Low-frequency pulsed electromagnetic field pretreated bone marrow-derived mesenchymal stem cells promote the regeneration of crush-injured rat mental nerve

Bone marrow-derived mesenchymal stem cells （BMSCs） have been shown to promote the regeneration of injured peripheral nerves. Pulsed electromagnetic field （PEMF） reportedly promotes the proliferation and neuronal differentiation of BMSCs. Low-frequency PEMF can induce the neuronal differentiation of BMSCs in the absence of nerve growth factors. This study was designed to investigate the effects of low-frequency PEMF pretreatment on the proliferation and function of BMSCs and the effects of low-frequency PEMF pre-treated BMSCs on the regeneration of injured peripheral nerve using in vitro and in vivo experiments.In in vitro experiments, quantitative DNA analysis was performed to determine the proliferation of BMSCs, and reverse transcription-polymerase chain reaction was performed to detect S100 （Schwann cell marker）, glial fibrillary acidic protein （astrocyte marker）, and brain-derived neurotrophic factor and nerve growth factor （neurotrophic factors） mRNA expression. In the in vivo experiments, rat models of crush-injured mental nerve established using clamp method were randomly injected with low-frequency PEMF pretreated BMSCs, unpretreated BMSCs or PBS at the injury site （1 × 106 cells）. DiI-labeled BMSCs injected at the injury site were counted under the fluorescence microscope to determine cell survival. One or two weeks after cell injection, functional recovery of the injured nerve was assessed using the sensory test with von Frey filaments. Two weeks after cell injection, axonal regeneration was evaluated using histomorphometric analysis and retrograde labeling of trigeminal ganglion neurons. In vitro experiment results revealed that low-frequency PEMF pretreated BMSCs proliferated faster and had greater mRNA expression of growth factors than unpretreated BMSCs. In vivo experiment results revealed that compared with injection of unpretreated BMSCs, injection of low-frequency PEMF pretreated BMSCs led to higher myelinated axon count and axon density and more DiI-labeled neurons in the trigeminal ganglia, contributing to rapider functional recovery of injured mental nerve. These findings suggest that low-frequency PEMF pretreatment is a promising approach to enhance the efficacy of cell therapy for peripheral nerve injury repair.

The Effects of High-intensity Pulsed Electromagnetic Field on Proliferation and Differentiation of Neural Stem Cells of Neonatal Rats in vitro

The effects of high-intensity pulsed electromagnetic stimulation （HIPEMS） on proliferation and differentiation of neonatal rat neural stem cells in vitro were investigated. Neural stem cells derived from neonatal rats were exposed to 0.1 Hz, 0.5–10 Tesla （T） [8 groups of B–I, respectively], 5 stimuli of HIPEMF. The sham exposure controls were correspondingly established. Inverted phase contrast microscope was used to observe the cultured cells, MTT assay to detect the viability of the cells as expressed by absorbance （A） value, and flow cytometry to measure differentiation of neural stem cells. The results showed that A values of neural stem cells in both 3.0 T and 4.0 T groups were significantly higher than the other groups 24 to 168 h post HPEMS, indicating a strong promotion of the growth of neural stem cells （P〈0.05）. The A values of neural stem cells in the 6.0 T, 8.0 T, and 10.0 T groups were lower than the sham exposure control group, indicating a restraint of the growth of neural stem cells. The rate of neuron-specific enolase-positive neurons revealed by flow cytometry in HPEMS groups was the same as that in control group （P〉0.05）. It was suggested that 0.1 Hz, 5 pulses stimulation of HPEMS within certain scale of intensity （0.5–10.0 T）, significantly promoted the growth of neural stem cells with the rational intensity being 4.0 T.

