367 research outputs found

    In situ confocal microprobe Raman spectroscopic studies on defective La-based complex oxides

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    The adsorption of O-2 over defective La2O3-based OCM catalysts with anionic vacancies, and the reaction of surface oxygen species with CH4 were studied by means of in situ confocal microprobe Raman spectra. The partially reduced oxygen species O-2(-), O-2(2-), O-2(delta-)(0<delta<1) and even the lattice oxygen ion O2- can be detected on the surface of O-2-pretreated La2O3-based catalysts. At lower temperatures (< 573 K) it is peroxide species O-2(2-) or O- that is more essential for the coupling of methane, while at higher temperatures the superoxide O-2(-) and lattice oxygen species O2- are rather important. It is easier for fluoride-containing La2O3-based catalysts to induce the oxygen species with fewer negative charges and the basicity of the catalyst surface is weakened, so that the C-2 selectivity for OCM reaction is improved

    Effect of laser remelting on microstructure and properties of WC reinforced Fe-based amorphous composite coatings by laser cladding

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    The WC reinforced Fe-based amorphous composite coatings were prepared by laser cladding with rectangular spot. The effect of laser remelting on the microstructure and properties of composite coatings was investigated. The results showed that laser remelting can reduce the cracks and porosities of the cladding coating and improve its surface quality. Large amounts of crystalline phases were precipitated at the top of the cladding and remelting coatings. However, the microstructure at the top of the remelting coating was finer compared to that at the top of the cladding coating. With increasing distance from the surface of substrate, the amorphous phase appeared within the remelting coating and large amounts of carbides rich in Fe and Mo, Fe23B6, gamma-Fe and Cr-9.1.Si-0.9 Slag phases were also precipitated in the remelting coating. As a result, the corrosion resistance of the remelting coating was higher than that of the cladding coating. The microhardness of the remelting coating was approximately 1.13 times higher than that of the cladding coating. (C) 2018 Elsevier Ltd. All rights reserved

    Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay

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    The decay channel Οˆβ€²β†’Ο€+Ο€βˆ’J/ψ(J/Οˆβ†’Ξ³ppΛ‰)\psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) is studied using a sample of 1.06Γ—1081.06\times 10^8 Οˆβ€²\psi^\prime events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the ppΛ‰p\bar{p} invariant mass spectrum. The enhancement can be fit with an SS-wave Breit-Wigner resonance function with a resulting peak mass of M=1861βˆ’13+6(stat)βˆ’26+7(syst)MeV/c2M=1861^{+6}_{-13} {\rm (stat)}^{+7}_{-26} {\rm (syst)} {\rm MeV/}c^2 and a narrow width that is Ξ“<38MeV/c2\Gamma<38 {\rm MeV/}c^2 at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics

    Disparities and risks of sexually transmissible infections among men who have sex with men in China: a meta-analysis and data synthesis.

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    BACKGROUND: Sexually transmitted infections (STIs), including Hepatitis B and C virus, are emerging public health risks in China, especially among men who have sex with men (MSM). This study aims to assess the magnitude and risks of STIs among Chinese MSM. METHODS: Chinese and English peer-reviewed articles were searched in five electronic databases from January 2000 to February 2013. Pooled prevalence estimates for each STI infection were calculated using meta-analysis. Infection risks of STIs in MSM, HIV-positive MSM and male sex workers (MSW) were obtained. This review followed the PRISMA guidelines and was registered in PROSPERO. RESULTS: Eighty-eight articles (11 in English and 77 in Chinese) investigating 35,203 MSM in 28 provinces were included in this review. The prevalence levels of STIs among MSM were 6.3% (95% CI: 3.5-11.0%) for chlamydia, 1.5% (0.7-2.9%) for genital wart, 1.9% (1.3-2.7%) for gonorrhoea, 8.9% (7.8-10.2%) for hepatitis B (HBV), 1.2% (1.0-1.6%) for hepatitis C (HCV), 66.3% (57.4-74.1%) for human papillomavirus (HPV), 10.6% (6.2-17.6%) for herpes simplex virus (HSV-2) and 4.3% (3.2-5.8%) for Ureaplasma urealyticum. HIV-positive MSM have consistently higher odds of all these infections than the broader MSM population. As a subgroup of MSM, MSW were 2.5 (1.4-4.7), 5.7 (2.7-12.3), and 2.2 (1.4-3.7) times more likely to be infected with chlamydia, gonorrhoea and HCV than the broader MSM population, respectively. CONCLUSION: Prevalence levels of STIs among MSW were significantly higher than the broader MSM population. Co-infection of HIV and STIs were prevalent among Chinese MSM. Integration of HIV and STIs healthcare and surveillance systems is essential in providing effective HIV/STIs preventive measures and treatments. TRIAL REGISTRATION: PROSPERO NO: CRD42013003721

