Effects of Exposure to Extremely Low Frequency Electro-magnetic Fields on Circadian Rhythms and Distribution of Some Leukocyte Differentiation Antigens in Dairy Cows

Objective To investigate the effects of extremely low frequency magnetic and electric fields （ELFEMFs） emitted from 380 kV transmission lines on some leukocyte differentiation antigens in dairy cows. Methods The study was carded out in 5 cows exposed to 1.98-3.28 μT of ELFEMFs and in 5 control cows exposed to 0.2-0.7 μT of ELFEMFs. Following haematological and immunologic parameters were measured in both groups： WBC, CD45R, CD6, CD4, CD8, CD21, and CD11B leukocyte antigen expression. Results Some of the haematological and immunologic parameters under investigation were similar in both groups. However, CD8 （T lymphocyte surface antigen） was higher in the exposed group （1.35 ±0.120 vs 0.50 ±0.14×10^3/mL）. Furthermore, the CD4/CD8 ratio （0.84 ±0.05 and 2.19±0.16 for exposed and not exposed cows respectively） and circadian rhythm were different between the two groups. Conclusion Exposure to ELFEMFs is responsible of the abnormal temporal variations and distribution of some haematological and immunological parameters in dairy cows.

EXTREMELY LOW FREQUENCY MAGNETIC FIELD SUSCEPTIBILITY OF VISUAL DISPLAY UNITS

Extremely low frequency (ELF) magnetic field susceptibility is an index of visual display unit (VDU) quality and performance. This paper provided field measured data on the susceptibility for a large variety of VDUs. A test rig was built to study the susceptibility of VDUs to magnetic fields at fundamental and third harmonic frequencies. It was found that the susceptibility level is largely dependent on refresh rate of the VDU and the orientation of the external ELF field. It was also found that the VDU susceptibility is significantly increased in the presence of harmonic frequency magnetic fields. About 30% of the tested samples have susceptibility levels higher than that stated in IEC 1000-4-8 standard.

THE INFLUENCE OF LOW-FREQUENCY VARYING MAGNETIC FIELDON THE PULSATILE FLOW IN A RIGID ROUND TUBE

In this paper, the analytic solution of the dynamical equation of the pulsatile flow in a rigid round tube under the low-frequency varying magnetic field is obtained. The velocity distribution and the flow impedance are calculated. The results of e valuable for understanding the influence of low-frequency varying magnetic field on hemodynamics and its clinical application.

Association between Childhood Leukaemia and Exposure to Power-frequency Magnetic Fields in Middle Europe

Abstract Objective Higher levels of exposure to extremely low-frequency magnetic fields （ELF-MF） are associated with a slightly increased risk of childhood leukaemia. Compared with more-developed Western countries, higher exposure levels are evident in the Czech Republic, probably because of the different types of housing. In light of this, we aimed to examine the association between ELF-MF exposure and childhood leukaemia in the Czech Republic. Methods We conducted a paired case-control study. The cases （children with leukaemia） were age- sex- and permanent residence-matched to controls （children without leukaemia）. Although this limited potential bias and confounding, it also limited our number of participants. Results The matched analyses included 79 case-control pairs. No significant association between ELF-MF exposure and childhood leukaemia was observed for exposures over 0.2 μT （odds ratio [0R]=0.93, confidence interval [Cl]=0.45-1.93）, 0.3 μT （0R=0.77, Cl=0.34-1.75）, or 0.4 μT （OR=0.9, Cl=0.37-2.22）. Conclusion Despite higher levels of exposure in Middle and Eastern Europe, no indication of an association between ELF-MF exposure and childhood leukaemia was determined. This in contrast to the findings of previous studies conducted in different countries.