Role of pulsed electromagnetic fields after joint replacements

Although the rate of patients reporting satisfaction is generally high after joint replacement surgery, up to 23% after total hip replacement and 34% after total knee arthroplasty of treated subjects report discomfort or pain 1 year after surgery. Moreover, chronic or subacute inflammation is reported in some cases even a long time after surgery. Another open and debated issue in prosthetic surgery is implant survivorship, especially when related to good prosthesis bone ingrowth. Pulsed Electro Magnetic Fields(PEMFs) treatment, although initially recommended after total joint replacement to promote bone ingrowth and to reduce inflammation and pain, is not currently part of usual clinical practice. The purpose of this review was to analyze existing literature on PEMFs effects in joint replacement surgery and to report results of clinical studies and current indications. We selected all currently available prospective studies or RCT on the use of PEMFs in total joint replacement with the purpose of investigating effects of PEMFs on recovery, pain relief and patients’ satisfaction following hip, knee or shoulder arthroplasty. All the studies analyzed reported no adverse effects, and good patient compliance to the treatment. The available literature shows that early control of joint inflammation process in the first days after surgery through the use of PEMFs should be considered an effective completion of the surgical procedure to improve the patient’s functional recovery.

Effect of pulsed electromagnetic frequency on the microstructure, wear and solid erosion resistance of CrAlN coatings deposited by arc ion plating

In this work,the chromium aluminum nitride(CrAlN)coatings were prepared on TC11 titanium alloy by composite magnetic field cathodic arc ion plating with controllable pulse electromagnetic combined with permanent magnet.The effects of electromagnetic frequency on the morphology,microstructure,nano-hardness and elastic modulus of the coatings were investigated by scanning electron microscope(SEM),X-ray diffraction(XRD)and nano-indenter.This paper has mainly studied the influence of CrAlN coatings which are prepared at various electromagnetic frequencies on the wear and erosion resistance through a series of wear and solid particle erosion experiments.It was found that the deposition rate of CrAlN coatings increases with the increase of electromagnetic frequency.And CrAlN coatings all preferentially grew along the(111)crystal plane.At 16.7 Hz,with the increase of pulsed electromagnetic frequency,the hardness is the highest(23.6 GPa)and the adhesion is the highest(41.5 N).In addition,the coating deposition exhibited the best wear and solid erosion resistance at 16.7 Hz and 33.3 Hz,the friction coefficient is about 0.35,and the erosion rate is about 0.2μm/g at 30°and less than 1μm/g at 90°,respectively.These results indicate that the CrAlN coating formed at an appropriate pulsed electromagnetic frequency can achieve excellent mechanical properties,wear and solid erosion resistance.

Pulsed electromagnetic field stimulation enhances neurite outgrowth in neural cells and modulates inflammation in macrophages

Nerve regeneration following traumas remains an unmet challenge.The application of pulsed electromagnetic field(PEMF)stimulation has gained traction for a minimally invasive regeneration of nerves.However,a sys-tematic exploration of different PEMF parameters influencing neuron function at a cellular level is not available.In this study,we exposed neuroblastoma F11 cells to PEMF to trigger beneficial effects on neurite outgrowth.Different carrier frequencies,pulse repetition frequencies,and duty cycles were screened with a custom ad hoc setup to find the most influential parameters values.A carrier frequency of 13.5 MHz,a pulse repetition frequency of 20 Hz,and a duty cycle of 10%allowed maximal neurite outgrowth,with unaltered viability with respect to non-stimulated controls.Furthermore,in a longer-term analysis,such optimal conditions were also able to in-crease the gene expression of neuronal expression markers NeuN and Tuj-1 and transcription factor Ngn1.Finally,the same optimal stimulation conditions were also applied to THP-1 macrophages,and both pro-inflammatory(TNF-α,IL-1β,IL-6,IL-8)and anti-inflammatory cytokines(IL-10,CD206)were analyzed.The optimal PEMF stimulation parameters did not induce differentiation towards an M1 macrophage phenotype,decreased IL-1β and IL-8 gene expression,decreased TNF-α and IL-8 cytokine release in M1-differentiated cells,increased IL-10 and CD206 gene expression,as well as IL-10 cytokine release in M0 cells.The specific PEMF stimulation regime,which is optimal in vitro,might have a high potential for a future in vivo translation targeting neural regeneration and anti-inflammatory action for treating peripheral nerve injuries.