    Genome wide mapping reveals PDE4B as an IL-2 induced STAT5 target gene in activated human PBMCs and lymphoid cancer cells

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    IL-2 is the primary growth factor for promoting survival and proliferation of activated T cells that occurs following engagement of the Janus Kinase (JAK)1-3/and Signal Transducer and Activator of Transcription (STAT) 5 signaling pathway. STAT5 has two isoforms: STAT5A and STAT5B ( commonly referred to as STAT5) which, in T cells, play redundant roles transcribing cell cycle and survival genes. As such, inhibition of STAT5 by a variety of mechanisms can rapidly induce apoptosis in certain lymphoid tumor cells, suggesting that it and its target genes represent therapeutic targets to control certain lymphoid diseases. To search for these molecules we aligned IL-2 regulated genes detected by Affymetrix gene expression microarrays with the STAT5 cistrome identified by chip-on-ChIP analysis in an IL-2-dependent human leukemia cell line, Kit225. Select overlapping genes were then validated using qRT(2)PCR medium-throughput arrays in human PHA-activated PBMCs. Of 19 putative genes, one key regulator of T cell receptor signaling, PDE4B, was identified as a novel target, which was readily up-regulated at the protein level (3 h) in IL-2 stimulated, activated human PBMCs. Surprisingly, only purified CD8+ primary T-cells expressed PDE4B, but not CD4+ cells. Moreover, PDE4B was found to be highly expressed in CD4+ lymphoid cancer cells, which suggests that it may represent a physiological role unique to the CD8+ and lymphoid cancer cells and thus might represent a target for pharmaceutical intervention for certain lymphoid diseases

    Soybean Trihelix Transcription Factors GmGT-2A and GmGT-2B Improve Plant Tolerance to Abiotic Stresses in Transgenic Arabidopsis

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    BACKGROUND:Trihelix transcription factors play important roles in light-regulated responses and other developmental processes. However, their functions in abiotic stress response are largely unclear. In this study, we identified two trihelix transcription factor genes GmGT-2A and GmGT-2B from soybean and further characterized their roles in abiotic stress tolerance. FINDINGS:Both genes can be induced by various abiotic stresses, and the encoded proteins were localized in nuclear region. In yeast assay, GmGT-2B but not GmGT-2A exhibits ability of transcriptional activation and dimerization. The N-terminal peptide of 153 residues in GmGT-2B was the minimal activation domain and the middle region between the two trihelices mediated the dimerization of the GmGT-2B. Transactivation activity of the GmGT-2B was also confirmed in plant cells. DNA binding analysis using yeast one-hybrid assay revealed that GmGT-2A could bind to GT-1bx, GT-2bx, mGT-2bx-2 and D1 whereas GmGT-2B could bind to the latter three elements. Overexpression of the GmGT-2A and GmGT-2B improved plant tolerance to salt, freezing and drought stress in transgenic Arabidopsis plants. Moreover, GmGT-2B-transgenic plants had more green seedlings compared to Col-0 under ABA treatment. Many stress-responsive genes were altered in GmGT-2A- and GmGT-2B-transgenic plants. CONCLUSION:These results indicate that GmGT-2A and GmGT-2B confer stress tolerance through regulation of a common set of genes and specific sets of genes. GmGT-2B also affects ABA sensitivity

    Exploring the Midgut Transcriptome and Brush Border Membrane Vesicle Proteome of the Rice Stem Borer, Chilo suppressalis (Walker)

