636 research outputs found

    Site specific spin dynamics in BaFe2As2: tuning the ground state by orbital differentiation

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    The role of orbital differentiation on the emergence of superconductivity in the Fe-based superconductors remains an open question to the scientific community. In this investigation, we employ a suitable microscopic spin probe technique, namely Electron Spin Resonance (ESR), to investigate this issue on selected chemically substituted BaFe2_{2}As2_{2} single crystals. As the spin-density wave (SDW) phase is suppressed, we observe a clear increase of the Fe 3dd bands anisotropy along with their localization at the FeAs plane. Such an increase of the planar orbital content interestingly occurs independently on the chemical substitution responsible for suppressing the SDW phase. As a consequence, the magnetic fluctuations combined with the resultant particular symmetry of the Fe 3dd bands are propitious ingredients to the emergence of superconductivity in this class of materials.Comment: 6 pages, 5 figure

    Distinct high-T transitions in underdoped Ba1−x_{1-x}Kx_{x}Fe2_{2}As2_{2}

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    In contrast to the simultaneous structural and magnetic first order phase transition T0T_{0} previously reported, our detailed investigation on an underdoped Ba0.84_{0.84}K0.16_{0.16}Fe2_{2}As2_{2} single crystal unambiguously revealed that the transitions are not concomitant. The tetragonal (τ\tau: I4/mmm) - orthorhombic (ϑ\vartheta: Fmmm) structural transition occurs at TS≃T_{S}\simeq 110 K, followed by an adjacent antiferromagnetic (AFM) transition at TN≃T_{N}\simeq 102 K. Hysteresis and coexistence of the τ\tau and ϑ\vartheta phases over a finite temperature range observed in our NMR experiments confirm the first order character of the structural transition and provide evidence that both TST_{S} and TNT_{N} are strongly correlated. Our data also show that superconductivity (SC) develops in the ϑ\vartheta phase below TcT_{c} = 20 K and coexists with long range AFM. This new observation, TS≠TNT_{S}\neq T_{N}, firmly establishes another similarity between the hole-doped BaFe2_{2}As2_{2} via K substitution and the electron-doped iron-arsenide superconductors.Comment: 4 pages, 3 figure

    Hematopoetic stem cell transplantation for solid tumors in Europe

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    Background: Hematopoetic stem cell transplants (HSCT) are discussed as treatment options for patients with solid tumors. Transplant numbers have changed substantially over the last decade, few controlled studies are available and different opinions prevail. Objective information on current practice is needed. Patients and methods: Data from 27 902 HSCT for solid tumors (2% allogeneic, 98% autologous), collected by the European Group for Blood and Marrow Transplantation (EBMT) activity survey from 1991 to 2002 were used to assess trends, transplant rates and coefficient of variation of transplant rates in Europe. Results: Transplant numbers increased from 536 in 1991 to 4154 in 1997 and decreased to 1913 in 2002. Indications were neuroblastoma (2504 HSCT; 9%), glioma (662 HSCT; 2%), soft tissue sarcoma (1253 HSCT; 4%), germ cell cancer (3291 HSCT; 12%), breast cancer (13 524 HSCT; 48%), Ewing's sarcoma (1896 HSCT; 7%), lung cancer (387 HSCT; 1%), ovarian cancer (845 HSCT; 3%) and other solid tumors (3540 HSCT; 14%). Allogeneic cells were used in <20 cases up to 1997; since then allogeneic HSCT increased to 159 in 2002, mainly for renal cell carcinoma. Low coefficients of variation in transplant rates (<60%) are observed for Ewing's sarcoma (<56.5%), suggesting consensus for this indication. Conclusions: These data give an overview on current practice of HSCT for solid tumors in Europe. They provide objective information for health-care providers and patient counsellin

    Possible unconventional superconductivity in substituted BaFe2_{2}As2_{2} revealed by magnetic pair-breaking studies

