764 research outputs found

    High Pressure And High Magnetic Field Studies Of The Electronic Transport Properties Of The Antiferromagnet Eu3ir4sn13

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    In this work we report the effects of hydrostatic pressure and magnetic field on the electronic transport properties of the antiferromagnetic compound Eu(3)Ir(4)Sni(3) (T-N similar to 10 K). Single crystals of Eu3Ir4Sn13 were synthesized using the Sn self-flux technique. DC electrical resistivity measurements as a function of temperature were performed by means of the four-probe technique. The high-temperature anomaly at T* similar to 57 K attributed to a structural distortion of the Sn1Sn2(12) cages in Eu3Ir4Sn13 is rapidly decreased to lower temperatures at a rate dT*/dP = 2 K/kbar, while the antiferromagnetic transition due to the Eu2+ ions is only weakly affected. Our data do not indicate any magnetoelastic effect associated with the structural instability at T*. Furthermore, the suppression of the lattice distortion by application of external pressure is not accompanied by the emergence of superconductivity, possibly due to strong magnetic correlations between the Eu2+ localized magnetic moments.59

    New sol-gel-derived magnetic bioactive glass-ceramics containing superparamagnetic hematite nanocrystals for hyperthermia application

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    Although the three main phases of iron oxide – hematite, maghemite, and magnetite – exhibit superparamagnetic properties at the nanoscale, only maghemite and magnetite phases have been explored in magnetic bioactive glass-ceramics aimed at applications in cancer treatment by hyperthermia. In this work, it is reported for the first time the superparamagnetic properties of hematite nanocrystals grown in a 58S bioactive glass matrix derived from sol-gel synthesis. The glass-ceramics are based on the (100-x)(58SiO2-33CaO-9P2O5)-xFe2O3 system (x = 10, 20 and 30 wt%). A thermal treatment leads to the growth of hematite (α-Fe2O3) nanocrystals, conferring superparamagnetic properties to the glass-ceramics, which is enough to produce heat under an external alternating magnetic field. Besides, the crystallization does not inhibit materials bioactivity, evidenced by the formation of calcium phosphate onto the glass-ceramic surface upon soaking in simulated body fluid. Moreover, their cytotoxicity is similar to other magnetic bioactive glass-ceramics reported in the literature. Finally, these results suggest that hematite nanocrystals' superparamagnetic properties may be explored in multifunctional glass-ceramics applied in bone cancer treatment by hyperthermia allied to bone regeneration

    The Role of Dietary Vitamin E in Experimental Listeria monocytogenes Infections in Turkeys

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    The current study was designed to determine if dietary vitamin E influenced either the gut clearance or levels of peripheral blood CD4+ and CD8+ T lymphocytes in adult turkeys experimentally infected with Listeria monocytogenes. Turkeys were fed vitamin E (0, 100, or 200 IU) from day of hatch to time of necropsy. After 6 wk on the experimental diet, turkeys were orally inoculated with L. monocytogenes (∼ 109 cfu). To monitor infection status, cloacal swabs were taken on selected days post-inoculation (DPI). At necropsy, samples of viscera, including liver, spleen, cecum, duodenum, ileum, and colon were collected and cultured for L. monocytogenes. In experiments 1 and 2, recovery of L. monocytogenes from cloacal swabs, tissues, and intestines from turkeys fed vitamin E was generally lower than that from turkeys fed the control diet, although these differences were not statistically significant. When data from both trials were combined, L. monocytogenes was cultured less frequently from cloacal swabs of the vitamin E-treated group (200 IU) on 2 and 3 DPI, when compared to controls (0 IU, P \u3c 0.01). There were no changes in virulence characteristics of L. monocytogenes cells, as measured by in vitro killing of Ped-2E9 cells, recovered from cloacal swabs or tissues of experimentally infected turkeys fed the control or a vitamin E treatment diet. Flow cytometric analysis indicated that CD4+ and CD8+ peripheral blood T lymphocytes were elevated at 6 and 8 DPI in infected turkeys given 200 IU vitamin E

    Towards understanding the variability in biospheric CO2 fluxes:Using FTIR spectrometry and a chemical transport model to investigate the sources and sinks of carbonyl sulfide and its link to CO2

