1,448 research outputs found
The First Spectroscopically Resolved Sub-parsec Orbit of a Supermassive Binary Black Hole
One of the most intriguing scenarios proposed to explain how active galactic
nuclei are triggered involves the existence of a supermassive binary black hole
system in their cores. Here we present an observational evidence for the first
spectroscopically resolved sub-parsec orbit of a such system in the core of
Seyfert galaxy NGC 4151. Using a method similar to those typically applied for
spectroscopic binary stars we obtained radial velocity curves of the
supermassive binary system, from which we calculated orbital elements and made
estimates about the masses of components. Our analysis shows that periodic
variations in the light and radial velocity curves can be accounted for an
eccentric, sub-parsec Keplerian orbit of a 15.9-year period. The flux maximum
in the lightcurve correspond to the approaching phase of a secondary component
towards the observer. According to the obtained results we speculate that the
periodic variations in the observed H{\alpha} line shape and flux are due to
shock waves generated by the supersonic motion of the components through the
surrounding medium. Given the large observational effort needed to reveal this
spectroscopically resolved binary orbital motion we suggest that many such
systems may exist in similar objects even if they are hard to find. Detecting
more of them will provide us with insight into black hole mass growth process.Comment: 29 pages, 10 figures, published in ApJ, 759, 11
Aportació a l'estudi de la micoflora alpina dels Pirineus (1ª part)
Primer treball dels autors estudiant diferents espècies alpines recol.lectades als
Pirineus; s'inclouen descripcions macro i microscòpiques i fotografies.Contribution to the fungal alpine flore of the Pyrenaean range (Part 1). The
authors report some interesting alpine species collected in the Pyrenees. Descriptions and
photographs are provided
Aportació a l'estudi de la micoflora alpina dels Pirineus (1ª part)
Primer treball dels autors estudiant diferents espècies alpines recol.lectades als
Pirineus; s'inclouen descripcions macro i microscòpiques i fotografies.Contribution to the fungal alpine flore of the Pyrenaean range (Part 1). The
authors report some interesting alpine species collected in the Pyrenees. Descriptions and
photographs are provided
Dynamics of Electron Transport in Cytochrome P450 Systems Studied at Sub-Zero Temperature
Experimentation in fluid mixed solvents (1 : 1 v/v phosphate
buffer ethylene glycol) at sub-zero temperatures has permitted us
to record the two univalent reductions of the bacterial cytochrome
P450 by the natural electron donor putidaredoxin, without recycling
or alternative pathway reactions. Dynamic evidence shows the formation of putidaredoxincytochrome complexes prior to electron
transfer. The complex formation is rate limiting in the first reduction
and in our experimental conditions. The kinetics of binding
between the two oxidized proteins has also been recorded in the
same medium under various conditions of concentration, temperature
and ionic strength. At very low ionic strength, the rate is
limited by electrostatic repulsion between the two negatively charge
proteins; above I = 0.03 this effect appears negligible and the affinity
seems to be governed by hydrophobic interaction free energy
Poly[[μ2-(1Z,N′E)-2-(1,3-benzothiazol-2-ylsulfanyl)-N′-(2-oxidobenzylidene-κ2 O:O)acetohydrazidato-κ2 O,N′](pyridine-κN)copper(II)]
In the title compound, [Cu(C16H11N3O2S2)(C5H5N)]n, the CuII atom displays a square-pyramidal CuN2O3 coordination geometry with strong elongation in the vertex direction. The hydrazone molecule is coordinated to the CuII atom in a tridentate manner in the enolic form, creating five- and six-membered chelate metallarings. The pyridine molecule completes the square-planar base of the copper coordination environment. The crystal structure displays zigzag polymeric Cu—O—Cu chains along [001]. Several weak π–π interactions between benzothiazole rings were found in the same direction [centroid–centroid distances = 3.7484 (16), 3.7483 (16), 3.6731 (17) and 3.7649 (17) Å]
[1-(2-Oxidobenzylidene)-4-phenylthiosemicarbazidato-κ3 O,N 1,S](pyridine-κN)copper(II)
