Search results for "kalvot"
showing 10 items of 90 documents
Superconducting size effect in thin films under electric field: Mean-field self-consistent model
2019
We consider effects of an externally applied electrostatic field on superconductivity, self-consistently within a BCS mean field model, for a clean 3D metal thin film. The electrostatic change in superconducting condensation energy scales as $\mu^{-1}$ close to subband edges as a function of the Fermi energy $\mu$, and follows 3D scaling $\mu^{-2}$ away from them. We discuss nonlinearities beyond gate effect, and contrast results to recent experiments.
Negatively Charged Gangliosides Promote Membrane Association of Amphipathic Neurotransmitters
2018
Lipophilic neurotransmitters (NTs) such as dopamine are chemical messengers enabling neurotransmission by adhering onto the extracellular surface of the post-synaptic membrane in a synapse, followed by binding to their receptors. Previous studies have shown that the strength of the NT-membrane association is dependent on the lipid composition of the membrane. Negatively charged lipids such as phosphatidylserine, phosphatidylglycerol, and phosphatidic acid have been indicated to promote NT-membrane binding, however these anionic lipids reside almost exclusively in the intracellular leaflet of the post-synaptic membrane instead of the extracellular leaflet facing the synaptic cleft. Meanwhile…
Ultrafast structural changes within a photosynthetic reaction centre
2021
Nature <London> / Physical science 589, 310 - 314 (2021). doi:10.1038/s41586-020-3000-7
Assembly of Spinach Chloroplast ATP Synthase Rotor Ring Protein-Lipid Complex
2019
Rotor ATPases are large multisubunit membrane protein complexes found in all kingdoms of life. The membrane parts of these ATPases include a ring-like assembly, so-called c-ring, consisting of several subunits c, plugged by a patch of phospholipids. In this report, we use a nature-inspired approach to model the assembly of the spinach (Spinacia oleracea) c14 ring protein-lipid complex, where partially assembled oligomers are pulled toward each other using a biasing potential. The resulting assemblies contain 23 to 26 encapsulated plug lipids, general position of which corresponds well to experimental maps. However, best fit to experimental data is achieved with 15 to 17 lipids inside the c-…
A Perspective : Active Role of Lipids in Neurotransmitter Dynamics
2019
AbstractSynaptic neurotransmission is generally considered as a function of membrane-embedded receptors and ion channels in response to the neurotransmitter (NT) release and binding. This perspective aims to widen the protein-centric view by including another vital component—the synaptic membrane—in the discussion. A vast set of atomistic molecular dynamics simulations and biophysical experiments indicate that NTs are divided into membrane-binding and membrane-nonbinding categories. The binary choice takes place at the water-membrane interface and follows closely the positioning of the receptors’ binding sites in relation to the membrane. Accordingly, when a lipophilic NT is on route to a m…
Lämpösähköisen materiaalin lämmönjohtavuuden määrittäminen matalissa lämpötiloissa käyttäen 3ω-menetelmää
2014
Työssä tutkittiin mittausmenetelmää lämmönjohtavuuden määrittämiseen mata- lissa lämpötiloissa. Mittaukset perustuivat 3ω menetelmään, joka on alunperin ohut- kalvoille kehitetty menetelmä lämmönjohtavuuden mittaukseen. Menetelmässä läm- mitinlangan läpi kulkeva vaihtovirta synnyttää kolminkertaisella taajudella olevan jännitteen, jonka avulla saadaan tietoa kappaleen termisistä ominaisuuksista. Mit- tauksissa kultainen lämmitinlanka höyrystettiin Kapton kalvon päälle ja tämän päälle hyvin ohut alumiinioksidikerros. Mittaukset suoritettiin pulssituubijäähdyttimeen ra- kennetussa näytteenpitimessä. Laitteiston toiminta varmistettiin huoneenlämpötilas- sa borosilikaatti- ja Kapton näytteillä.…
Structure and dynamics of CaO films: A computational study of an effect of external static electric field
2017
Oxide films play a significant role in a wide range of industrial fields, mostly due to the thickness-dependent variation of their properties. Recently, it has been proposed based on the experimental study that carrier transport in CaO films proceeds via strong phonon excitations with a variable signal depending on the film thickness. In this paper, we report a detailed investigation in the frame of the density functional theory of structural and electronic properties of freestanding and Mo(100)-supported CaO films, as well as phonons therein, as functions of the film thickness and intensity of the external static electric field. Our calculations demonstrate that phonon frequencies negligib…
Ultrastiff graphene
2021
Graphene has exceptionally high in-plane strength, which makes it ideal for various nanomechanical applications. At the same time, its exceptionally low out-of-plane stiffness makes it also flimsy and hard to handle, rendering out-of-plane structures unstable and difficult to fabricate. Therefore, from an application point of view, a method to stiffen graphene would be highly beneficial. Here we demonstrate that graphene can be significantly stiffened by using a laser writing technique called optical forging. We fabricate suspended graphene membranes and use optical forging to create stable corrugations. Nanoindentation experiments show that the corrugations increase graphene bending stiffn…
Control of Molecular Orbital Ordering Using a van der Waals Monolayer Ferroelectric
2022
Two-dimensional (2D) ferroelectric materials provide a promising platform for the electrical control of quantum states. In particular, due to their 2D nature, they are suitable for influencing the quantum states of deposited molecules via the proximity effect. Here, we report electrically controllable molecular states in phthalocyanine molecules adsorbed on monolayer ferroelectric material SnTe. In particular, we demonstrate that the strain and ferroelectric order in SnTe creates a transition between two distinct orbital orders in the adsorbed phthalocyanine molecules. By controlling the polarization of the ferroelectric domain using scanning tunneling microscopy (STM), we have successfully…