The propagation of an action potential (AP) in a nerve fibre is accompanied by mechanical and thermal effects. In this paper, an attempt is made to build up a mathematical model which couples the AP with a possible pressure wave (PW) in the axoplasm and waves in the nerve fibre wall (longitudinal-LW and transverse-TW) made of a lipid bilayer (biomembrane). A system of differential equations includes the governing equations of single waves with coupling forces between them. The single equations are kept as simple as possible in order to carry out the proof of concept. An assumption based on earlier studies is made that the coupling forces depend on changes (the gradient, time derivative) of the voltage. In addition, it is assumed that the transverse displacement of the biomembrane can be calculated from the gradient of the LW in the biomembrane. The computational simulation is focused to determining the influence of possible coupling forces on the emergence of mechanical waves from the AP. As a result, an ensemble of waves (AP, PW, LW, TW) emerges. The further experiments should verify assumptions about coupling forces.
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http://dx.doi.org/10.1007/s10237-018-1055-2 | DOI Listing |
Biomed Pharmacother
January 2025
Laboratoire d'Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France. Electronic address:
Translational neuroimaging techniques are needed to address the impact of opioid tolerance on brain function and quantitatively monitor the impaired neuropharmacological response to opioids at the CNS level. A multiparametric PET study was conducted in rats. Rats received morphine daily to induce tolerance (15 mg/kg/day for 5 days), followed by 2-day withdrawal.
View Article and Find Full Text PDFMetal oxides are promising catalysts for small molecule hydrogen chemistries, mediated by interfacial proton-coupled electron transfer (PCET) processes. Engineering the mechanism of PCET has been shown to control the selectivity of reduced products, providing an additional route for improving reductive catalysis with metal oxides. In this work, we present kinetic resolution of the rate determining proton-transfer step of PCET to a titanium-doped POV, TiVO(OCH) with 9,10-dihydrophenazine by monitoring the loss of the cationic radical intermediate using stopped-flow analysis.
View Article and Find Full Text PDFSimulating large molecular systems over long timescales requires force fields that are both accurate and efficient. In recent years, E(3) equivariant neural networks have lifted the tension between computational efficiency and accuracy of force fields, but they are still several orders of magnitude more expensive than established molecular mechanics (MM) force fields. Here, we propose Grappa, a machine learning framework to predict MM parameters from the molecular graph, employing a graph attentional neural network and a transformer with symmetry-preserving positional encoding.
View Article and Find Full Text PDFBioinspir Biomim
January 2025
Aerospace Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134, Korea (the Republic of).
This paper describes the tailless control system design of a flapping-wing micro air vehicle in a four-winged configuration, which can provide high control authority to be stable and agile in flight conditions from hovering to maneuvering flights. The tailless control system consists of variable flapping frequency and wing twist modulation. The variable flapping frequency creates rolling moments through differential vertical force from flapping mechanisms that can be independently driven on the left and right sides.
View Article and Find Full Text PDFBMJ Open
January 2025
Department of Plastic and Burn Surgery, Second Affiliated Hospital of Air Force Medical University, Xi'an, Shaanxi, China
Objective: This study aimed to assess the impact of the COVID-19 pandemic on the characteristics and outcomes of patients with burns in a burn centre situated in Northwest China.
Design: A retrospective descriptive study.
Setting: This study was conducted in Tangdu Hospital, a major regional burn centre in Xi'an, Shaanxi Province of China.
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