Combined Effects of 50 Hz Magnetic Field and Magnetic Nanoparticles on the Proliferation and Apoptosis of PC12 Cells

Objective To investigate the bioeffects of extremely low frequency （ELF） magnetic field （MF） （50 Hz, 400 μT） and magnetic nanoparticles （MNPs） via cytotoxicity and apoptosis assays on PC12 cells. Methods MNPs modified by SiO2 （MNP-SiO2） were characterized by transmission electron microscopy （TEM）, dynamic light scattering and hysteresis loop measurement. PC12 cells were administrated with MNP-SiO2 with or without MF exposure for 48 h. Cytotoxicity and apoptosis were evaluated with MTI- assay and annexin V-FITC/PI staining, respectively. The morphology and uptake of MNP-SiO2 were determined by TEM. MF simulation was performed by Ansoft Maxwell based on the finite element method. Results MNP-SiO2 were identified as -20 nm （diameter） ferromagnetic particles. MNP-SiO2 reduced cell viability in a dose-dependent manner. MF also reduced cell viability with increasing concentrations of MNP-SiO2. MNP-SiO2 alone did not cause apoptosis in PC12 cells; instead, the proportion of apoptotic cells increased significantly under MF exposure and increasing doses of MNP-SiO2. MNP-SiO2 could be ingested and then cause a slight change in cell morphology. Conclusion Combined exposure of MF and MNP-SiO2 resulted in remarkable cytotoxicity and increased apoptosis in PC12 cells. The results suggested that MF exposure could strengthen the MF of MNPs, which may enhance the bioeffects of ELF MF.

Effects of electromagnetic field intensity on as-cast microstructures and mechanical properties of Al-Zn-Mg-Cu-Zr alloy

Al-Zn-Mg-Cu-Zr ingots with diameter of 200 mm were made by low frequency electromagnetic casting (LFEC) and conventional direct chill (DC) casting process. The results show that under the low frequency electromagnetic field (25 Hz, 32 mT) the microstructures of LFEC ingot from the border to the center on the cross section are all equiaxed grains, and the grains are much finer and more uniform than that of DC ingot. The magnetic flux density plays an important role in the microstructure formation of LFEC ingots. With increasing the magnetic flux density from 0 mT to 32 mT, grains become finer (from about 120 urn to 30 urn) and more uniform. While, with increasing the magnetic flux density from 32 mT to 46 mT, the grains change much slowly. In the range of experimental parameters, the optimum magnetic flux density for LFEC process is found to be 32 mT.

Isotope effects of plasma chemical carbon oxidation in a magnetic field

The influence of different factors on the plasma chemical reactions is widely studied today. However, insufficient consideration is given to the research of paramagnetic phenomena which takes place in plasma systems. The results of modeling the process of redistribution carbon isotopes between different phases while oxidizing it in high-frequency low-temperature plasma in an external magnetic field are shown in the article. The equilibrium concentrations of components involved in the oxidation process in a plasma system are defined. A principle possibility of isotope-selective plasma chemical reactions in a magnetic field was experimentally determined. The increase of concentration of 13C in the gas phase up to 1.3 times relative to natural abundance was obtained. It was found that the content of the carbon heavy isotope in the gas phase depends on the magnetic field action area. The best results were achieved with the combination of magnetic field impact area and the priority area of the appearance of plasma chemical reactions products.

Experimental studies on extremely low frequency pulsed magnetic field inhibiting sarcoma and enhancing cellular immune functions

The previous observation with an electron microscope showed that extremely low frequency (ELF) pulsed magnetic field (PMF) (with the maximum intensity of 0. 6-2. 0 T, gradient of 10-100 T. M-1, pulse width of 20-200 ms and frequency of 0. 16-1. 34 Hz) inhibited the growth of S-180 sarcoma in mice and enhanced the ability of immune cell’s dissolving sarcoma cells. In this study, the DNA contents of nuclei were assayed by using Faulgen Staining method. With an electron microscope and cell stereoscopy technology it was observed that magnetic field affected the sarcoma cell’s metabolism, lowered its malignancy, and restrained its rapid and heteromorphic growth. The magnetic field enhanced the cellular immune ability and the reaction of lymphocytes and plasma. Since ELF pulsed magnetic fields can inhibit the growth of sarcomas and enhance the cellular immune ability, it is possible to use it as a new method to treat cancer.

