6,123 research outputs found

    A new 111 type iron pnictide superconductor LiFeP

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    A new iron pnictide LiFeP superconductor was found. The compound crystallizes into a Cu2Sb structure containing an FeP layer showing superconductivity with maximum Tc of 6K. This is the first 111 type iron pnictide superconductor containing no arsenic. The new superconductor is featured with itinerant behavior at normal state that could helpful to understand the novel superconducting mechanism of iron pnictide compounds.Comment: 3 figures + 1 tabl

    Spin reorientation in FeCrAs revealed by single-crystal neutron diffraction

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    The magnetic structure of the "nonmetallic metal" FeCrAs, a compound with the characters of both metals and insulators, was examined as a function of temperature using single-crystal neutron diffraction. The magnetic propagation vector was found to be k\mathit{k} = (1/3, 1/3, 0), and the magnetic reflections disppeared above TN\mathit{T_{N}} = 116(1) K. In the ground state, the Cr sublattice shows an in-plane spiral antiferromagnetic order. The moment sizes of the Cr ions were found to be small, due to strong magnetic frustration in the distorted Kagome lattice or the itinerant nature of the Cr magnetism, and vary between 0.8 and 1.4 μB\mu_{B} on different sites as expected for a spin-density-wave (SDW) type order. The upper limit of the moment on the Fe sublattice is estimated to be less than 0.1 μB\mu_{B}. With increasing temperature up to 95 K, the Cr moments cant out of the ab\mathit{ab} plane gradually, with the in-plane components being suppressed and the out-of-plane components increasing in contrast. This spin-reorientation of Cr moments can explain the dip in the c\mathit{c}-direction magnetic susceptibility and the kink in the magnetic order parameter at TO\mathit{T_{O}} ~ 100 K, a second magnetic transition which was unexplained before. We have also discussed the similarity between FeCrAs and the model itinerant magnet Cr, which exhibits spin-flip transitions and SDW-type antiferromagnetism.Comment: 8 pages, 7 figures, Accepted by Phys. Rev.

    Search for D to phi l nu and measurement of the branching fraction for D to phi pi

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    Using a data sample of integrated luminosity of about 33 pb1^{-1} collected around 3.773 GeV with the BESII detector at the BEPC collider, the semileptonic decays D+ϕe+νeD^+ \to \phi e ^+\nu_e, D+ϕμ+νμD^+ \to \phi \mu^+\nu_\mu and the hadronic decay D+ϕπ+D^+ \to \phi \pi^+ are studied. The upper limits of the branching fractions are set to be BF(D+ϕe+νe)<BF(D^+ \to \phi e ^+\nu_e) < 2.01% and BF(D+ϕμ+νμ)<BF(D^+ \to \phi \mu^+ \nu_\mu) < 2.04% at the 90% confidence level. The ratio of the branching fractions for D+ϕπ+D^+ \to \phi \pi^+ relative to D+Kπ+π+D^+ \to K^-\pi^+\pi^+ is measured to be 0.057±0.011±0.0030.057 \pm 0.011 \pm 0.003. In addition, the branching fraction for D+ϕπ+D^+ \to \phi \pi^+ is obtained to be (5.2±1.0±0.4)×103(5.2 \pm 1.0 \pm 0.4) \times 10^{-3}.Comment: 6 pages, 5 figures, to be published in Eur.Phys.J.

    Measurements of branching fractions for inclusive K0~/K0 and K*(892)+- decays of neutral and charged D mesons

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    Using the data sample of about 33 pb-1 collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied inclusive K0~/K0 and K*(892)+- decays of D0 and D+ mesons. The branching fractions for the inclusive K0~/K0 and K*(892)- decays are measured to be BF(D0 to K0~/K0 X)=(47.6+-4.8+-3.0)%, BF(D+ to K0~/K0 X)=(60.5+-5.5+-3.3)%, BF(D0 to K*- X)=(15.3+- 8.3+- 1.9)% and BF(D+ to K*- X)=(5.7+- 5.2+- 0.7)%. The upper limits of the branching fractions for the inclusive K*(892)+ decays are set to be BF(D0 to K*+ X)<3.6% and BF(D+ to K*+ X) <20.3% at 90% confidence level