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    The rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), is one of the most detrimental pests affecting rice crops. The use of Bacillus thuringiensis (Bt) toxins has been explored as a means to control this pest, but the potential for C. suppressalis to develop resistance to Bt toxins makes this approach problematic. Few C. suppressalis gene sequences are known, which makes in-depth study of gene function difficult. Herein, we sequenced the midgut transcriptome of the rice stem borer. In total, 37,040 contigs were obtained, with a mean size of 497 bp. As expected, the transcripts of C. suppressalis shared high similarity with arthropod genes. Gene ontology and KEGG analysis were used to classify the gene functions in C. suppressalis. Using the midgut transcriptome data, we conducted a proteome analysis to identify proteins expressed abundantly in the brush border membrane vesicles (BBMV). Of the 100 top abundant proteins that were excised and subjected to mass spectrometry analysis, 74 share high similarity with known proteins. Among these proteins, Western blot analysis showed that Aminopeptidase N and EH domain-containing protein have the binding activities with Bt-toxin Cry1Ac. These data provide invaluable information about the gene sequences of C. suppressalis and the proteins that bind with Cry1Ac

    FRA2 is a STAT5 target gene regulated by IL-2 in human CD4 T cells

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    Signal transducers and activators of transcription 5(STAT5) are cytokine induced signaling proteins, which regulate key immunological processes, such as tolerance induction, maintenance of homeostasis, and CD4 T-effector cell differentiation. In this study, transcriptional targets of STAT5 in CD4 T cells were studied by Chromatin Immunoprecipitation (ChIP). Genomic mapping of the sites cloned and identified in this study revealed the striking observation that the majority of STAT5-binding sites mapped to intergenic (>50 kb upstream) or intronic, rather than promoter proximal regions. Of the 105 STAT5 responsive binding sites identified, 94% contained the canonical (IFN-Ξ³ activation site) GAS motifs. A number of putative target genes identified here are associated with tumor biology. Here, we identified Fos-related antigen 2 (FRA2) as a transcriptional target of IL-2 regulated STAT5. FRA2 is a basic -leucine zipper (bZIP) motif 'Fos' family transcription factor that is part of the AP-1 transcription factor complex and is also known to play a critical role in the progression of human tumours and more recently as a determinant of T cell plasticity. The binding site mapped to an internal intron within the FRA2 gene. The epigenetic architecture of FRA2, characterizes a transcriptionally active promoter as indicated by enrichment for histone methylation marks H3K4me1, H3K4me2, H3K4me3, and transcription/elongation associated marks H2BK5me1 and H4K20me1. FRA2 is regulated by IL-2 in activated CD4 T cells. Consistently, STAT5 bound to GAS sequence in the internal intron of FRA2 and reporter gene assays confirmed IL-2 induced STAT5 binding and transcriptional activation. Furthermore, addition of JAK3 inhibitor (R333) or Daclizumab inhibited the induction in TCR stimulated cells. Taken together, our data suggest that FRA2 is a novel STAT5 target gene, regulated by IL-2 in activated CD4 T cells

    Precore Mutation of Hepatitis B Virus May Contribute to Hepatocellular Carcinoma Risk: Evidence from an Updated Meta-Analysis

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    BACKGROUND: Studies focused on the correlation of mutations in the genome of Hepatitis B Virus (HBV) like Pre-S mutation, Basal Core promoter (BCP), Enhancer II (EnhII), especially Precore mutation, with the risk of hepatocellular carcinoma (HCC) have triggered stiff controversies. With an increasing number of studies in this field recently, we conducted this meta-analysis to appraise the correlations. METHODS: We searched the commonly used databases both in English and Chinese till February 1(st), 2012. Meta-analysis was performed in fixed/random-effects models using STATA 10.0. Publication bias was examined through Egger's test and Begg's funnel plot. RESULTS: In total, 85 case-control studies were included involving 16745 HBV-infected patients, of whom 5781 had HCC. Statistically significant correlations were observed in Precore mutation G1896A (OR = 1.46, 95% confidence interval [CI] = 1.15-1.85, P(OR) = 0.002), G1899A (OR = 3.13, 95%CI = 2.38-4.13, P(OR)<0.001) and Pre-S mutation especially Pre-S1 deletion (OR = 2.94, 95%CI = 2.22 to 3.89) and Pre-S2 deletion (OR = 3.02, 95%CI = 2.03 to 4.50). Similar correlation existed between BCP double mutation A1762T/G1764A, T1753V, C1653T and HCC. In subgroup analysis, the Asians, genotype C or HBeAg positive patients with certain above mutations may be more susceptible to HCC. Besides, the mutations like G1896A and BCP double mutation may be associated with the progression of the liver diseases. CONCLUSIONS: Precore mutation G1896A, G1899A, deletions in Pre-S region as well as the other commonly seen mutations correlated with the increased risk of HCC, especially in Asians and may predict the progression of the liver disease
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