458 research outputs found

    Coexistence of Itinerant Electrons and Local Moments in Iron-Based Superconductors

    Full text link
    In view of the recent experimental facts in the iron-pnictides, we make a proposal that the itinerant electrons and local moments are simultaneously present in such multiband materials. We study a minimal model composed of coupled itinerant electrons and local moments to illustrate how a consistent explanation of the experimental measurements can be obtained in the leading order approximation. In this mean-field approach, the spin-density-wave (SDW) order and superconducting pairing of the itinerant electrons are not directly driven by the Fermi surface nesting, but are mainly induced by their coupling to the local moments. The presence of the local moments as independent degrees of freedom naturally provides strong pairing strength for superconductivity and also explains the normal-state linear-temperature magnetic susceptibility above the SDW transition temperature. We show that this simple model is supported by various anomalous magnetic properties and isotope effect which are in quantitative agreement with experiments.Comment: 7 pages, 4 figures; an expanded versio

    Raw Garlic Consumption and Risk of Liver Cancer: A Population-Based Case-Control Study in Eastern China.

    Get PDF
    Although the major risk factors for liver cancer have been established, preventive factors for liver cancer have not been fully explored. We evaluated the association between raw garlic consumption and liver cancer in a large population-based case-control study in Eastern China. The study was conducted in Jiangsu, China, from 2003 to 2010. A total of 2011 incident liver cancer cases and 7933 randomly selected population-controls were interviewed. Epidemiological data including raw garlic intake and other exposures were collected, and serum markers of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection were assayed. Overall, eating raw garlic twice or more per week was inversely associated with liver cancer, with an adjusted odds ratio (aOR) of 0.77 (95% confidence interval (CI): 0.62-0.96) compared to those ingesting no raw garlic or less than twice per week. In stratified analyses, high intake of raw garlic was inversely associated with liver cancer among Hepatitis B surface antigen (HBsAg) negative individuals, frequent alcohol drinkers, those having history of eating mold-contaminated food or drinking raw water, and those without family history of liver cancer. Marginal interactions on an additive scale were observed between low raw garlic intake and HBsAg positivity (attributable proportion due to interaction (AP) = 0.31, 95% CI: -0.01-0.62) and heavy alcohol drinking (AP = 0.28, 95% CI: 0.00-0.57). Raw garlic consumption is inversely associated with liver cancer. Such an association shed some light on the potential etiologic role of garlic intake on liver cancer, which in turn might provide a possible dietary intervention to reduce liver cancer in Chinese population

    Pressure-induced magnetic transition and volume collapse in FeAs superconductors: An orbital-selective Mott scenario

    Full text link
    Motivated by pressure experiments on FeAs-122 superconductors, we propose a scenario based on local-moment physics to explain the simultaneous disappearance of magnetism, reduction of the unit cell volume, and decrease in resistivity. In this scenario, the low-pressure magnetic phase derives from Fe moments, which become screened in the paramagnetic high-pressure phase. The quantum phase transition can be described as an orbital-selective Mott transition, which is rendered first order by coupling to the lattice, in analogy to a Kondo volume collapse. Spin-fluctuation driven superconductivity competes with antiferromagnetism and may be stabilized at low temperatures in the high-pressure phase. The ideas are illustrated by a suitable mean-field analysis of an Anderson lattice model.Comment: 9 pages, 3 figs; (v2) robustness of OS Mott transition vs. fragility of superconductivity discussed, final version to be publishe

    The Survey of H5N1 Flu Virus in Wild Birds in 14 Provinces of China from 2004 to 2007

    Get PDF
    The highly pathogenic H5N1 avian influenza emerged in the year 1996 in Asia, and has spread to Europe and Africa recently. At present, effective monitoring and data analysis of H5N1 are not sufficient in Chinese mainland.)) were obviously higher than those in other 13 provinces. The results of sequence analysis indicated that the 17 strains isolated from wild birds were distributed in five clades (2.3.1, 2.2, 2.5, 6, and 7), which suggested that genetic diversity existed among H5N1 viruses isolated from wild birds. The five isolates from Qinghai came from one clade (2.2) and had a short evolutionary distance with the isolates obtained from Qinghai in the year 2005.We have measured the prevalence of H5N1 virus in 56 species of wild birds in 14 provinces of China. Continuous monitoring in the field should be carried out to know whether H5N1 virus can be maintained by wild birds

    A High Resolution Genetic Map Anchoring Scaffolds of the Sequenced Watermelon Genome

