4,070 research outputs found

    Diverse Permian magmatism in the Tarim Block, NW China: Genetically linked to the Permian Tarim mantle plume?

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    Zircon U–Pb ages and geochemical data are reported for the Piqiang oxide-bearing ultramfic–mafic complex, the Bachu mafic dyke swarm, the Yingan and Kaipaizileike basalts and the Halajun A-type granites in the Tarim Block, Northwest China. The Piqiang complex and the Halajun A-type granites were emplaced at ca. 276 Ma and ca. 278 Ma, respectively. Together with previously reported geochronological data, the diverse intrusive and extrusive rocks in Tarim show a peak age at ca. 275 Ma. Elemental and Nd isotope geochemistry suggests that the spatially and temporally related Piqiang complex (including some dolerite dykes or stocks) and the Halajun A-type granites were formed via crystal fractionation/accumulation of a common plume-derived parental mafic magma (melting degree > 10%), coupled with variable extents of crustal contamination. Crystal fractionation/accumulation in one or several magma chambers resulted in the diversity of rocks types.The Bachu mafic dyke swarm shares a similar mantle source with the intrusive rocks in the Piqiang–Halajun area but with a relatively lower degree of partial melting (~ 5%). In contrast, the basalts were derived from a time-integrated, enriched lithospheric mantle source as suggested by their high-Ti, LREE- and LILE-enriched trace element signature and negative ΔNd(t) values (− 2.0 ~ −2.6). The synchronous yet diverse range of Permian igneous rocks in Tarim can best be accounted for by a Permian mantle plume, which is about 15 Ma earlier than the Emeishan plume in southwestern China.Research Highlights â–ș The ultramafic-mafic complex in Tarim gave a zircon U–Pb age of 276 Ma. â–ș The A-type granites in Tarim gave a zircon U–Pb age of ca. 278 Ma. â–ș The diverse Permian intrusive rocks originated from the sub-lithospheric mantle. â–ș The basalts originated from a time-integrated, enriched lithospheric mantle source. â–ș Both the intrusive and extrusive rocks are genetically related to a Permian mantle plume

    Association of NEDA-4 With No Long-term Disability Progression in Multiple Sclerosis and Comparison With NEDA-3: A Systematic Review and Meta-analysis

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    Esclerosis mĂșltiple; Discapacidad; NEDA-4Esclerosi mĂșltiple; Discapacitat; NEDA-4Multiple sclerosis; Disability; NEDA-4Background and Objectives No evidence of disease activity (NEDA)-4 has been suggested as a treatment target for disease-modifying therapy (DMT) in relapsing-remitting multiple sclerosis (RRMS). However, the ability of NEDA-4 to discriminate long-term outcomes in MS and how its performance compares with NEDA-3 remain uncertain. We conducted a systematic review and meta-analysis to evaluate (1) the association between NEDA-4 and no long-term disability progression in MS and (2) the comparative performance of NEDA-3 and NEDA-4 in predicting no long-term disability progression. Methods English-language abstracts and manuscripts were systematically searched in MEDLINE, Embase, and the Cochrane databases from January 2006 to November 2021 and reviewed independently by 2 investigators. We selected studies that assessed NEDA-4 at 1 or 2 years after DMT start and had at least 4 years of follow-up for determination of no confirmed disability progression. We conducted a meta-analysis using random-effects model to determine the pooled odds ratio (OR) for no disability progression with NEDA-4 vs EDA-4. For the comparative analysis, we selected studies that evaluated both NEDA-3 and NEDA-4 with at least 4 years of follow-up and examined the difference in the association of NEDA-3 and NEDA-4 with no disability progression. Results Five studies of 1,000 patients (3 interferon beta and 2 fingolimod) met inclusion criteria for both objectives. The median duration of follow-up was 6 years (interquartile range: 4–6 years). The prevalence of NEDA-4 ranged from 4.2% to 13.9% on interferon beta therapy and 24.9% to 25.1% on fingolimod therapy. The pooled OR for no long-term confirmed disability progression with NEDA-4 vs EDA-4 was 2.14 (95% confidence interval: 1.36–3.37; I2 = 0). We did not observe any significant difference between NEDA-4 and NEDA-3 in the comparative analyses. Discussion In patients with RRMS, NEDA-4 at 1–2 years was associated with 2 times higher odds of no long-term disability progression, at 6 years compared with EDA-4, but offered no advantage over NEDA-3

    Phase diagram as a function of doping level and pressure in Eu1−x_{1-x}Lax_xFe2_2As2_2 system

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    We establish the phase diagram of Eu1−x_{1-x}Lax_xFe2_2As2_2 system as a function of doping level x and the pressure by measuring the resistivity and magnetic susceptibility. The pressure can suppress the spin density wave (SDW) and structural transition very efficiently, while enhance the antiferromagnetic (AFM) transition temperature TN_N of Eu2+^{2+}. The superconductivity coexists with SDW order at the low pressure, while always coexists with the Eu2+^{2+} AFM order. The results suggests that Eu2+^{2+} spin dynamics is disentangeld with superconducting (SC) pairing taken place in the two-dimensional \emph{Fe-As} plane, but it can strongly affect superconducting coherence along c-axis

    Enhanced Superconductivity by Rare-earth Metal-doping in Phenanthrene

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    We successfully synthesized La- and Sm-doped phenanthrene powder samples and discovered superconductivity at TcT_{\rm c} around 6 K in them. The TcT_{\rm c}s are 6.1 K for LaPhenanthrene and 6.0 K for SmPhenanthrene, which are enhanced by about 1 K and 0.5 K compared to those in A3A_3Phenanthrene (AA=K and Rb) and in Ae1.5Ae_{1.5}Phenanthrene (AeAe = Sr and Ba) superconductors respectively. The superconductive shielding fractions for LaPhenanthrene and SmPhenanthrene are 46.1%and49.8 and 49.8%at2K,respectively.ThelittleeffectofthedopingofthemagneticionSm at 2 K, respectively. The little effect of the doping of the magnetic ion Sm^{3+}on on T_candthepositivepressuredependencecoefficienton and the positive pressure dependence coefficient on T_{\rm c}stronglysuggestsunconventionalsuperconductivityinthedopedphenanthrenesuperconductors.ThechargetransfertoorganicmoleculesfromdopantsofLaandSminducesaredshiftof7cm strongly suggests unconventional superconductivity in the doped phenanthrene superconductors. The charge transfer to organic molecules from dopants of La and Sm induces a redshift of 7 cm^{-1}perelectronforthemodeat1441cm per electron for the mode at 1441 cm^{-1}intheRamanspectra,whichisalmostthesameasthoseobservedin in the Raman spectra, which is almost the same as those observed in A_3Phenanthrene(Phenanthrene (A=KandRb)and=K and Rb) and Ae_{1.5}Phenanthrene(Phenanthrene (Ae$ = Sr and Ba) superconductors.Comment: 5 pages, 5 figure
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