Search results for "fluidit"

Second sound, superfluid turbulence, and intermittent effects in liquid helium II

2002

Spatial development of multiple-gap states in nonequilibrium superconductors

1985

We have studied the gap instability in a superconductor under tunneling injection at high voltages by probing the spatial distribution of the phonon emission. A high sensitivity was achieved by using the fountain pressure of superfluid helium for detecting the phonons. Spatial structures were observed at gap depressions as small as 2%. From their spatial development we find that the quasiparticles diffuse into regions where their density is higher.

Charge-Induced Deformation of the 4He Solid-Superfluid Interface

1984

The interface between solid and superfluid 4He has revealed unusual dynamic properties. Characteristic of this quantum system are the very high thermal conductivity of the superfluid phase, and an extremely small heat of fusion below temperatures of about 1 K. As a result, equilibrium at the solid-superfluid 4He interface is established quite rapidly, which gives rise, e.g., to melting — crystallization waves [1,2] — similar in appearance to surface waves on a free liquid surface — and to anomalous transmission of sound [3].

Time-domain analysis of electronic spectra in superfluid 4He

2004

Abstract Electronic absorption spectra of impurities in superfluid helium is developed in time domain, using time-dependent density functional theory to describe liquid 4 He and time-dependent perturbation theory to describe the electronic degrees of freedom of the impurity. Angularly isotropic potentials are used to describe the molecule–helium interactions in the ground and excited electronic states. The calculations rationalize experimentally observed phonon side-bands in 4 He droplets and in bulk helium, and allow assignments of spectral features to specific motions of the liquid.

Thermodynamic and Neutron-Diffraction Studies of H2 and D2 Multilayers Physisorbed on Graphite

1991

The evolution of physisorbed films from two-dimensional (2D) to bulk behavior is a topic of high current interest.1 In this context the behavior of the quantum systems H2, HD and D2 is of particular relevance because of the following reasons: 1. Due to the strong influence of the quantum zero-point energy the hydrogen isotopes are highly compressible. This leads to strongly compressed monolayers2,3 before further layer condensation occurs. This property makes these systems significant for the exploration of conditions of multilayer growth. It is generally believed,1,4–6 that the incompatibility between the adsorbate and bulk lattice structures gives rise to lateral strains between the overl…

Inhomogeneous vortex tangles in counterflow superfluid turbulence: flow in convergent channels

2016

Abstract We investigate the evolution equation for the average vortex length per unit volume L of superfluid turbulence in inhomogeneous flows. Inhomogeneities in line density L andincounterflowvelocity V may contribute to vortex diffusion, vortex formation and vortex destruction. We explore two different families of contributions: those arising from asecondorder expansionofthe Vinenequationitself, andthose whichare notrelated to the original Vinen equation but must be stated by adding to it second-order terms obtained from dimensional analysis or other physical arguments.

Membrane fluidity of stressed cells of Oenococcus oeni

2000

International audience; The determination of membrane fluidity in whole cells of Oenococcus oeni was achieved by membrane probe 1,6-diphenyl-1,3,5-hexatriene fluorescence anisotropy measurements. The results demonstrated instantaneous fluidity variations with cells directly stressed during the measure. Heat (42°C) or acid (pH 3.2) shocks decreased the anisotropy values (fluidising effects), whereas an ethanol shock (10% ethanol, v/v) increased the membrane rigidity. The velocities of fluidity variation with non-adapted or adapted cells (incubation in inhibitory growth conditions) were compared. The adaptation of the cells to acid conditions had no effect on the membrane fluidity variation a…

Interaction of an odorant lactone with model phospholipid bilayers and its strong fluidizing action in yeast membrane

2003

International audience; Some odorant lactones are naturally present in fruits or in fermented products; they can also be used as food additives and can be produced by microorganisms at the industrial scale by biotechnological processes. Gamma-decalactone was previously shown to have antimicrobial properties. We determined by infrared spectroscopy measurements that this compound rapidly diffused into model phospholipid bilayers (within 2 min), modifying the general physical state of a dimyristoyl-L-alpha-phosphatidylcholine (DMPC) film. In vivo, the lactone strongly increased membrane fluidity in the model yeast Yarrowia lipolytica, as evaluated by fluorescence anisotropy measurements. This …

Lipid and fatty acid variations inCiona intestinalis ovary after tri-n-butyltin(IV)chloride exposure

2005

Reduction of total lipids (TL) content and significant variations of triglyceride (TG) and phospholipid (PL) fractions were observed as a consequence of exposure of Ciona intestinalis ovaries to tributyltin chloride (TBTCL) solutions. In particular, an evident TG decrease and a PL increase were observed, which probably provoked an increment in membrane fluidity, because of the high concentration of long chain fatty acids and, as a consequence, PL. This could be a cell adaptive standing mechanism towards the pollutants, as observed in Saccharomyces cerevisiae. Also the increase in the content of the polyunsaturated fatty acids (PUFA), important in the synthesis of compounds such as prostagla…

Lipids of the Plant Plasma Membrane

2010

The plasma membrane (PM) is arguably the most diverse membrane of the plant cell. Furthermore, the protein and lipid composition of the PM varies with cell type, developmental stage, and environment. Physical properties of lipids and associate proteins allow the formation of a barrier that is selectively permeable to macromolecules and solutes. As the plasma membrane delineates the interface between the cell and the environment, it is the primary part of signal recognition and transduction into intracellular responses for nutritional uptake/distribution, environmental responses, and developmental signaling. Many essential PM functions are carried out by proteinaceous components. However, PM…