To establish safe and efficient transcranial direct current stimulation (tDCS), it is of particular importance to understand the electrical effects of tDCS in the brain. Since the current density (CD) and electric field (EF) in the brain generated by tDCS depend on various factors including complex head geometries and electrical tissue properties, in this work, we investigated the influence of anisotropic conductivity in the skull and white matter (WM) on tDCS via a 3D anatomically realistic finite element head model. We systematically incorporated various anisotropic conductivity ratios into the skull and WM. The effects of anisotropic tissue conductivity on the CD and EF were subsequently assessed through comparisons to the conventional isotropic solutions. Our results show that the anisotropic skull conductivity significantly affects the CD and EF distribution: there is a significant reduction in the ratio of the target versus non-target total CD and EF on the order of 12-14%. In contrast, the WM anisotropy does not significantly influence the CD and EF on the targeted cortical surface, only on the order of 1-3%. However, the WM anisotropy highly alters the spatial distribution of both the CD and EF inside the brain. This study shows that it is critical to incorporate anisotropic conductivities in planning of tDCS for improved efficacy and safety.
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http://dx.doi.org/10.1088/0031-9155/57/21/6961 | DOI Listing |
Nanoscale
January 2025
Laboratory of Quantum Functional Materials Design and Application, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China.
Two-dimensional materials with a combination of a moderate bandgap, highly anisotropic carrier mobility, and a planar structure are highly desirable for nanoelectronic devices. This study predicts a planar BeP monolayer with hexagonal symmetry that meets the aforementioned desirable criteria using the CALYPSO method and first-principles calculations. Calculations of electronic properties demonstrate that the hexagonal BeP monolayer is an intrinsic semiconductor with a direct band gap of approximately 0.
View Article and Find Full Text PDFComput Methods Programs Biomed
January 2025
Department of Physiology II, Kanazawa Medical University, Uchinada 920-0293, Japan. Electronic address:
Background And Objective: It has been believed that polymorphic ventricular tachycardia (VT) such as torsades de pointes (TdP) seen in patients with long QT syndromes is triggered by creating early afterdepolarization (EAD)-mediated triggered activity (TA). Although the mechanisms creating the TA have been studied intensively, characteristics of the arrhythmogenic (torsadogenic) substrates that link EAD developments to TA formation are still not well understood.
Methods: Computer simulations of excitation propagation in a homogenous two-dimensional ventricular tissue with an anisotropic conduction property were performed to characterize torsadogenic substrates that potentially form TA.
Soft Matter
January 2025
Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
In polymerization-induced phase separation, the impact of polymer-substrate interaction on the dynamics of phase separation for polymer blends is important in determining the final morphology and properties of polymer materials as the surface can act as another driving force for phase separation other than polymerization. We modify the previously-developed polymerizing Cahn-Hilliard (pCH) method by adding a surface potential to model the phase separation behavior of a mixture of two species independently undergoing linear step-growth polymerization in the presence of a surface. In our approach, we explicitly model polydispersity by separately considering different molecular-weight components with their own respective diffusion constants, and with the surface potential preferentially acting on only one species.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Department of Physics, Indian Institute of Science, Bangalore 560012, India.
The quest for anisotropic superconductors has been a long-standing pursuit due to their potential applications in quantum computing. In this regard, experimentally, d-wave and anisotropic s-wave superconducting order parameters are predominantly observed, while p-wave superconductors remain largely elusive. Achieving p-wave superconductivity in topological phases is highly desirable, as it is considered suitable for creating topologically protected qubits.
View Article and Find Full Text PDFRev Sci Instrum
January 2025
Birck Nanotechnology Center and the School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
High heat fluxes in electronic devices must be effectively dissipated to prevent local hotspots, which are critical for long-term device reliability. In particular, advanced semiconductor packaging trends toward thin form factor products increase the need for understanding and improving in-plane conduction heat spreading in anisotropic materials. The 2D laser-based Ångstrom method, an extension of traditional Ångstrom and lock-in thermography techniques, measures in-plane thermal properties of anisotropic sheet-like materials.
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