d<i>t</i>, intensity <i>B</i>, action integral Σ<i>B</i>Δ<i>t</i>, and energy action integral Σ<i>B</i><sup>2</sup>Δ<i>t</i>—to accurately describe PMFs. The results point to a statistically significant window effect and cumulative effect of PMFs on cancer cell viability. In particular, the results of nanosecond PMFs showed that low-frequency and low-intensity electromagnetic fields are more likely to inhibit the proliferation of C6 cells. At a frequency of 1 Hz, C6 cell viability was inhibited by about 10%–15%. Furthermore, when the intensity was 0.353 mT, nanosecond PMFs showed an inhibitory effect, except at 10 Hz. The effective inhibition values of the magnetic field parameters d<i>B</i>/d<i>t</i> (T/s), <i>Bt</i> (mT·s), and <i>B</i><sup>2</sup><i>t</i> (mT<sup>2</sup>·s) after microsecond PMFs were [4.14 × 10<sup>3</sup>, 5.65 × 10<sup>4</sup>], [1.18 × 10<sup>-2</sup>, 4.51 × 10<sup>-2</sup>], and [1.28, 11.30], respectively. It is noted that the rise rate (d<i>B</i>/d<i>t</i>) of PMFs plays a major role in inhibiting cancer cell proliferation. Furthermore, when the difference of d<i>B</i>/d<i>t</i> is small, the intensity becomes the main factor affecting cancer cell viability. Overall, this study establishes theoretical and experimental foundations for the study of electromagnetic biological effects and their clinical applications.