Enhancing cartilage repair with optimized supramolecular hydrogel-based scaffold and pulsed electromagnetic field

Functional tissue engineering strategies provide innovative approach for the repair and regeneration of damaged cartilage.Hydrogel is widely used because it could provide rapid defect filling and proper structure support,and is biocompatible for cell aggregation and matrix deposition.Efforts have been made to seek suitable scaffolds for cartilage tissue engineering.Here Alg-DA/Ac-β-CD/gelatin hydrogel was designed with the features of physical and chemical multiple crosslinking and self-healing properties.Gelation time,swelling ratio,biodegradability and biocompatibility of the hydrogels were systematically characterized,and the injectable self-healing adhesive hydrogel were demonstrated to exhibit ideal properties for cartilage repair.Furthermore,the new hydrogel design introduces a pre-gel state before photo-crosslinking,where increased viscosity and decreased fluidity allow the gel to remain in a semi-solid condition.This granted multiple administration routes to the hydrogels,which brings hydrogels the ability to adapt to complex clinical situations.Pulsed electromagnetic fields(PEMF)have been recognized as a promising solution to various health problems owing to their noninvasive properties and therapeutic potentials.PEMF treatment offers a better clinical outcome with fewer,if any,side effects,and wildly used in musculoskeletal tissue repair.Thereby we propose PEMF as an effective biophysical stimulation to be 4th key element in cartilage tissue engineering.In this study,the as-prepared Alg-DA/Ac-β-CD/gelatin hydrogels were utilized in the rat osteochondral defect model,and the potential application of PEMF in cartilage tissue engineering were investigated.PEMF treatment were proven to enhance the quality of engineered chondrogenic constructs in vitro,and facilitate chondrogenesis and cartilage repair in vivo.All of the results suggested that with the injectable self-healing adhesive hydrogel and PEMF treatment,this newly proposed tissue engineering strategy revealed superior clinical potential for cartilage defect treatment.

Electromagnetic pulses produced by a picosecond laser interacting with solid targets

A high-power laser ablating solid targets induces giant electromagnetic pulses(EMPs),which are intimately pertinent to laser parameters,such as energy and pulse width.In this study,we reveal the features of EMPs generated from a picosecond(ps)laser irradiating solid targets at the SG-Ⅱpicosecond petawatt(PSPW)laser facility.The laser energy and pulse,as well as target material and thickness,show determinative effects on the EMPs’amplitude.More intense EMPs are detected behind targets compared to those at the other three positions,and the EMP amplitude decreases from 90.09 kV/m to 17.8 kV/m with the gold target thickness increasing from 10μm to 20μm,which is suppressed when the laser pulse width is enlarged.The results are expected to provide more insight into EMPs produced by ps lasers coupling with targets and lay the foundation for an effective EMP shielding design in high-power laser infrastructures.

Generation and regulation of electromagnetic pulses generated by femtosecond lasers interacting with multitargets

Ultrashort and powerful laser interactions with a target generate intense wideband electromagnetic pulses(EMPs).In this study,we report EMPs generated by the interactions between petawatt(30 fs,1.4×10^(20) W/cm^(2))femtosecond(fs)lasers with metal flat,plastic flat,and plastic nanowire-array(NWA)targets.Detailed analyses are conducted on the EMPs in terms of their spatial distribution,time and frequency domains,radiation energy,and protection.The results indicate that EMPs from metal targets exhibit larger amplitudes at varying angles than those generated by other types of targets and are enhanced significantly for NWA targets.Using a plastic target holder and increasing the laser focal spot can significantly decrease the radiation energy of the EMPs.Moreover,the composite shielding materials indicate an effective shielding effect against EMPs.The simulation results show that the NWA targets exert a collimating effect on thermal electrons,which directly affects the distribution of EMPs.This study provides guidance for regulating EMPs by controlling the laser focal spot,target parameters,and target rod material and is beneficial for electromagnetic-shielding design.