    Gene Silencing via PDA/ERK2-siRNA-Mediated Electrospun Fibers for Peritendinous Antiadhesion

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    Sustained delivery of small interfering RNA (siRNA) is a challenge in gene silencing for managing gene-related disorders. Although nanoparticle-mediated electrospun fibers enable sustainable gene silencing, low efficiency, loss of biological activity, toxicity issues, and complex electrospinning techniques are all bottlenecks of these systems. Preventing peritendinous adhesion is crucial for their successful use, which involves blocking cellular signaling via physical barriers. Here, a multifunctional, yet structurally simple, cationic 2,6-pyridinedicarboxaldehyde-polyethylenimine (PDA)-mediated extracellular signal-regulated kinase (ERK)2-siRNA polymeric delivery system is reported, in the form of peritendinous antiadhesion electrospun poly-l-lactic acid/hyaluronan membranes (P/H), with the ability to perform sustained release of bioactive siRNA for long-term prevention of adhesions and ERK2 silencing. After 4 days of culture, the cell area and proliferation rate of chicken embryonic fibroblasts on siRNA+PDA+P/H membrane are significantly less than those on P/H and siRNA+P/H membranes. The in vivo results of average optical density of collagen type III (Col III) and gene expression of ERK2 and its downstream SMAD3 in the siRNA+PDA+P/H group are less than those of P/H and siRNA+P/H groups. Consequently, siRNA+PDA+P/H electrospun membrane can protect the bioactivity of ERK2-siRNA and release it in a sustained manner. Moreover, adhesion formation is inhibited by reducing fibroblast proliferation and Col III deposition, and downregulating ERK2 and its downstream SMAD3.S.L. and F.W. contributed equally to this work. This work was supported by the National Science Foundation of China (Grant Nos. 81772314, 51873107, and 81572099), Science and Technology Commission of Shanghai Municipality (Grant No. 15QA1403400 and 18ZR1434200), Shanghai Junior Outstanding Talent Program, Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support (Grant Nos. 20171906 and 17XJ11004), Foundation for Young Scientists of Shanghai Health and Family Planning Commission (Grant No. 2017YQ022), Shanghai Jiao Tong University “Medical and Research” Program, and Shanghai Jiao Tong University SMC Young Scholar Program B. This manuscript is a result of the project NORTE-01-0145-FEDER-000012, supported by Norte Portugal Regional Operational Programme (NORTE2020), under the PORTUGAL2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This work was financed by FEDER—Fundo Europeu de Desenvolvimento Regional funds through the COMPETE2020—Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT—Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior in the framework of the project “Institute for Research and Innovation in Health Sciences” (POCI-01-0145-FEDER-007274). S.L. and F.W. contributed equally to this work. This work was supported by the National Science Foundation of China (Grant Nos. 81772314, 51873107, and 81572099), Science and Technology Commission of Shanghai Municipality (Grant No. 15QA1403400 and 18ZR1434200), Shanghai Junior Outstanding Talent Program, Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support (Grant Nos. 20171906 and 17XJ11004), Foundation for Young Scientists of Shanghai Health and Family Planning Commission (Grant No. 2017YQ022), Shanghai Jiao Tong University ?Medical and Research? Program, and Shanghai Jiao Tong University SMC Young Scholar Program B. This manuscript is a result of the project NORTE-01-0145-FEDER-000012, supported by Norte Portugal Regional Operational Programme (NORTE2020), under the PORTUGAL2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This work was financed by FEDER?Fundo Europeu de Desenvolvimento Regional funds through the COMPETE2020?Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT?Funda??o para a Ci?ncia e a Tecnologia/Minist?rio da Ci?ncia, Tecnologia e Ensino Superior in the framework of the project ?Institute for Research and Innovation in Health Sciences? (POCI-01-0145-FEDER-007274)
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