Effects of extremely low frequency magnetic field on anxiety level and spatial memory of adult rats

Background As the widespread use of electric devices in modern life, human are exposed to extremely low frequency magnetic fields （ELF MF） much more frequently than ever. Over the past decades, a substantial number of epidemiological and experimental studies have demonstrated that ELF MF （50 Hz） exposure is associated with increased risk of various health effects. The present study examined the effects of chronic exposure to ELF MF on anxiety level and spatial memory of adult rats. Methods The 50-Hz ELF MF was used during the whole experimental procedures and the value of magnetic field （MF） was set to 2 mT. Adult rats were divided randomly to control, MF 1 hour and MF 4 hours group. Anxiety-related behaviors were examined in the open field test and the elevated plus maze; changes in spatial learning and memory were determined in Morris water maze aRer 4 weeks of daily exposure. Results Rats in MF 4 hours group had increased anxiety-like behaviors with unaltered locomotor activity. In the Morris water maze test, rats had reduced latency to find the hidden platform and improved long-term memory of former location of platform without changes in short-term memory and locomotor activity. Conclusion Chronic ELF MF exposure has anxiogenic effect on rats, and the promoting effects on spatial learning and long-term retention of spatial memory.

ULF electric and magnetic anomalies accompanying the cracking of rock sample

The anomalies of electric-magnetic field and self-potential before earthquakes are important precursory phenom-ena. A simulating experiment study on the variations in ultra-low frequency (ULF) magnetic field and self-poten-tial during rock cracking was carried out in a magnetic field-free space. The results revealing in detail the whole process of the occurrences of electric and magnetic anomalies are significant for understanding the microscopic mechanism of ULF electric and magnetic signals. The experiment indicated that at the initial stage the slow changes in strain, self-potential and magnetic field with small amounts appeared firstly near the source of initial cracking, and then extended as the crack developed on. In the time domain, the self-potential anomaly emerged first and ULF magnetic field changes arose then. The shape of the ULF electric and magnetic anomaly varied ob-viously in early-, mid- and late-term of the test. The authors attributed the pulse-like changes of self-potential to the generation and movement of the accumulated electric charges during the cracking caused by charge separation on the crack tips within the sample. While the magnetic pulses of shorter-period at the last stage of the test, may be induced by instantaneous electric current of the accumulated charge during the cracking acceleration. The technical method and the observational results of this experiment are given in detail and the microscopic mechanism of elec-tric and magnetic precursors before earthquake are discussed in the present paper as well.

Parametric instability of a liquid metal sessile drop under the action of low-frequency alternating magnetic fields

A 2-D mathematical model is developed in order to simulate a parametric electromagnetic instability oscillation process of a liquid metal droplet under the action of low frequency magnetic field. The Arbitrary Lagrangian-Eulerian （ALE） method and weak form constraint boundary condition are introduced in this model for implementation of the surface tension and electromagnetic force on liquid droplet free surface. The results of the numerical calculations indicate the appearance of various regimes of oscillation. It is found that according to the magnetic field frequency various types of oscillation modes may be found. The oscillation is originated from an instability phenomenon. The stability diagram of liquid metal droplet in the parameter space of magnetic frequency and magnetic flux density is determined numerically. The diagram is very similar to that found in the so-called parametric instability.

LOW FREQUENCY EXTENDED RADIO SOURCES——MAGNETIC FIELD STRENGTH AND CLASSIFICATION ATTEMPT

Using very recently published X-ray and low frequency radio data we have calculated thelower limit of the magnetic field and several other related quantities for 25 clusters of galaxies（which are classified into 'normal', distant and steep spectrum clusters） and 12 radiogalaxies. Our main results are as follows: （1）The magnetic field in the extended lobes of radio galaxies is larger than 10-6 G.Thus radio galaxies, whether they belong to clusters or not, emit few X-rays through theinverse Compton effect. （2）The low frequency radio emission from clusters can be divided into two components:one or several radio galaxies, and an extended halo where the magnetic field is about 10-8G, and where inverse Compton X-rays are most probably emitted. （3）Our sample of distant clusters is biased towards high radio luminosity and givesresults comparable to those obtained for radio galaxies. This can naturally be explained bythe fact that the radio galaxy component daminates the radio emission. （4）In steep spectrum clusters, the equipartition magnetic field is the same as that in'normal' clusters, but the lower limit of the magnetic field has a rather high value andseems to increase with the spectral indcx. We explain this as follows: a high frequencyturnover can occur hi the weak intraculuster magnetic field; the extrapolation of the power lawelectron spectrum is then incorrect, and the magnetic field; the extrapolation of the power lawvalue.