    Get PDF
    As part of our ongoing efforts to sequence and map the watermelon (Citrullus spp.) genome, we have constructed a high density genetic linkage map. The map positioned 234 watermelon genome sequence scaffolds (an average size of 1.41 Mb) that cover about 330 Mb and account for 93.5% of the 353 Mb of the assembled genomic sequences of the elite Chinese watermelon line 97103 (Citrullus lanatus var. lanatus). The genetic map was constructed using an F8 population of 103 recombinant inbred lines (RILs). The RILs are derived from a cross between the line 97103 and the United States Plant Introduction (PI) 296341-FR (C. lanatus var. citroides) that contains resistance to fusarium wilt (races 0, 1, and 2). The genetic map consists of eleven linkage groups that include 698 simple sequence repeat (SSR), 219 insertion-deletion (InDel) and 36 structure variation (SV) markers and spans ∼800 cM with a mean marker interval of 0.8 cM. Using fluorescent in situ hybridization (FISH) with 11 BACs that produced chromosome-specifc signals, we have depicted watermelon chromosomes that correspond to the eleven linkage groups constructed in this study. The high resolution genetic map developed here should be a useful platform for the assembly of the watermelon genome, for the development of sequence-based markers used in breeding programs, and for the identification of genes associated with important agricultural traits

    Identification of a hypoxia-regulated miRNA signature in bladder cancer and a role for miR-145 in hypoxia-dependent apoptosis

    Get PDF
    Background: Hypoxia leads to the stabilisation of the hypoxia-inducible factor (HIF) transcription factor that drives the expression of target genes including microRNAs (miRNAs). MicroRNAs are known to regulate many genes involved in tumourigenesis. The aim of this study was to identify hypoxia-regulated miRNAs (HRMs) in bladder cancer and investigate their functional significance. Methods: Bladder cancer cell lines were exposed to normoxic and hypoxic conditions and interrogated for the expression of 384 miRNAs by qPCR. Functional studies were carried out using siRNA-mediated gene knockdown and chromatin immunoprecipitations. Apoptosis was quantified by annexin V staining and flow cytometry. Results: The HRM signature for NMI bladder cancer lines includes miR-210, miR-193b, miR-145, miR-125-3p, miR-708 and miR-517a. The most hypoxia-upregulated miRNA was miR-145. The miR-145 was a direct target of HIF-1a and two hypoxia response elements were identified within the promoter region of the gene. Finally, the hypoxic upregulation of miR-145 contributed to increased apoptosis in RT4 cells. Conclusions: We have demonstrated the hypoxic regulation of a number of miRNAs in bladder cancer. We have shown that miR- 145 is a novel, robust and direct HIF target gene that in turn leads to increased cell death in NMI bladder cancer cell lines

    Boosting hydrogen evolution performance by using a plasma-sputtered porous monolithic W2C@WC1−x/Mo film electrocatalyst

    Get PDF
    The establishment of an efficient and economic means of producing hydrogen via electrocatalytic water-splitting will facilitate the extensive commercialization of fuel cells, and the round-the-clock model of electrocatalytic hydrogen production will alleviate the intermittency issue associated with sustainable energy sources. To enable this feature of renewable hydrogen energy, the key point is to develop cheap, large-scale and high-performance hydrogen evolution electrocatalysts as an alternative to noble metals. Here, a simple and robust physically sputtering strategy is reported to massively prepare a porous and defect-enriched W2C@WC1−x film electrocatalyst on carbon cloth (CC) in a W, C and Ar ion plasma atmosphere. The preferential re-sputtering mechanism promotes the loss of activated W and C ions in plasma and extracts more C from plasma, resulting in the ultimate formation of a defective W2C@WC1−x film. The ratio of W2C to WC1−x increased and the particle size decreased when additional nano-scale thickness Mo sublayers were further incorporated. A monolithic and porous W2C@WC1−x/Mo multilayer film as a binder-free electrocatalyst on flexible CC is created. It exhibits excellent HER performance with a low overpotential of 58 mV vs. RHE to drive a current density of −10 mA cm−2, a low Tafel slope of 41 mV dec−1 and over 6 days of long-term running stability in 0.5 M H2SO4 solution. It outperforms most of the recently reported outstanding non-noble metal electrocatalysts. This work sheds light on a new route to regulate the tungsten-carbide catalyst morphology and composition with an aim to boost its HER activity

    Smoking and alcohol drinking increased the risk of esophageal cancer among Chinese men but not women in a high-risk population

    Get PDF
    Although the association for esophageal cancer with tobacco smoking and alcohol drinking has been well established, the risk appears to be less strong in China. To provide more evidence on the effect of smoking and alcohol consumption with esophageal cancer in China, particularly among Chinese women, a population-based case–control study has been conducted in Jiangsu, China, from 2003 to 2007. A total of 1,520 cases and 3,879 controls were recruited. Unconditional multivariate logistic regression analysis was applied. Results showed that the odds ratio (OR) and confidence interval (CI) for ever smoking and alcohol drinking were 1.57 (95% CI: 1.34–1.83) and 1.50 (95% CI: 1.29–1.74). Dose–response relationships were observed with increased intensity and longer duration of smoking/drinking. Risk of smoking and alcohol drinking at the highest joint level was 7.32 (95% CI: 4.58–11.7), when compared to those never smoked and never drank alcohol. Stratifying by genders, smoking and alcohol drinking increased the risk among men with an OR of 1.74 (95% CI: 1.44–2.09) and 1.76 (95% CI: 1.48–2.09); however, neither smoking nor alcohol consumption showed a significant association among women. In conclusion, smoking and alcohol drinking were associated with esophageal cancer risk among Chinese men, but not among Chinese women
    corecore