In the structure of the title compound, [Cu(C14H11N3OS)(C5H5N)], the CuII atom exhibits a slightly distorted square-planar CuN2OS coordination polyhedron consisting of a phenyl O, an azomethine N and a thioamide S atom from the tridentate thiosemicarbazonate dianion, and the N atom of a pyridine molecule. The thiosemicarbazonate ligand exists in the thiol tautomeric form as an E isomer. Rotational disorder of the pyridine and phenyl rings in a 1:1 ratio of the respective components is observed. An extensive network of weak N—H⋯S, C—H⋯O, C—H⋯N and C—H⋯S hydrogen-bonding interactions consolidates the structure
3 Effects of Antenatal Alcoholization on Brain Cortex Neurons Postnatal Development in Rats
Ethanol consumption, pregnancy, off spring, frontal cortex, neuronsТhe aim of the paper was to estimate histologically the consequences of alcohol consumption by rats during pregnancy on the brain co rte x neurons development in their offspring. Female Wistar rats consumed a 15% solution of ethanol as a single source of drinking (4.64±2.19 g/kg/day) throughout pregnancy, control rats received aquivolume amount of water. The offspring were decapitated on the 2-, 5-, 10-, 20-, 45-, and 90th day after birth and samples of frontal brain cortex were prepared for microscopy histology, histochemistry and electron microscopy. Results: Antenatal alcohol exposure in rats increased, and then reduced the brain cortex thickness, the decrease being noted in the relative amount of brain cortex neurons and the increase in the number of their pathological forms in all time periods of the examination. Electron microscopy showed a significant reduction in the number of mitochondria per um2 of cytoplasm and the total length of their cristae, reduction of the rough endoplasmic reticulum canal length and their clearance expansion, decrease in the bind ribosomes and increase in the free ribosomes number, expansion of the Golgi apparatus cisternae, increase in the lysosome number and size in the cytoplasm of neurons. The histochemical examination revealed the inhibition of NADH-, NADPhH, glucose-6-phosphate dehydrogenase and succinate dehydrogenases as well as activation of lactate dehydrogenase and acid phosphatase. Antenatal alcoholization led to the decrease in the expression of synaptophisin (marker of synaptogenesis) and retarded the maturation of neurons in the frontal cortex, which resulted in the increase in the expression of double cortin, and decrease in the expression of neuronal nuclear antigen. Conclusion: Alcohol consumption by rats during pregnancy induces deep and long-term histological, histochemical, immune histochemical and electron microscopy changes in the brain cortex neurons in postnatal ontogenesis in rat offspring, including early swelling and postpone shrinkage and cessation of growth of brain cortex neurons
The development of the internal pyramidal layer neurons of the brain parietal cortex in rats after prenatal alcohol exposure
The aim of the paper was to estimate histologically the effect of alcohol consumption by rats during pregnancy on the parietal cortex neurons development in their offspring. Female Wistar rats consumed a 15% solution of ethanol as a single source of drinking (3.64 ± 2.2 g/kg/day) throughout pregnancy, control rats received equivolume amounts of water. The offspring were decapitated on the 2-, 5-, 10-, 20-, 45-, and 90th days after birth and the samples of the brain parietal cortex were prepared for histological examination in combination with morphometry to examine the 5th layer inner pyramidal neurons.
Results: Antenatal alcohol exposure in rats increased (on the 2nd and 5th postnatal days), and then reduced (on the 10th and 90th days) the parietal cortex thickness, decreased the amount of parietal cortex inner pyramidal neurons and increased the number of their pathological forms at all time intervals of the examination. Starting from the 20th postnatal day the shrinkage and cessation of the growth of inner pyramidal neurons was observed.
Conclusion: Alcohol consumption by rats during pregnancy induces deep and long-term histological changes in the parietal cortex neurons in postnatal ontogenesis in rat offspring including early swelling and postpone shrinkage and the cessation of growth of the brain cortex inner pyramidal neurons
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