Ferrimagnetic Particles in the Lung Part 1: The Magnetizing Process
Ferrimagnetic Particles in the Lung Part 1: The Magnetizing Process
复制标题
肺中的亚铁磁性颗粒第 1 部分：磁化过程
DOI：
10.1109/tbme.1984.325265
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发表时间：
1984
影响因子：
4.6
通讯作者：
I. Nemoto
中科院分区：
文献类型：
--
作者：
D. Cohen;I. Nemoto
当外部磁场施加到肺部时，肺部中的亚铁磁性颗粒就会发生磁化过程；粒子都被磁化并旋转以与所施加的场对齐。此处的目的是巩固此过程之前和新的测量结果（针对人肺中的 Fe3O4 颗粒），并解释测量结果。测量的具体量是 Bn，即去除外加磁场后粒子在胸部产生的剩余磁场。 Bn 被测量为三个变量的函数。前两个是施加磁场的强度和持续时间，分别产生剩磁曲线和粘度曲线；这些都是针对最初未磁化和最初磁化的颗粒进行测量的。这些曲线通过由单域和多域粒子组成的简单物理模型进行定性解释；它们驻留在粘性流体中并经历生理脉冲（松弛），这在磁化过程中反对对齐。第三个变量是呼吸状态； Bn 是在磁化或测量期间将正常呼吸切换为呼气并屏住时测量的。通过考虑肺泡壁来解释该开关对 Bn 的影响；强制呼气被认为会“压碎”肺泡壁，从而重新排列肺泡中包含的颗粒。
The magnetization process of ferrimagnetic particles in the lung takes place when an external magnetic field is applied to the lung; the particles both become magnetized and rotate toward alignment with the applied field. The purpose here is to consolidate previous and new measurements of this process, for Fe3O4 particles in the human lung, and to interpret the measurements. The particular quantity measured was Bn, the remanent magnetic field at the chest produced by the particles after removal of the applied field. Bn was measured as a function of three variables. The first two are the strength and duration of the applied field, yielding the remanent magnetization curve and the viscosity curve respectively; these were measured both for particles initially unmagnetized and initialiy magnetized. The curves are qualitatively explained by a simple physics model consisting of single-domain and multidomain particles; these reside in a viscous fluid and experience physiological impulses (relaxation) which oppose the alignment during magnetization. The third variable is the state of breathing; Bn was measured when normal breathing was switched to exhale-and-hold during either magnetization or measurement. The effects on Bn of this switch are explained by considering the alveolar walls; forced exhalation is assumed to "crumple" the walls, thereby realigning the particles contained in the alveoli.