Spatial and temporal evolution of electromagnetic pulses from solid target irradiated with multi-hundred-terawatt laser pulse inside target chamber

Giant electromagnetic pulses(EMPs) induced by high-power laser irradiating solid targets interfere with various experimental diagnoses and even damage equipment,so unveiling the evolution of EMPs inside the laser chamber is crucial for designing effective EMP shielding.In this work,the transmission characteristics of EMPs as a function of distances from the target chamber center(TCC) are studied using B-dot probes.The mean EMP amplitude generated by picosecond laser-target interaction reaches 561 kV m^(-1),357 kV m^(-1),395 kV m^(-1),and 341 kV m^(-1)at 0.32 m,0.53 m,0.76 m,and 1 m from TCC,which decreases dramatically from 0.32 m to 0.53 m.However,it shows a fluctuation from 0.53 m to 1 m.The temporal features of EMPs indicate that time-domain EMP signals near the target chamber wall have a wider full width at half maximum compared to that close to TCC,mainly due to the echo oscillation of electromagnetic waves inside the target chamber based on simulation and experimentation.The conclusions of this study will provide a new approach to mitigate strong electromagnetic pulses by decreasing the echo oscillation of electromagnetic waves inside the target chamber during laser coupling with targets.

Effect and mechanism of on-chip electrostatic discharge protection circuit under fast rising time electromagnetic pulse

The electrostatic discharge(ESD)protection circuit widely exists in the input and output ports of CMOS digital circuits,and fast rising time electromagnetic pulse(FREMP)coupled into the device not only interacts with the CMOS circuit,but also acts on the protection circuit.This paper establishes a model of on-chip CMOS electrostatic discharge protection circuit and selects square pulse as the FREMP signals.Based on multiple physical parameter models,it depicts the distribution of the lattice temperature,current density,and electric field intensity inside the device.At the same time,this paper explores the changes of the internal devices in the circuit under the injection of fast rising time electromagnetic pulse and describes the relationship between the damage amplitude threshold and the pulse width.The results show that the ESD protection circuit has potential damage risk,and the injection of FREMP leads to irreversible heat loss inside the circuit.In addition,pulse signals with different attributes will change the damage threshold of the circuit.These results provide an important reference for further evaluation of the influence of electromagnetic environment on the chip,which is helpful to carry out the reliability enhancement research of ESD protection circuit.

Clinical update of pulsed electromagnetic fields on osteoporosis

Objective To understand the effects of low-frequency pulsed electromagnetic fields （PEMFs） on chronic bony pain, bone mineral density （BMD）, bone strength and biochemical markers of bone metabolism in the patients of osteoporosis. Data sources Using the key words “pulsed electromagnetic fields” and “osteoporosis”, we searched the PubMed for related studies published in English from January 1996 to December 2007. We also searched the China National Knowledge Infrastructure （CNKI） for studies published in Chinese from January 1996 to December 2007.Study selection Inclusion criteria： （1） all articles which referred to the effects of low-frequency pulsed magnetic fields on osteoporosis either in primary osteoporosis or secondary osteoporosis; （2） either observational studies or randomized controlled studies. Exclusion criteria： （1） articles on experimental studies about osteoporosis; （2） repetitive studies; （3） case reports; （4） meta analysis.Results Totally 111 related articles were collected, 101 of them were published in Chinese, 10 were in English. Thirty-four were included and the remaining 84 were excluded.Conclusions Low-frequency PEMFs relieves the pain of primary osteoporosis quickly and efficiently, enhances bone formation and increases BMD of secondary osteoporosis. But the effects of PEMFs on bone mineral density of primary osteoporosis and bone resorption were controversial.

Metallurgical Applications of Pulsed Electromagnetic Field

This paper reviews the current applied research of the pulsed electromagnetic field in the metallurgical area of solidification,plastic deformation and electro-deposition.The possibilities of developing the field applications are analyzed when viewing from the processes of the metallurgy industry.It covers refining grain in the solidification process under the pulsed electromagnetic field,rolling of the thin plate deformation with the help of the electro-plastic effects by the pulsed power supplies and pulsed plating of pure metals or alloys onto the surface of the running steel strip.

