Standard volume conductor models of neural electrical stimulation assume that the electrical properties of the tissue are well described by a conductivity that is smooth and homogeneous at a microscopic scale. However, neural tissue is composed of tightly packed cells whose membranes have markedly different electrical properties to either the intra- or extracellular space. Consequently, the electrical properties of tissue are highly heterogeneous at the microscopic scale: a fact not accounted for in standard volume conductor models. Here we apply a recently developed framework for volume conductor models that accounts for the cellular composition of tissue. We consider the case of a point source electrode in tissue comprised of neural fibers crossing each other equally in all directions. We derive the tissue admittivity (that replaces the standard tissue conductivity) from single cell properties, and then calculate the extracellular potential. Our findings indicate that the cellular composition of tissue affects the spatiotemporal profile of the extracellular potential. In particular, the full solution asymptotically approaches a near-field limit close to the electrode and a far-field limit far from the electrode. The near-field and far-field approximations are solutions to standard volume conductor models, but differ from each other by nearly an order or magnitude. Consequently the full solution is expected to provide a more accurate estimate of electrical potentials over the full range of electrode-neurite separations.
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http://dx.doi.org/10.1109/EMBC.2014.6944711 | DOI Listing |
Molecules
November 2024
School of Chemistry and Chemical Engineering, Inner Mongolia University of Science and Technology, Baotou 014010, China.
Double perovskite oxides with mixed ionic and electronic conductors (MIECs) have been widely investigated as cathode materials for solid oxide fuel cells (SOFCs). Classical Fe-based double perovskites, due to their inherent low electronic and oxygen ionic conductivity, usually exhibit poor electrocatalytic activity. The existence of various valence states of B-site ions modifies the material's catalytic activity, indicating the possibility of the partial substitution of Fe by higher-valence ions.
View Article and Find Full Text PDFJ Appl Physiol (1985)
January 2025
Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States.
This review follows two previous papers [Farina et al. 96: 1486-1495, 2004; Farina et al. 117: 1215-1230, 2014] in which we reflected on the use of surface electromyography (EMG) in the study of the neural control of movement.
View Article and Find Full Text PDFNanotechnology
November 2024
State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, People's Republic of China.
Tribological printing is emerging as a promising technique for micro/nano manufacturing. A significant challenge is enhancing efficiency and minimizing the need for thousands of sliding cycles to create nano- or microstructures (2018). This study presents a rapid approach for forming Cu microwires on Si wafers through a friction method during the evaporation of an ethanol-based lubricant containing Cu nanoparticles.
View Article and Find Full Text PDFInorg Chem
December 2024
State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China.
Lithium metal anodes generally suffer from uncontrolled dendrite growth and large volume change, while traditional skeletons such as LiIn and LiSn are too heavy and discontinuous to offer highly efficient structural supportability for composite Li anodes. In this work, lightweight and stable fiber-clustered skeletons, which are composed of LiB fibers and jointed LiSi nanoparticles, can be obtained by smelting SiB powder and Li ingots. In addition to serving as both ionic and electronic conductors for composite Li anodes, the stable skeletons reduced volumetric fluctuation by offering uniform, heterogeneous, and continuous architectures while suppressing lithium dendrites with low nucleation overpotential and diffusion energy barrier.
View Article and Find Full Text PDFProtoplasma
November 2024
Mercy University, Dobbs Ferry, NY, 10522, USA.
I present here a rebuttal to an article in this volume wherein Kingsland and Taiz (2024) cast aspersions about an article I have written concerning Sir Jagadis Chandra Bose (Minorsky PV, in Plant Signal Behav 16:1818030, 2021) a brilliant Bengali scientist who was a pioneer not only in physics (microwaves and semi-conductors), but also in elucidating the electrophysiological responses of plants to environmental stimuli. The charge of racism that I have levelled at Bose's most powerful and well-connected botanical adversary in the 1920s, Daniel T. MacDougal, is irrefutable: MacDougal was a racist, his racism extended to South Asians, and he used racist epithets in referring to Bose.
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