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    The possible existence of a sign-changing gap symmetry in BaFe2_{2}As2_{2}-derived superconductors (SC) has been an exciting topic of research in the last few years. To further investigate this subject we combine Electron Spin Resonance (ESR) and pressure-dependent transport measurements to investigate magnetic pair-breaking effects on BaFe1.9M0.1_{1.9}M_{0.1}As2_{2} (M=M= Mn, Co, Cu, and Ni) single crystals. An ESR signal, indicative of the presence of localized magnetic moments, is observed only for M=M= Cu and Mn compounds, which display very low SC transition temperature (TcT_{c}) and no SC, respectively. From the ESR analysis assuming the absence of bottleneck effects, the microscopic parameters are extracted to show that this reduction of TcT_{c} cannot be accounted by the Abrikosov-Gorkov pair-breaking expression for a sign-preserving gap function. Our results reveal an unconventional spin- and pressure-dependent pair-breaking effect and impose strong constraints on the pairing symmetry of these materials

    Antibacterial Property of Hanguana Malayana (Bakong) Crude Leaf Ethanolic Extract against Staphylococcus Aureus

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    Hanguana Malayana, known as Bakong plant is an invasive macrophytic plant found in few regions of the Philippines. Due to its mode of propagation, it occupies large spaces and it invades the space that’s allotted for the crops of local farmers. Hence, the researchers investigate this plant for beneficial uses. In this study, the effect of the different concentrations of H. malayana crude ethanolic leaf extract on S.aureus is evaluated on the basis of the study stating that the plant is a potential resources of bioactive phytoconstituents. The bioactive compounds shows synergistic impact that made it have an compelling antibacterial property against Staphylococcus aureus. In this think about, it was as it were demonstrated to have antibacterial property against gram-positive microbes, Staphylococcus aureus. This research concluded that the Hanguana malayana crude leaf ethanolic extract has an antibacterial property against Staphylococcus aureus

    Electron spin resonance of GD3+ in three dimensional topological insulator BI2SE3

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    Bi2Se3 has been claimed to be a three dimensional topological insulator (TI) with topologically protected metallic surface states with exotic properties. We have performed electron spin resonance (ESR) measurements on Gd3+ doped (x approximate to 0.01) Bi2Se3 single crystal grown from stoichiometric melt. For the studied crystals, our preliminary results revealed a partly resolved Gd3+ fine structure spectrum with Dysonian (metallic character) lines. At room temperature, the central line has a g approximate to 1.98, a linewidth Delta H approximate to 95 G and the spectra have a overall splitting of roughly 1300 Oe. As the temperature is decreased, the Gd3+ ESR Delta H of the central line presents a very small Korringa-like behavior b = Delta H/Delta T approximate to 0.013 Oe/K and nearly T-independent g-value. However, for T less than or similar to 40 K, Delta H shows a stronger narrowing effect evolving to Korringa-like behavior (b approximate to 0.15 Oe/K) for T less than or similar to 30 K. Concomitantly with the change in Delta H behavior, the Gd3+ central line g value starts to decrease reaching a value of 1.976 at T less than or similar to 4.2 K. The ESR results are discussed in terms of possible effects of protected topological surface states enlightened by complementary data from macroscopic measurements592International Conference on Strongly Correlated Electron Systems (SCES)2014-07FrançaUniv Grenoble, Grenobl

    Psychopharmacological Treatments for Mental Disorders in Patients with Neuromuscular Diseases: A Scoping Review

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    Mental disorders are observed in neuromuscular diseases, especially now that patients are living longer. Psychiatric symptoms may be severe and psychopharmacological treatments may be required. However, very little is known about pharmacotherapy in these conditions. We aimed to summarize the current knowledge on the use of psychopharmacological treatments for mental disorders in patients living with a neuromuscular disease. A scoping review was performed using the methodology of the Joanna Briggs Institute. Four databases were searched from January 2000 to July 2021. Articles were screened based on titles and abstracts. Full-text papers published in peer-reviewed journals in English were selected. Twenty-six articles met eligibility criteria, all being case reports/series focusing on the psychopharmacological control of psychiatric symptoms for the following conditions: myasthenia gravis (n = 11), Duchenne (n = 5) and Becker (n = 3) muscular dystrophy, mitochondrial disorders (n = 3), glycogen storage disease (n = 1), myotonic dystrophy (n = 1), hyperkalemic periodic paralysis (n = 1), and congenital myasthenic syndrome (n = 1). None of the articles provided details on the decision-making process to choose a specific drug/regimen or on follow-up strategies to monitor safety and efficacy. Larger studies showing real-world data would be required to guide consensus-based recommendations, thus improving current standards of care and, ultimately, the quality of life of patients and their families
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