2,413 research outputs found

    The first non-mammalian CXCR5 in a teleost fish: molecular cloning and expression analysis in grass carp (Ctenopharyngodon idella)

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    <p>Abstract</p> <p>Background</p> <p>Chemokines, a group of small and structurally related proteins, mediate chemotaxis of various cell types via chemokine receptors. In mammals, seven different CXC chemokine receptors denoted as CXCR1 to CXCR7 have been reported. However, the chemokine receptor CXCR5 has not been reported in other vertebrates.</p> <p>Results</p> <p>In the present study, the genomic sequence of CXCR5 was isolated from the grass carp <it>Ctenopharyngodon idella</it>. The cDNA sequence of grass carp CXCR5 (gcCXCR5) consists of 1518 bp with a 43 bp 5' untranslated region (UTR) and a 332 bp 3' UTR, with an open reading frame of 1143 bp encoding 381 amino acids which are predicted to have seven transmembrane helices. The characteristic residues (DRYLAIVHA) and conserved cysteine residues are located in the extracellular regions and in the third to seventh transmembrane domains. The deduced amino acid sequence shows 37.6-66.6% identities with CXCR5 of mammals, avian and other fish species. The grass carp gene consists of two exons, with one intervening intron, spaced over 2081 bp of genomic sequence. Phylogenetic analysis clearly demonstrated that the gcCXCR5 is clustered with those in other teleost fish and then in chicken and mammals. Real-time PCR analysis showed that gcCXCR5 was expressed in all tested organs/tissues and its expression level was the highest in trunk kidney, followed by in the spleen. The expression of gcCXCR5 was significantly modulated by immunostimulants such as peptidoglycan (PGN), lipopolysaccharide (LPS), polyinosinic-polycytidylic acid sodium salt (Poly I:C) and phytohaemagglutinin (PHA).</p> <p>Conclusion</p> <p>The cDNA and genomic sequences of CXCR5 have been successfully characterized in a teleost fish, the grass carp. The CXCR5 has in general a constitutive expression in organs/tissues examined, whereas its expression was significantly up-regulated in immune organs and down-regulated in brain, indicating its potential role in immune response and central nervous system.</p

    Investigation of the effect of initial states of medium-Mn steel on deformation behaviour under hot stamping conditions

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    Medium-Mn (MMn) steels have received much research attention recently because their low austenitisation temperature enables low-temperature hot stamping (LTHS). However, the effect of the initial state of the material on the hot stamping performance is still unknown. In this study, the effect of different initial states on the deformation behaviour of a typical MMn steel during uniaxial tensile testing under LTHS conditions (deformation at 500–600 °C under strain rates of 0.01–1 s−1) are investigated using a Gleeble 3800 materials simulator; the final mechanical properties after austenitising and quenching are also examined. The microstructure of each material state before and after the LTHS heating cycle is characterised using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Of the three states investigated the hot rolled and annealed (HRA) state shows the best hot deformation performance represented by larger strain hardening exponent and higher total elongation, followed by the cold-rolled (CR) state, with the cold-rolled and annealed (CRA) state exhibiting the worst performance. The final mechanical properties, however, are very similar among the three states. In addition, the yield point phenomenon is found during hot deformation in both the CR and CRA states, and absent in the HRA state. The hot deformation behaviour has been discussed in terms of differences in microstructural properties, namely the grain size and its degree of heterogeneity

    How early can myocardial iron overload occur in Beta thalassemia major?

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    BACKGROUND: Myocardial siderosis is the most common cause of death in patients with beta thalassemia major(TM). This study aimed at investigating the occurrence, prevalence and severity of cardiac iron overload in a young Chinese population with beta TM. METHODS AND RESULTS: We analyzed T2* cardiac magnetic resonance (CMR), left ventricular ejection fraction (LVEF) and serum ferritin (SF) in 201 beta TM patients. The median age was 9 years old. Patients received an average of 13 units of blood per year. The median SF level was 4536 ng/ml and 165 patients (82.1%) had SF>2500 ng/ml. Myocardial iron overload was detected in 68 patients (33.8%) and severe myocardial iron overload was detected in 26 patients (12.6%). Twenty-two patients ≤10 years old had myocardial iron overload, three of whom were only 6 years old. No myocardial iron overload was detected under the age of 6 years. Median LVEF was 64% (measured by CMR in 175 patients). Five of 6 patients with a LVEF<56% and 8 of 10 patients with cardiac disease had myocardial iron overload. CONCLUSIONS: The TM patients under follow-up at this regional centre in China patients are younger than other reported cohorts, more poorly-chelated, and have a high burden of iron overload. Myocardial siderosis occurred in patients younger than previously reported, and was strongly associated with impaired LVEF and cardiac disease. For such poorly-chelated TM patients, our data shows that the first assessment of cardiac T2* should be performed as early as 6 years old