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    Understanding carbon dioxide (CO2) biospheric processes is of great importance because the terrestrial exchange drives the seasonal and interannual variability of CO2 in the atmosphere. Atmospheric inversions based on CO2 concentration measurements alone can only determine net biosphere fluxes, but not differentiate between photosynthesis (uptake) and respiration (production). Carbonyl sulfide (OCS) could provide an important additional constraint: it is also taken up by plants during photosynthesis but not emitted during respiration, and therefore is a potential means to differentiate between these processes. Solar absorption Fourier Transform InfraRed (FTIR) spectrometry allows for the retrievals of the atmospheric concentrations of both CO2 and OCS from measured solar absorption spectra. Here, we investigate co-located and quasi-simultaneous FTIR measurements of OCS and CO2 performed at five selected sites located in the Northern Hemisphere. These measurements are compared to simulations of OCS and CO2 using a chemical transport model (GEOS-Chem). The coupled biospheric fluxes of OCS and CO2 from the simple biosphere model (SiB) are used in the study. The CO2 simulation with SiB fluxes agrees with the measurements well, while the OCS simulation reproduced a weaker drawdown than FTIR measurements at selected sites, and a smaller latitudinal gradient in the Northern Hemisphere during growing season when comparing with HIPPO (HIAPER Pole-to-Pole Observations) data spanning both hemispheres. An offset in the timing of the seasonal cycle minimum between SiB simulation and measurements is also seen. Using OCS as a photosynthesis proxy can help to understand how the biospheric processes are reproduced in models and to further understand the carbon cycle in the real world

    Molecular genetics and pathophysiology of 17 beta-hydroxysteroid dehydrogenase 3 deficiency.

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    Autosomal recessive mutations in the 17 beta-hydroxysteroid dehydrogenase 3 gene impair the formation of testosterone in the fetal testis and give rise to genetic males with female external genitalia. Such individuals are usually raised as females, but virilize at the time of expected puberty as the result of increases in serum testosterone. Here we describe mutations in 12 additional subjects/families with this disorder. The 14 mutations characterized to date include 10 missense mutations, 3 splice junction abnormalities, and 1 small deletion that results in a frame shift. Three of these mutations have occurred in more than 1 family. Complementary DNAs incorporating 9 of the 10 missense mutations have been constructed and expressed in reporter cells; 8 of the 9 missense mutations cause almost complete loss of enzymatic activity. In 2 subjects with loss of function, missense mutations testosterone levels in testicular venous blood were very low. Considered together, these findings strongly suggest that the common mechanism for testosterone formation in postpubertal subjects with this disorder is the conversion of circulating androstenedione to testosterone by one or more of the unaffected 17 beta-hydroxysteroid dehydrogenase isoenzymes

    Cosmic ray short burst observed with the Global Muon Detector Network (GMDN) on June 22, 2015

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    We analyze the short cosmic ray intensity increase ("cosmic ray burst": CRB) on June 22, 2015 utilizing a global network of muon detectors and derive the global anisotropy of cosmic ray intensity and the density (i.e. the omnidirectional intensity) with 10-minute time resolution. We find that the CRB was caused by a local density maximum and an enhanced anisotropy of cosmic rays both of which appeared in association with Earth's crossing of the heliospheric current sheet (HCS). This enhanced anisotropy was normal to the HCS and consistent with a diamagnetic drift arising from the spatial gradient of cosmic ray density, which indicates that cosmic rays were drifting along the HCS from the north of Earth. We also find a significant anisotropy along the HCS, lasting a few hours after the HCS crossing, indicating that cosmic rays penetrated into the inner heliosphere along the HCS. Based on the latest geomagnetic field model, we quantitatively evaluate the reduction of the geomagnetic cut-off rigidity and the variation of the asymptotic viewing direction of cosmic rays due to a major geomagnetic storm which occurred during the CRB and conclude that the CRB is not caused by the geomagnetic storm, but by a rapid change in the cosmic ray anisotropy and density outside the magnetosphere.Comment: accepted for the publication in the Astrophysical Journa

    High pressure and high magnetic field studies of the electronic transport properties of the antiferromagnet Eu3ir4sn13

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    In this work we report the effects of hydrostatic pressure and magnetic field on the electronic transport properties of the antiferromagnetic compound Eu(3)Ir(4)Sni(3) (T-N similar to 10 K). Single crystals of Eu3Ir4Sn13 were synthesized using the Sn self-flux technique. DC electrical resistivity measurements as a function of temperature were performed by means of the four-probe technique. The high-temperature anomaly at T* similar to 57 K attributed to a structural distortion of the Sn1Sn2(12) cages in Eu3Ir4Sn13 is rapidly decreased to lower temperatures at a rate dT*/dP = 2 K/kbar, while the antiferromagnetic transition due to the Eu2+ ions is only weakly affected. Our data do not indicate any magnetoelastic effect associated with the structural instability at T*. Furthermore, the suppression of the lattice distortion by application of external pressure is not accompanied by the emergence of superconductivity, possibly due to strong magnetic correlations between the Eu2+ localized magnetic moments592International Conference on Strongly Correlated Electron Systems (SCES)2014-07FrançaUniversité Grenoble Alpe
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