Na
+
/K
+
-pump is an electrogenic transmembrane ATPase located in the outer plasma membrane of cells. The Na
+
/K
+
-ATPase pumps 3 sodium ions out of cells while pumping 2 potassium ions into ...cells. Both cations move against their concentration gradients. This enzyme’s electrogenic nature means that it has a chronic role in stabilizing the resting membrane potential of the cell, in regulating the cell volume and in the signal transduction of the cell. This review will mainly consider the role of the Na
+
/K
+
-pump in neurons, with an emphasis on its role in modulating neurotransmitter receptor. Most of the literature on the modulation of neurotransmitter receptors refers to the situation in the mammalian nervous system, but the position is likely to be similar in most, if not all, invertebrate nervous systems.
This paper presents a new model of dispersion of components in transport processes. It is suggested that the flow velocity may be specified by a Gauss function with relative dispersion of flow ...velocity
β
=
σ
v
/
v
; the overall dispersion of inert component (in porous as well as in homogeneous medium) may be calculated from the equation
σ
=
(
2
D
t
/
τ
2
+
(
β
v
t
)
2
)
0.5
, where
D is the diffusion coefficient,
t is time,
τ is tortuosity, and
v is flow velocity. The most common range of variability of relative dispersion of flow velocity in natural soils is 8–32%. The model is well applicable to column and field experiments.
The heat exchange process of moist sodium carboxymethyl cellulose is studied. The method for determining the thermal conductivity coefficient of a moist disperse material is developed. The ...thermophysical properties of sodium carboxymethyl cellulose are determined. The influence of moisture content and density of the material on its thermal conductivity coefficient is studied. An empirical equation is derived by processing the experimental data to calculate the thermal conductivity coefficient of sodium carboxymethyl cellulose at different densities of the moist material.
Using electrophysiology, the effect of nicotinic acetylcholine receptor (nAChR) ligands on acetylcholine-induced depolarization in the neurons of
Helix lucorum
snail was studied. It was found that ...the α-conotoxin PnIA R9, L10, a selective antagonist of α7 nAChR, and α-cobratoxin (antagonist of α7 and muscle-type nAChR) suppressed neuronal depolarization. Fluorescence microscopy showed staining of the neurons with fluorescently labeled α-bungarotoxin; this staining was reduced by pretreatment with α-cobratoxin. Induced depolarization was also suppressed by α-conotoxin RgIA, a selective inhibitor of α9 nAChR. In contrast to
Lymnaea stagnalis
nAChR, which are weakly sensitive to neurotoxin II and α-conotoxin GI, antagonists of muscle-type nAChR,
H. lucorum
receptors were most effectively inhibited by these antagonists. The results obtained, as well as the previously found sensitivity of the receptors studied in this work to muscarinic receptor ligands, indicate an unusual atypical pharmacological profile of
H. lucorum
nAChR.
The simplest polycyclic aromatic hydrocarbon (PAH) carrying a five‐membered ring—9H‐fluorene (C13H10)—is produced isomer‐specifically in the gas phase by reacting benzyl (C7H7⋅) with phenyl (C6H5⋅) ...radicals in a pyrolytic reactor coupled with single photon ionization mass spectrometry. The unconventional mechanism of reaction is supported by theoretical calculations, which first produces diphenylmethane and unexpected 1‐(6‐methylenecyclohexa‐2,4‐dienyl)benzene intermediates (C13H12) accessed via addition of the phenyl radical to the ortho position of the benzyl radical. These findings offer convincing evidence for molecular mass growth processes defying conventional wisdom that radical‐radical reactions are initiated through recombination at their radical centers. The structure of 9H‐fluorene acts as a molecular building block for complex curved nanostructures like fullerenes and nanobowls providing fundamental insights into the hydrocarbon evolution in high temperature settings.
Gas‐phase synthesis of 9H‐fluorene (C13H10)—the simplest polycyclic aromatic system carrying a five‐membered ring—along with diphenylmethane (C13H12) via unconventional reaction dynamics of the benzyl (C7H7⋅) with the phenyl (C6H5⋅) radical is reported.
