Compositional asymmetry between the leaflets of bilayer membranes modifies their phase behavior and is thought to influence other important features such as mechanical properties and protein activity. We address here how phase behavior is affected by passive phospholipid flip-flop, such that the compositional asymmetry is not fixed. We predict transitions from "pre-flip-flop" behavior to a restricted set of phase equilibria that can persist in the presence of passive flip-flop. Surprisingly, such states are not necessarily symmetric. We further account for external symmetry breaking, such as a preferential substrate interaction, and show how this can stabilize strongly asymmetric equilibrium states. Our theory explains several experimental observations of flip-flop-mediated changes in phase behavior and shows how domain formation and compositional asymmetry can be controlled in concert, by manipulating passive flip-flop rates and applying external fields.
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http://dx.doi.org/10.1016/j.bpj.2018.10.003 | DOI Listing |
Materials (Basel)
December 2024
Faculty of Civil Engineering, Cracow University of Technology, Warszawska 24, 31-155 Cracow, Poland.
This paper presents the results of experimental tests and computer simulations on the stiffness of composite aluminium mullions used in unitised façades. The elements analysed were subjected to bending in order to simulate the actual operating conditions of aluminium façades subjected to significant wind pressure or suction loads. The basic mechanical and physical properties of the materials from which the analysed type of aluminium façade is made (Aluminium EN AW-6060 in the T66 temper and polyamide PA66 25GF), the test method, and the results obtained are described.
View Article and Find Full Text PDFACS Nano
January 2025
College of Chemistry and Molecular Sciences, Hubei Key Laboratory of Electrochemical Power Sources, Wuhan University, Wuhan 430072, China.
Chiral plasmonic nanomaterials with fascinating physical and chemical properties show emerging chirality-dependent applications in photonics, catalysis, and sensing. The capability to precisely manipulate the plasmonic chirality in a broad spectral range plays a crucial role in enabling the applications of chiral nanomaterials in diverse and complex scenarios; however, it remains a challenge yet to be addressed. Here we demonstrate a strategy to significantly enhance the tunability of circular dichroism (CD) spectra of chiral nanomaterials by constructing core-shell hybrid metal-semiconductor structures with tailored shells.
View Article and Find Full Text PDFClin Orthop Relat Res
January 2025
School of Biomedical Sciences, The University of Queensland, St. Lucia, Australia.
Background: Adolescent idiopathic scoliosis (AIS) is characterized by an asymmetrical formation of the spine and ribcage. Recent work provides evidence of asymmetrical (right versus left side) paraspinal muscle size, composition, and activation amplitude in adolescents with AIS. Each of these factors influences muscle force generation.
View Article and Find Full Text PDFUnlabelled: Cytoplasmic proteins must recruit to membranes to function in processes such as endocytosis and cell division. Many of these proteins recognize not only the chemical structure of the membrane lipids, but the curvature of the surface, binding more strongly to more highly curved surfaces, or 'curvature sensing'. Curvature sensing by amphipathic helices is known to vary with membrane bending rigidity, but changes to lipid composition can simultaneously alter membrane thickness, spontaneous curvature, and leaflet symmetry, thus far preventing a systematic characterization of lipid composition on such curvature sensing through either experiment or simulation.
View Article and Find Full Text PDFJ Mech Behav Biomed Mater
January 2025
Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Italy.
Endovascular thrombectomy (EVT) aims at restoring blood flow in case of acute ischemic stroke by removing the thrombus occluding a large cerebral artery. During the procedure with stent-retriever, the thrombus is captured within the device, which is then retrieved, subjecting the thrombus to several forces, potentially leading to its fragmentation. In silico studies, along with mechanical characterisation of thrombi, can enhance our understanding of the EVT, helping the development of new devices and interventional strategies.
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