    Terahertz All-Optical Modulation in a Silicon-Polymer Hybrid System

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    Although Gigahertz-scale free-carrier modulators have been previously demonstrated in silicon, intensity modulators operating at Terahertz speeds have not been reported because of silicon's weak ultrafast optical nonlinearity. We have demonstrated intensity modulation of light with light in a silicon-polymer integrated waveguide device, based on the all-optical Kerr effect - the same ultrafast effect used in four-wave mixing. Direct measurements of time-domain intensity modulation are made at speeds of 10 GHz. We showed experimentally that the ultrafast mechanism of this modulation functions at the optical frequency through spectral measurements, and that intensity modulation at frequencies in excess of 1 THz can be obtained in this device. By integrating optical polymers through evanescent coupling to high-mode-confinement silicon waveguides, we greatly increase the effective nonlinearity of the waveguide for cross-phase modulation. The combination of high mode confinement, multiple integrated optical components, and high nonlinearities produces all-optical ultrafast devices operating at continuous-wave power levels compatible with telecommunication systems. Although far from commercial radio frequency optical modulator standards in terms of extinction, these devices are a first step in development of large-scale integrated ultrafast optical logic in silicon, and are two orders of magnitude faster than previously reported silicon devices.Comment: Under consideration at Nature Material

    Isolation and characterization of polymorphic microsatellite markers from Coilia ectenes

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    ABSTRACT. Coilia ectenes is an important anadromous species that is an important resource at risk of extinction because of over-fishing, pollution, and coastal construction. To evaluate the genetic diversity of C. ectenes for use in breeding programs, elite microsatellite-enriched libraries were constructed and novel microsatellite markers were developed, and applied to genetically detect wild populations. Out of 92 randomly selected and sequenced clones, 89 contained a CA or GA repeat motif. Twenty-two pairs of primers were designed to investigate the polymorphism and genetic structure of a wild population collected from the Yellow River estuary, China. It was found that 2 loci were monomorphic and 20 loci were polymorphic. The number of alleles per polymorphic loci ranged from 3 to 13, with an average of 7.9. The expected heterozygosity per locus ranged from 0.05 to 0.89, with an average of 0.68. The isolated polymorphic markers are expected to be of use in future genetic breeding programs for C. ectenes, and in the assessment of genetic variation within this species

    High-Utilisation Nanoplatinum Catalyst (Pt@cPIM) Obtained via Vacuum Carbonisation in a Molecularly Rigid Polymer of Intrinsic Microporosity

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    Polymers of intrinsic microporosity (PIM or here PIM-EA-TB) offer a highly rigid host environment into which hexachloroplatinate(IV) anions are readily adsorbed and vacuum carbonised (at 500 °C) to form active embedded platinum nanoparticles. This process is characterised by electron and optical microscopy, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and electrochemical methods, which reveal that the PIM microporosity facilitates the assembly of nanoparticles of typically 1.0 to 2.5-nm diameter. It is demonstrated that the resulting carbonised “Pt@cPIM” from drop-cast films of ca. 550-nm average thickness, when prepared on tin-doped indium oxide (ITO), contain not only fully encapsulated but also fully active platinum nanoparticles in an electrically conducting hetero-carbon host. Alternatively, for thinner films (50–250 nm) prepared by spin coating, the particles become more exposed due to additional loss of the carbon host. In contrast to catalyst materials prepared by vacuum-thermolysed hexachloroplatinate(IV) precursor, the platinum nanoparticles within Pt@cPIM retain high surface area, electrochemical activity and high catalyst efficiency due to the molecular rigidity of the host. Data are presented for oxygen reduction, methanol oxidation and glucose oxidation, and in all cases, the high catalyst surface area is linked to excellent catalyst utilisation. Robust transparent platinum-coated electrodes are obtained with reactivity equivalent to bare platinum but with only 1 μg Pt cm−2 (i.e. ~100% active Pt nanoparticle surface is maintained in the carbonised microporous host). [Figure not available: see fulltext.

    Higher-order multipole amplitude measurement in ψ(2S)γχc2\psi(2S)\to\gamma\chi_{c2}

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    Using 106×106106\times10^6 ψ(2S)\psi(2S) events collected with the BESIII detector at the BEPCII storage ring, the higher-order multipole amplitudes in the radiative transition ψ(2S)γχc2γππ/γKK\psi(2S)\to\gamma\chi_{c2}\to\gamma\pi\pi/\gamma KK are measured. A fit to the χc2\chi_{c2} production and decay angular distributions yields M2=0.046±0.010±0.013M2=0.046\pm0.010\pm0.013 and E3=0.015±0.008±0.018E3=0.015\pm0.008\pm0.018, where the first errors are statistical and the second systematic. Here M2M2 denotes the normalized magnetic quadrupole amplitude and E3E3 the normalized electric octupole amplitude. This measurement shows evidence for the existence of the M2M2 signal with 4.4σ4.4\sigma statistical significance and is consistent with the charm quark having no anomalous magnetic moment.Comment: 14 pages, 4 figure
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