This paper presents the results of the 4th International Comparison of in vitro electron paramagnetic resonance dosimetry with tooth enamel, where the performance parameters of tooth enamel dosimetry ...methods were compared among sixteen laboratories from all over the world. The participating laboratories were asked to determine a calibration curve with a set of tooth enamel powder samples provided by the organizers. Nine molar teeth extracted following medical indication from German donors and collected between 1997 and 2007 were prepared and irradiated at the Helmholtz Zentrum Muenchen. Five out of six samples were irradiated at 0.1, 0.2, 0.5, 1.0 and 1.5 Gy air kerma; and one unirradiated sample was kept as control. The doses delivered to the individual samples were unknown to the participants, who were asked to measure each sample nine times, and to report the EPR signal response, the mass of aliquots measured, and the parameters of EPR signal acquisition and signal evaluation. Critical dose and detection limit were calculated by the organizers on the basis of the calibration-curve parameters obtained at every laboratory. For calibration curves obtained by measuring every calibration sample three times, the mean value of the detection limit was 205 mGy, ranging from 56 to 649 mGy. The participants were also invited to provide the signal response and the nominal dose of their current dose calibration curve (wherever available), the critical dose and detection limit of which were also calculated by the organizers.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellar medium and in meteorites such as Murchison and Allende and signify the missing link between resonantly stabilized free ...radicals and carbonaceous nanoparticles (soot particles, interstellar grains). However, the predicted lifetime of interstellar PAHs of some 10
years imply that PAHs should not exist in extraterrestrial environments suggesting that key mechanisms of their formation are elusive. Exploiting a microchemical reactor and coupling these data with computational fluid dynamics (CFD) simulations and kinetic modeling, we reveal through an isomer selective product detection that the reaction of the resonantly stabilized benzyl and the propargyl radicals synthesizes the simplest representative of PAHs - the 10π Hückel aromatic naphthalene (C
H
) molecule -
the novel Propargyl Addition-BenzAnnulation (PABA) mechanism. The gas-phase preparation of naphthalene affords a versatile concept of the reaction of combustion and astronomically abundant propargyl radicals with aromatic radicals carrying the radical center at the methylene moiety as a previously passed over source of aromatics in high temperature environments thus bringing us closer to an understanding of the aromatic universe we live in.
Drift chamber for the CMD-3 detector Grancagnolo, F.; Fiore, G.; Ignatov, F.V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2010, Letnik:
623, Številka:
1
Journal Article
Recenzirano
The construction, digitizing electronics and results of test with cosmic rays of cylindrical drift chamber for CMD-3 detector are described. To uniformly fill the sensitive volume small hexagonal ...cells were chosen. The coordinate along the wire is measured by charge division technique. A resolution in the R–ϕ-plane of better than 110μm and about 3mm along the wire as well as a dE/dx resolution of about 12% were obtained in cosmic test runs.
The hydrography of the Laptev Sea is significantly influenced by river water and sea-ice processes, which are highly variable over the annual cycle. Despite of an estuarine structure the inner and ...outer shelf regions are decoupled at times as documented by the stability of a warm intermediate layer formed during summer below the Lena River plume. We demonstrate that a remnant of this warm layer is preserved below the fast ice until the end of winter, while only slightly farther to the north, offshore of the landfast ice in the polynya region, the pycnocline is eroded and no signature of this layer is found. The warm intermediate layer (WIL) formed during summer can be used as tracer for Laptev Sea shelf waters throughout the winter. Thereby, residence times of southern Laptev Sea waters can be estimated to be at least from summer to the end of winter/spring of the following year.
The actions of the nootropes noopept and piracetam on depression of the acetylcholine-induced current in a cellular analog of habituation were studied. Mathematical modeling of experimental curves ...and their analysis using previously obtained results on the effects of inhibitors of different protein kinases and protein phosphatases on acquisition of depression of the acetylcholine-induced current in a cellular analog of habituation clarified the intracellular processes and targets on which these agents act.
PDF