Far-zone behaviors of scattering-induced statistical properties of partially polarized spatially and spectrally partially coherent electromagnetic pulsed beam

In this study, we explore the far-zero behaviors of a scattered partially polarized spatially and spectrally partially coherent electromagnetic pulsed beam irradiating on a deterministic medium. The analytical formula for the cross-spectral density matrix elements of this beam in the spherical coordinate system is derived. Within the framework of the first-order Born approximation, the effects of the scattering angle θ, the source parameters (i.e., the pulse duration T0 and the temporal coherence length Tcxx), and the scatterer parameter (i.e., the effective width of the medium σR) on the spectral density, the spectral shift, the spectral degree of polarization, and the degree of spectral coherence of the scattered source in the far-zero field are studied numerically and comparatively. Our work improves the scattering theory of stochastic electromagnetic beams and it may be useful for the applications involving the interaction between incident light waves and scattering media.

Pulse Electromagnetic Effect on Metal Melts

The aim of the work was the study of the effect of NEMP （nanosecond electromagnetic pulses） on steel properties. Steel treatment was performed under the workshop conditions. The mechanical properties and the microstructure of the experimental samples and samples prepared by usual way were analyzed. The treatment of metal melt with nanosecond electromagnetic pulses at the crystallization stage makes it possible to change mechanical properties of metal and its structure.

Cable coupling response in metal cavity under X-ray irradiation

This study investigates the coupling response of cables inside a metal cavity under X-ray irradiation using the finite-difference time-domain method,particle simulation method,and transmission-line equation to solve the electromagnetic field inside the cavity and load voltage at the cable terminal under X-ray excitation.The results show that under a strong ionizing radiation environment of 1 J/cm^(2),a strong electromagnetic environment is generated inside the cavity.The cable shielding layer terminal couples a voltage of 15.32 V,whereas the core wire terminal couples a voltage of 0.31 V.Under strong X-ray irradiation,the metal cavity not only fails to provide electromagnetic shielding,but also introduces new electromagnetic interference.This study also provides a method for reducing the number of emitted electrons by adding low-Z materials,which can effectively reduce the coupled electric field and voltage.

Microstructure Refinement of Al-5Ti-B Grain Refiner with Electromagnetic Energy

The influence of the electromagnetic energy on the microstructure of Al-5Ti-B grain reflner was discussed.In this study,the electromagnetic energy was applied above the liquid phase line temperature.Compared with Al-5Ti-B without electromagnetic energy applied,the experimental results show that the size of secondary particles is reduced and its size distribution becomes more uniform.Simultaneously,the secondary phase particles are uniformly spread in the matrix response to the electromagnetic energy.Moreover,when adding Al-5Ti-B with electromagnetic energy to the pure aluminum melt,it is clear that the electromagnetic energy has a signiflcantly impact on reflning properties of Al-5Ti-B.The mean size of pure aluminum is reduced by 27.6%in maximum with more uniform size distribution.The change in the microstructure is attributed to the electromagnetic energy changes the melt structure.With the electromagnetic energy entry into the system,the electromagnetic energy reduces the size of atomic clusters and increases the number of atomic clusters,thus the number of nuclei increases.

Clinical efficacy of electromagnetic field therapy combined with traditional Chinese pain-reducing paste in myofascial pain syndrome

BACKGROUND Pulsed electromagnetic field(PEMF)therapy is widely used to treat myofascial pain syndrome(MPS).Damp-clearing and pain-reducing paste(DPP)comprises medical herbs and has been a traditional method of reducing myofascial pain in China for a long time,and it is usually administered with heating.However,the synergistic effect of PEMF therapy on heating-DPP in patients with MPS is unclear.AIM To investigate the synergistic effect of PEMF therapy plus heating-DPP in lumbar MPS.METHODS This double-blind,randomized,placebo-controlled trial was conducted on 120 patients with lumbar MPS who were randomly divided into an experimental group(EG,n=60)and a control group(CG,n=60).Patients in both groups were treated with heating-DPP combined with PEMF therapy;however,the electromagnetic function of the therapeutic apparatus used in the CG was disabled.Each treatment lasted for 20 min and was applied five times a week for two weeks.The short-form McGill Pain Questionnaire was applied at five time points:pretest,end of the first and second weeks of treatment,and end of the first and fourth week after completing treatment.Visual analog scale(VAS),present pain intensity index(PPI),and pain rating index(PRI;total,affective pain,and sensory pain scores)scores were then analyzed.RESULTS Compared with the CG,the VAS,PPI and PRI scores(total,affective pain and sensory pain scores)in the EG were significantly lower after treatment and during follow-up.CONCLUSION PEMF therapy combined with heating-DPP showed better efficacy than heating-DPP alone in reducing the overall intensity of pain and sensory and affective pain.