低频脉冲磁场慢性暴露对健康成年股四头肌收缩力及形态的影响

背景:目前已有关于低频脉冲磁场对骨骼肌结构形态影响研究发现了骨骼肌质量变化,但对接受慢性暴露后的形态变化未见相关研究。目的:观察低频脉冲磁场慢性暴露对腿部股四头肌最大自主收缩力与形态指标的影响,为使用该技术作为肌肉功能改善策略提供组织形态变化的参考依据。方法:招募普通健康受试者70名,随机分为接受磁场刺激的试验组与进行假治疗的对照组,每组35名,试验时长共计4周,试验组受试者每隔48 h进行1次15 min的低频脉冲磁刺激干预,对照组进行假治疗,干预间隔与时长与试验组一致,干预4周后观察不同组别受试者股四头肌最大自主收缩力值变化,利用B型超声影像作为评估手段,观察肌肉厚度、肌肉横截面积及羽状角指标的变化。结果与结论:①经过4周的低频脉冲磁场慢性暴露,68名受试者完成试验,试验组受试者股四头肌最大自主收缩力测试值显著增长(P=0.000),提升幅度显著高于对照组(P=0.008);②试验组受试者的肌肉形态3项指标均显著高于试验前测(P=0.000),而对照组肌肉厚度指标呈显著性下降(P=0.020),羽状角无显著性变化,横截面积显著性提升(P=0.000);③组间对比发现,试验组关于肌肉形态的肌肉厚度(P=0.012)、羽状角(P=0.003)及横截面积(P=0.049)3项指标均显著高于对照组;④上述数据证实,健康成年受试者经过4周的低频脉冲磁场慢性暴露,股四头肌的最大自主收缩力显著提升,同时观察到试验组的肌肉厚度、横截面积及羽状角3项肌肉形态指标的显著增长,对使用该技术作为肌肉改善的运动替代与医疗策略提供了肌组织形态改善的支持依据。

低频磁场治疗对促进脑外伤后患者神经功能恢复的临床研究

目的研究分析低频磁场治疗对促进脑外伤后患者神经功能恢复的临床效果。方法选取2023年3月至2024年1月在浙江省中医院神经外科进行治疗的脑外伤患者90例,随机分为两组。对照组与研究组各45例患者。两组入院后,均进行常规治疗,研究组患者在此基础上给予低频磁场治疗,连续治疗1个月。对比两组患者的临床治疗效果、治疗前后神经功能及血清神经功能因子水平。结果相比对照组,研究组临床治疗总有效率较高,P<0.05。治疗前,两组美国国立卫生院卒中量表(NHISS)评分、格拉斯哥昏迷评分法(GCS)评分相比,P>0.05;治疗后,两组GCS评分均增高,NHISS评分均降低,且研究组两项评分变化较对照组均更为明显,P<0.05。治疗前,两组血清胶质细胞源性神经营养因子(GDNF)、脑源性神经营养因子(BDNF)、髓鞘碱性蛋白(MBP)水平相比,P>0.05;治疗后,两组患者血清GDNF、BDNF水平均增加,血清MBP水平均降低,且研究组三项指标变化较对照组均更为明显,P<0.05。结论低频磁场治疗对脑外伤后患者的疗效显著,可有效调节患者神经功能因子水平,从而促进其神经功能的恢复。

射频联合热风加热对玉米籽粒中黄曲霉毒素B1降解及玉米品质的影响

为研究射频-热风联合处理玉米中的黄曲霉毒素B1(aflatoxin B1,AFB1)降解效果,分析不同初始水分质量分数(19.05%、22.25%、25.55%)、射频加热温度(55、65、75、85℃)和加热持续时间(10、15、20、25 min)对玉米籽粒中AFB1降解效果及玉米品质的影响。结果表明:射频-热风联合处理可有效降解AFB1,在高水分含量下,加热温度和时间一定,初始水分含量越高,AFB1残留量越高;初始水分含量一定,随温度增加和时间延长,AFB1残留量随之减少,且加热持续时间对降解效果的影响大于加热温度;射频-热风联合处理玉米籽粒过程中,对其品质有一定影响,随温度升高和时间延长,与对照组相比,蛋白质、脂肪含量无显著差异(P>0.05),黏度系数显著降低(P<0.05);低场核磁共振分析表明,射频加热过程中水分迁移效果明显,且水分迁移特性与玉米的糊化特性、蛋白质、脂肪含量显著相关(P<0.05)。

