Özarslan Evren, Yolcu Cem, Herberthson Magnus, Westin Carl-Fredrik, Knutsson Hans
Department of Biomedical Engineering, Linköping University, Linköping, Sweden.
Division of Mathematics and Applied Mathematics, Department of Mathematics, Linköping University, Linköping, Sweden.
Front Phys. 2017;5. doi: 10.3389/fphy.2017.00068. Epub 2017 Dec 19.
The signature of diffusive motion on the NMR signal has been exploited to characterize the mesoscopic structure of specimens in numerous applications. For compartmentalized specimens comprising isolated subdomains, a representation of individual pores is necessary for describing restricted diffusion within them. When gradient waveforms with long pulse durations are employed, a quadratic potential profile is identified as an effective energy landscape for restricted diffusion. The dependence of the stochastic effective force on the center-of-mass position is indeed found to be approximately linear (Hookean) for restricted diffusion even when the walls are sticky. We outline the theoretical basis and practical advantages of our picture involving effective potentials.
在众多应用中，核磁共振信号上扩散运动的特征已被用于表征样本的介观结构。对于由孤立子域组成的分隔样本，描述其中受限扩散需要对单个孔隙进行表征。当采用具有长脉冲持续时间的梯度波形时，二次势分布被视为受限扩散的有效能量图景。实际上，即使壁面具有粘性，对于受限扩散，随机有效力对质心位置的依赖性也被发现近似呈线性（胡克定律）。我们概述了涉及有效势的图景的理论基础和实际优势。