Detrimental Effect of Electromagnetic Pulse Exposure on Permeability of In Vitro Blood-brain-barrier Model

Objective To study the effect of electromagnetic pulse （EMP） exposure on permeability of in vitro blood-brain-barrier （BBB） model. Methods An in vitro BBB model, established by co-culturing brain microvascular endothelial cells （BMVEC） and astroglial cells （AC） isolated from rat brain, was exposed to EMP at 100 kV/m and 400 kV/m, respectively. Permeability of the model was assayed by measuring the transendothelial electrical resistance （TEER） and the horseradish peroxidase （HRP） transmission at different time points. Levels of BBB tight junction-related proteins were measured at O, 1, 2, 4, 8, 12, 16, 20, 24 h after EMP exposure by Western blotting. Results The TEER level was lower in BBB model group than in control group at 12 h after EMP, exposure which returned to its normal level at 24 h. The 24 h recovery process was triphasic and biphasic respectively after EMP exposure at 100 kV/m and 400 kV/m. Following exposure to 400 kV/m EMP, the HRP permeability increased at 1-12 h and returned to its normal level at 24 h. Western blotting showed that the claudin-5 and ZO-1 protein levels were changed after EMP exposure. Conclusion EMP exposure at 100 kV/m and 400 kV/m can increase the permeability of in vitro BBB model and BBB tight junction-related proteins such as ZO-1 and claudin-5 may change EMP-induced BBB permeability.

Effect of Electromagnetic Pulse Exposure on Brain Micro Vascular Permeability in Rats

Objective To observe the effect of electromagnetic pulse (EMP) exposure on cerebral micro vascular permeability in rats. Methods The whole-body of male Sprague-Dawley rats were exposed or sham exposed to 200 pulses or 400 pulses (1 Hz) of EMP at 200 kV/m. At 0.5, 1, 3, 6, and 12 h after EMP exposure, the permeability of cerebral micro vascular was detected by transmission electron microscopy and immunohistochemistry using lanthanum nitrate and endogenous albumin as vascular tracers, respectively. Results The lanthanum nitrate tracer was limited to the micro vascular lumen with no lanthanum nitrate or albumin tracer extravasation in control rat brain. After EMP exposure, the lanthanum nitrate ions reached the tight junction, basal lamina and pericapillary tissue. Similarly, the albumin immunopositive staining was identified in pericapillary tissue. The changes in brain micro vascular permeability were transient, the leakage of micro vascular vessels appeared at 1 h, and reached its peak at 3 h, and nearly recovered at 12 h, after EMP exposure. In addition, the leakage of micro vascular was more obvious after exposure of EMP at 400 pulses than after exposure of EMP at 200 pulses. Conclusion Exposure to 200 and 400 pulses (1 Hz) of EMP at 200 kV/m can increase cerebral micro vascular permeability in rats, which is recoverable.

Development of gated fiber detectors for laser-induced strong electromagnetic pulse environments

With the development of laser technologies,nuclear reactions can happen in high-temperature plasma environments induced by lasers and have attracted a lot of attention from different physical disciplines.However,studies on nuclear reactions in plasma are still limited by detecting technologies.This is mainly due to the fact that extremely high electromagnetic pulses(EMPs)can also be induced when high-intensity lasers hit targets to induce plasma,and then cause dysfunction of many types of traditional detectors.Therefore,new particle detecting technologies are highly needed.In this paper,we report a recently developed gated fiber detector which can be used in harsh EMP environments.In this prototype detector,scintillating photons are coupled by fiber and then transferred to a gated photomultiplier tube which is located far away from the EMP source and shielded well.With those measures,the EMPs can be avoided which may result that the device has the capability to identify a single event of nuclear reaction products generated in laser-induced plasma from noise EMP backgrounds.This new type of detector can be widely used as a time-of-flight(TOF)detector in high-intensity laser nuclear physics experiments for detecting neutrons,photons,and other charged particles.