低频磁场辅助冻结时间对猪肉理化特性、水分迁移及流变特性的影响

本实验以鲜肉和传统冰箱冻结(-18℃,36 h)为对照,探究低频交变磁场辅助冻结(low-frequency alternating magnetic field assisted freezing,LF-MFF)、-18℃条件下处理不同时间(12、24、36 h和48 h)对猪肉品质的影响,分析不同条件冻结处理后肉样冻结速率、保水性、嫩度、色泽、pH值等理化特性、水分迁移及流变特性的变化。结果表明:与传统冰箱冻结相比,在3 mT低频交变磁场处理条件下,肉样的冻结速率更快,猪肉的品质得到明显改善(P<0.05);所有冻结方式处理中,LF-MFF 36~48 h可提高样品的保水性、色泽和嫩度(P<0.05),维持了更好的理化品质;低场核磁共振(low field nuclear magnetic resonance,LF-NMR)结果显示,与冰箱冻结相比,LF-MFF 36~48 h后显著提高了样品不易流动水的比例,降低了自由水比例(P<0.05);动态流变结果也表明,LF-MFF 36~48 h后样品G’值较高,蛋白质变性程度较低,形成了较好的黏弹性蛋白凝胶。Pearson相关性分析表明,不同冻结处理后猪肉理化特性与水分迁移的变化具有较强的相关性。因此LF-MFF 36~48 h可作为最佳的猪肉冻结条件,可较好地维持猪肉理化特性,降低水分子的迁移率,延缓蛋白变性,改善冻结猪肉的品质。

轨道车辆低频磁场仿真的电磁环境建模分析

在开展轨道交通车辆的低频磁场仿真时,常规方法是对设备箱体添加激励,测试上方对应位点幅值情况,经常会遇到随着测试位点高度的增加,仿真实测误差逐渐增大的情况。文章基于Feko仿真平台,通过建立多方向平面波模型模拟轨道车辆车体内的电磁环境,补充电磁环境参数后发现对于客室车体内各高度的低频磁场仿真误差得到明显修正。

地铁车辆线缆辐射对客室低频磁场影响的仿真

该文针对地铁车辆客室内的低频磁场辐射问题,重点考察车载设备以外的影响因素。虽然通常认为车辆下方的线缆辐射会影响客室内的磁场分布,但这方面的研究相对缺乏。该文借助Feko软件平台,以地铁车辆的设计参数为基础,构建了线槽和线缆布局的模型,并以现场实测的谐波电流值作为模拟分析的激励输入。通过将线缆辐射作为唯一激励源,对线缆产生的磁场进行了仿真分析,并与型式试验实测磁场值进行对比。通过仿真可知,线缆对客室内磁场的贡献远低于型式试验中在相同位置测得的总辐射量。这为处理类似问题提供了一定的参考。

岩石破裂过程中的超低频电磁异常

震前电磁场和大地自电位的异常是重要的地震前兆现象.在零磁空间对超低频段的磁场和自电位的变化进行了岩石破裂的实验研究,细致地揭示出电场、磁场出现异常变化的全过程,对深入认识超低频电磁信号的微观机理具有重要的意义.实验发现,岩石受力后应变、电位和磁场的缓慢变化在空间分布上是首先在近破裂源处出现,继而随裂纹的发展而改变位置;在时间序列上先出现自电位异常,然后是超低频磁场的变化;在异常形态上,超低频电磁信号呈现出早期、中期、晚期3个阶段的明显差异.研究表明,岩石微破裂引起裂隙尖端处的电荷分离. 静电荷在局部区域的积累和运移,导致了自电位的脉冲状变化;而在主破裂阶段,积累电荷的急速运动形成瞬间电流,激发了脉冲式的磁场异常.本文详细介绍了这一综合实验的技术步骤和观测结果,并对地震电磁前兆的微观机理进行了探讨.