Numerical computation of distortions in magnetic fields and induced currents in physiological solutions produced by microscope objectives
Numerical computation of distortions in magnetic fields and induced currents in physiological solutions produced by microscope objectives
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DOI：
10.1002/bem.74
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发表时间：
2001-10-01
影响因子：
1.9
通讯作者：
Publicover, NG
中科院分区：
文献类型：
--
作者：
Chatterjee, I;Hassan, N;Publicover, NG
识别失真所产生的常用显微镜物镜和它们的组件在均匀的直流和60赫兹交流磁场是很重要的成像研究，涉及曝光的细胞空间均匀或不均匀的磁场。在这项研究中，DC和60 Hz的AC磁通量密度进行了数值计算的常用显微镜物镜的各种组件的有限元模型的存在下，以及一个完整的目标的模型。还计算了由所施加的时变磁场在包含在培养皿内的生理缓冲液中引起的电流密度的失真。我们表明，磁通密度可以增加到65%，在存在的镍-铬镀层的目标住房和铁磁组件，如螺钉或弹簧的存在下，可以产生的峰值是7%高于未失真的值的磁通密度。此外，物镜相对于磁场的1%的轻微倾斜可能导致磁通量密度与未扰动值的93%偏差。这些结果与先前发表的实验测量结果相关，表明在DC和60 Hz磁场中存在显着的，有时不对称的失真。此外，该研究进一步报告，与不存在目标的值相比，感应电流密度变化高达37%。如果假设细胞在显微镜物镜下暴露于均匀的磁通量密度，则所施加的磁场和感应电流中存在的失真可能会影响细胞功能研究结果的解释。这种均匀磁通密度的假设也可以解释几项通过成像技术检查细胞内钙变化的研究缺乏重现性的原因。(C)2001 Wiley-Liss，Inc.
Identifying distortions produced by commonly employed microscope objectives and their components in uniform DC and 60 Hz AC magnetic fields is important in imaging studies involving exposure of cells to spatially uniform or nonuniform magnetic fields. In this study, DC and 60 Hz AC magnetic flux densities were numerically computed in the presence of finite element models of various components of commonly utilized microscope objectives, as well as a model of a complete objective. Also computed were the distortions in the current density induced by an applied time-varying magnetic field in a physiological buffer contained within a Petri dish. We show that the magnetic flux density could be increased up to 65% in the presence of the nickel-chrome plating of an objective housing and that the presence of ferromagnetic components like a screw or spring could produce peaks that are 7% higher than the undistorted value of magnetic flux density. In addition, a slight tilt of 1% in the objective with respect to the magnetic field could cause a 93% deviation in magnetic flux density from the unperturbed value. These results correlate well with previously published experimental measurements that showed the presence of significant and sometimes asymmetric distortions in both DC and 60 Hz magnetic fields. Moreover, this study further reports that induced current density changed up to 37% compared to values in the absence of the objective. The existence of distortions in applied magnetic fields and induced currents could affect the interpretation of results of cell function studies if it is assumed that the cells are exposed to uniform magnetic flux densities in the presence of a microscope objective. Such assumptions of uniform magnetic flux density could also account for the lack of reproducibility in several studies that examined changes in intracellular calcium by imaging techniques. (C) 2001 Wiley-Liss, Inc.