2,513 research outputs found
Effects of purine nucleotide administration on purine nucleotide metabolism in brains of heroin-dependent rats
Heroin is known to enhance catabolism and inhibit anabolism of purine nucleotides, leading to purine nucleotide deficiencies in rat brains. Here, we determined the effect of exogenous purine nucleotide administration on purine nucleotide metabolism in the brains of heroin-dependent rats. Heroin was administrated in increasing doses for 9 consecutive days to induce addiction, and the biochemical changes associated with heroin and purine nucleotide administration were compared among the treated groups. HPLC was performed to detect the absolute concentrations of purine nucleotides in the rat brain cortices. The enzymatic activities of adenosine deaminase (ADA) and xanthine oxidase (XO) in the treated rat cortices were analyzed, and qRT-PCR was performed to determine the relative expression of ADA, XO, adenine phosphoribosyl transferase (APRT), hypoxanthine-guaninephosphoribosyl transferase (HGPRT), and adenosine kinase (AK). Heroin increased the enzymatic activity of ADA and XO, and up-regulated the transcription of ADA and XO. Alternatively, heroin decreased the transcription of AK, APRT, and HGPRT in the rat cortices. Furthermore, purine nucleotide administration alleviated the effect of heroin on purine nucleotide content, activity of essential purine nucleotide metabolic enzymes, and transcript levels of these genes. Our findings therefore represent a novel, putative approach to the treatment of heroin addiction
Homologous recombination is unlikely to play a major role in influenza B virus evolution
Influenza B viruses cause a significant amount of morbidity and mortality. The occurrence of homologous recombination in influenza viruses is controversial. To determine the extent of homologous recombination in influenza B viruses, recombination analyses of 2,650 sequences representing all eight segments of the influenza B viruses were carried out. Only four sequences were indentified as putative recombinants, which were verified using phylogenetic methods. However, the mosaics detected here were much likely to represent cases of laboratory-generated artificial recombinants. As in other myxoviruses, it is unlikely that homologous recombination plays a major role in influenza B virus evolution
Transmit antenna selection for multiple-input multiple-output spatial modulation systems
The benefits of transmit antenna selection (TAS) invoked for spatial modulation (SM) aided multiple-input multiple-output (MIMO) systems are investigated. Specifically, we commence with a brief review of the existing TAS algorithms and focus on the recently proposed Euclidean distance-based TAS (ED-TAS) schemes due to their high diversity gain. Then, a pair of novel ED-TAS algorithms, termed as the improved QR decomposition (QRD)-based TAS (QRD-TAS) and the error-vector magnitude-based TAS (EVM-TAS) are proposed, which exhibit an attractive system performance at low complexity. Moreover, the proposed ED-TAS algorithms are amalgamated with the low-complexity yet efficient power allocation (PA) technique, termed as TAS-PA, for the sake of further improving the system's performance. Our simulation results show that the proposed TAS-PA algorithms achieve signal-to-noise ratio (SNR) gains of up to 9 dB over the conventional TAS algorithms and up to 6 dB over the TAS-PA algorithm designed for spatial multiplexing systems
7-Nitroquinazolin-4(3H)-one
In the crystal structure of the title compound, C8H5N3O3, intermolecular N—H⋯O hydrogen bonds link molecules into centrosymmetric dimers. These dimers are, in turn, linked though weak intermolecular C—H⋯O and C—H⋯N hydrogen bonds and π–π stacking interactions, with centroid–centroid distances of 3.678 (3) Å, into a three-dimensional network
Visualizing the elongated vortices in -Ga nanostrips
We study the magnetic response of superconducting -Ga via low
temperature scanning tunneling microscopy and spectroscopy. The magnetic vortex
cores rely substantially on the Ga geometry, and exhibit an unexpectedly-large
axial elongation with aspect ratio up to 40 in rectangular Ga nano-strips
(width 100 nm). This is in stark contrast with the isotropic circular
vortex core in a larger round-shaped Ga island. We suggest that the unusual
elongated vortices in Ga nanostrips originate from geometric confinement effect
probably via the strong repulsive interaction between the vortices and Meissner
screening currents at the sample edge. Our finding provides novel conceptual
insights into the geometrical confinement effect on magnetic vortices and forms
the basis for the technological applications of superconductors.Comment: published in Phys. Rev. B as a Rapid Communicatio
catena-Poly[[[aqua(1,10-phenanthroline)zinc(II)]-μ-3,3′-(p-phenylene)diacrylato] hemihydrate]
In the title compound, {[Zn(C12H8O4)(C12H8N2)(H2O)]·0.5H2O}n, each ZnII atom is six-coordinated by two N atoms from one 1,10-phenanthroline (phen), three carboxylate O atoms from two different L ligands [H2
L = 3,3′-(p-phenylene)diacrylic acid] and one water molecule in a distorted octahedral environment. The two L dianions are situated across inversion centres and bridge neighbouring ZnII centres, yielding a chain propagating parallel to [100]. O—H⋯O hydrogen bonds between the coordinated water molecule, the solvent water molecule (half-occupied) and the carboxylate O atoms further stabilize the structure
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