Search results for "POLARIZATION"
showing 10 items of 1884 documents
About the dynamics of strongly coupled surface plasmon polaritons and Sulforhodamine 101
2014
We investigate the dynamics of strongly coupled surface plasmon polaritons (SPP) and molecular excitations (ME) of Sulforhodamine 101 dye. The SPPs are excited by prism coupling technique on a thin silver film with dye molecules embedded in a polymer layer on top of it. Rabi splittings with energies of 135 and 97 meV are observed in the recorded dispersion relations. Both coupled oscillator model and transfer matrix method are used to fit the experimental results. In addition to the common reflectance measurements, polarization resolved detection of scattered signal from the molecular side is also utilized. Simultaneous detection of the scattered polaritons and molecular fluorescence reveal…
A star product on the spherical harmonics
1996
We explicitly define a star product on the spherical harmonics using the Moyal star product on ℝ6, and a polarization equation allowing its restriction on S2.
Relationship between ethanol tolerance, lipid composition and plasma membrane fluidity inSaccharomyces cerevisiaeandKloeckera apiculata
1994
The lipid composition of a strain of each of two yeasts, Saccharomyces csrevisiae and Kloeckera apiculata, with different ethanol tolerances, was determined for cells grown with or without added ethanol. An increase in the proportion of ergosterol, unsaturated fatty acid levels and the maintenance of phospholipid biosynthesis seemed to be responsible for ethanol tolerance. The association of ethanol tolerance of yeast cells with plasma membrane fluidity, measured by fluorescence anisotropy, is discussed. We propose that an increase in plasma membrane fluidity may be correlated with a decrease in the sterol: phospholipid and sterol: protein ratios and an increase in unsaturation index.
Membrane potential-dependent binding of polysialic acid to lipid monolayers and bilayers
2013
AbstractPolysialic acids are linear polysaccharides composed of sialic acid monomers. These polyanionic chains are usually membrane-bound, and are expressed on the surfaces of neural, tumor and neuroinvasive bacterial cells. We used toluidine blue spectroscopy, the Langmuir monolayer technique and fluorescence spectroscopy to study the effects of membrane surface potential and transmembrane potential on the binding of polysialic acids to lipid bilayers and monolayers. Polysialic acid free in solution was added to the bathing solution to assess the metachromatic shift in the absorption spectra of toluidine blue, the temperature dependence of the fluorescence anisotropy of DPH in liposomes, t…
Evaluation of Arsenate- and Vanadate-Associated Changes of Electrical Membrane Potential and Phosphate Transport inLemna gibbaG1
1989
Interference of arsenate and vanadate with phosphate uptake in Lemna gibba L. was studied by measuring voltage changes and (32P)phosphate uptake. Arsenate proved to be competitive with the highand low-affinity phosphate uptake system. It induced transient membrane potential changes of up to 120 mV which were similar to those induced by phosphate and indicated a cotransport mechanism with at least 2H+/H2As04. The amplitude of the transient arsenate-induced membrane depolarization was strongly influenced by phosphate starvation. A permanent membrane depolarization to the diffusion potential was achieved within 2 to 6 h in P-starved plants. Thus, arsenate is indeed a strongly competitive physi…
Nonlinear conductance and heterogeneity of voltage-gated ion channels allow defining electrical surface domains in cell membranes
2015
Abstract The membrane potential of a cell measured by typical electrophysiological methods is only an average magnitude and experimental techniques allowing a more detailed mapping of the cell surface have shown the existence of spatial domains with locally different electric potentials and currents. Electrical potentials in non-neural cells are regulated by the nonlinear conductance of membrane ion channels. Voltage-gated potassium channels participate in cell hyperpolarization/depolarization processes and control the electrical signals over the cell surface, constituting good candidates to study basic biological questions on a more simplified scale than the complex cell membrane. These ch…
Membrane potential bistability in nonexcitable cells as described by inward and outward voltage-gated ion channels.
2014
The membrane potential of nonexcitable cells, defined as the electrical potential difference between the cell cytoplasm and the extracellular environment when the current is zero, is controlled by the individual electrical conductance of different ion channels. In particular, inward- and outward-rectifying voltage-gated channels are crucial for cell hyperpolarization/depolarization processes, being amenable to direct physical study. High (in absolute value) negative membrane potentials are characteristic of terminally differentiated cells, while low membrane potentials are found in relatively depolarized, more plastic cells (e.g., stem, embryonic, and cancer cells). We study theoretically t…
Two cases of adynamia episodica hereditaria: In vitro investigation of muscle cell membrane and contraction parameters
1983
Membrane potentials, current-voltage relationships, and contractile parameters were studied in intact muscle cell bundles obtained from two patients with adynamia episodica hereditaria. In a normal extracellular medium, the cell membranes had resting potentials of about -80 mV and their current-voltage relationships were not significantly different from control curves. In contrast to normal muscles the afflicted cells were paralyzed in a medium having 6-10 mmol/liter potassium. The mechanisms of paralysis in the two specimens were different from each other. Many fibers from one patient were spontaneously active even in normal solution. In high potassium solution spontaneous activity was inc…
Discoordinate regulation of different K channels in cultured rat skeletal muscle by nerve growth factor
1999
We investigated the effects of nerve growth factor (NGF) on expression of K+ channels in cultured skeletal muscle. The channels studied were (1) charybdotoxin (ChTx)-sensitive channels by using a polyclonal antibody raised in rabbits against ChTx, (2) Kv1.5 voltage-sensitive channels, and (3) apamin-sensitive (afterhyperpolarization) channels. Crude homogenates were prepared from cultures made from limb muscles of 1-2-day-old rat pups for identification of ChTx-sensitive and Kv1.5 channels by Western blotting techniques. Apamin-sensitive K+ channels were studied by measurement of specific [125I]-apamin binding by whole cell preparations. ChTx-sensitive channels display a fusion-related incr…
COMPARATIVE STUDY ON THE ELECTROPHYSIOLOGICAL EFFECTS OF MONENSIN ON ATRIAL AND VENTRICULAR MUSCLE PREPARATIONS OF GUINEA-PIG HEART
1995
The effects of monensin (10 µmol/L) alone and in presence of verapamil (3 µmol/L) or ouabuin (1 µmol/L) or glibenclamide (10 µmol/L) or BaCl2 separately were studied on the electrophysiological properties represented by force of contraction, duration of action potential, and membrane resting potential of isolated atrial and ventricular muscle of guinea –pig heart. Monensin induced a transient increase in the force of contraction of atrial and ventricular muscles. It caused a decrease in action potential duration of papillary muscle, this effect was reversed by glibenclamide. Monensin increased the action potential duration of atrial muscle in absence or presence of glibenclamide. In presenc…