Room temperature spin filtering in epitaxial cobalt-ferrite tunnel barriers

We report direct experimental evidence of room temperature spin filtering in magnetic tunnel junctions (MTJs) containing CoFe2O4 tunnel barriers via tunneling magnetoresistance (TMR) measurements. Pt(111)/CoFe2O4(111)/gamma-Al2O3(111)/Co(0001) fully epitaxial MTJs were grown in order to obtain a high quality system, capable of functioning at room temperature. Spin polarized transport measurements reveal significant TMR values of -18% at 2 K and -3% at 290 K. In addition, the TMR ratio follows a unique bias voltage dependence that has been theoretically predicted to be the signature of spin filtering in MTJs containing magnetic barriers. CoFe2O4 tunnel barriers therefore provide a model system to investigate spin filtering in a wide range of temperatures.Comment: 6 pages, 3 figure

Experimental application of sum rules for electron energy loss magnetic chiral dichroism

We present a derivation of the orbital and spin sum rules for magnetic circular dichroic spectra measured by electron energy loss spectroscopy in a transmission electron microscope. These sum rules are obtained from the differential cross section calculated for symmetric positions in the diffraction pattern. Orbital and spin magnetic moments are expressed explicitly in terms of experimental spectra and dynamical diffraction coefficients. We estimate the ratio of spin to orbital magnetic moments and discuss first experimental results for the Fe L_{2,3} edge.Comment: 11 pages, 2 figure

A new access control unit for GANIL and SPIRAL 2

International audienceFor the GANIL safety revaluation and the new project of accelerator SPIRAL 2, it was decided to replace theexisting access control system for radiological controlled areas. These areas are all cyclotron rooms and experimental areas. The existing system is centralized around VME cards. Updating is becoming very problematic. The new UGA (access control unit) will becomposed of a pair of PLC to ensure the safety of each room. It will be supplemented by a system UGB (radiological control unit) that will assure the radiological monitoring of the area concerned

Quantitative TEM imaging of the magnetostructural and phase transitions in FeRh thin film systems

Equi-atomic FeRh is a very interesting material as it undergoes a magnetostructural transition from an antiferromagnetic (AF) to a ferromagnetic (FM) phase between 75-105 °C. Its ability to present phase co-existence separated by domain walls (DWs) above room temperature provides immense potential for exploitation of their DW motion in spintronic devices. To be able to effectively control the DWs associated with AF/FM coexistence in FeRh thin films we must fully understand the magnetostructural transition and thermomagnetic behaviour of DWs at a localised scale. Here we present a transmission electron microscopy investigation of the transition in planar FeRh thin-film samples by combining differential phase contrast (DPC) magnetic imaging with in situ heating. We perform quantitative measurements from individual DWs as a function of temperature, showing that FeRh on NiAl exhibits thermomagnetic behaviour consistent with the transition from AF to FM. DPC imaging of an FeRh sample with HF-etched substrate reveals a state of AF/FM co-existence and shows the transition from AF to FM regions proceeds via nucleation of small vortex structures, which then grow by combining with newly nucleated vortex states into larger complex magnetic domains, until it is in a fully-FM state

MIF Participates in Toxoplasma gondii-Induced Pathology Following Oral Infection

BACKGROUND: Macrophage migration inhibitory factor (MIF) is essential for controlling parasite burden and survival in a model of systemic Toxoplasma gondii infection. Peroral T. gondii infection induces small intestine necrosis and death in susceptible hosts, and in many aspects resembles inflammatory bowel disease (IBD). Considering the critical role of MIF in the pathogenesis of IBD, we hypothesized that MIF participates in the inflammatory response induced by oral infection with T. gondii. METHODOLOGY/PRINCIPAL FINDINGS: Mif deficient (Mif(-/-)) and wild-type mice in the C57Bl/6 background were orally infected with T. gondii strain ME49. Mif(-/-) mice had reduced lethality, ileal inflammation and tissue damage despite of an increased intestinal parasite load compared to wt mice. Lack of MIF caused a reduction of TNF-α, IL-12, IFN-γ and IL-23 and an increased expression of IL-22 in ileal mucosa. Moreover, suppressed pro-inflammatory responses at the ileal mucosa observed in Mif(-/-) mice was not due to upregulation of IL-4, IL-10 or TGF-β. MIF also affected the expression of matrix metalloproteinase-9 (MMP-9) but not MMP-2 in the intestine of infected mice. Signs of systemic inflammation including the increased concentrations of inflammatory cytokines in the plasma and liver damage were less pronounced in Mif(-/-) mice compared to wild-type mice. CONCLUSION/SIGNIFICANCE: In conclusion, our data suggested that in susceptible hosts MIF controls T. gondii infection with the cost of increasing local and systemic inflammation, tissue damage and death

Exigência de treonina digestível para suínos machos castrados dos 15 aos 30 kg

Dois experimentos com o objetivo de determinar a exigência de treonina digestível verdadeira para suínos machos castrados dos 15 aos 30 kg foram realizados. No primeiro (ensaio de digestibilidade) foram usados oito suínos machos castrados, com peso médio inicial de 30,3 kg PV, previamente submetidos à cirurgia de anastomose íleo retal, distribuídos em delineamento em blocos ao acaso, com dois tratamentos, quatro repetições e um animal por unidade experimental. Os tratamentos consistiram de uma dieta basal, com 15,7% de proteína bruta (PB) e 0,49% de treonina total, e uma dieta isenta de proteína, para determinar o coeficiente de digestibilidade ileal verdadeira da treonina da dieta basal. No segundo experimento, 40 suínos mestiços, machos castrados, com peso inicial médio de 15,3 kg PV, foram distribuídos em delineamento experimental de blocos ao acaso, com cinco tratamentos (0,49; 0,54; 0,59; 0,64; e 0,69% de treonina total), quatro repetições e dois animais por unidade experimental. Por meio das características de desempenho e teor de uréia no soro sangüíneo e do modelo quadrático e, ou, o descontínuo LRP, foi obtido o valor de 0,63% como a exigência de treonina total para suínos machos castrados dos 15 aos 30 kg. Ao considerar o coeficiente de digestibilidade ileal verdadeira da treonina da dieta basal (84,6%) determinado no ensaio de digestibilidade e o coeficiente de digestibilidade de 100% para a treonina sintética suplementada na ração, foi obtido o valor de 0,56% como exigência de treonina digestível verdadeira.Two studies were conducted to determine the true digestible threonine requirement for barrows from 15 to 30 kg live weight (LW). In the first (digestibility trial) were used eight barrows, averaging 30,3 kg LW initial weight, submitted previous to the ileum-rectal anastomosis surgery, were allotted to a randomized block design, with two treatments, four replicates and one animal per experimental unit. The treatments consisted of a basal diet, with 15.7% of crude protein (CP) and .49% of total threonine, and one a protein free diet, to determine the coefficient of true ileal digestibility of threonine in the basal diet. In the second experiment, 40 crossbred pigs, barrows, averaging 15.3 kg initial weight were allotted to a randomized block design, with five treatments (.49, .54, .59, .64, e .69% of total threonine), four replicates and two animals per experimental unit. Using performance traits and serum urea level and applying the quadratic and/or the broken line models, a requirement value of .63% total threonine for 15 to 30 kg barrows was obtained . Considering the threonine basal diet coefficient of true ileal digestibility (84.6%) and the supplemented crystalline threonine digestibility coefficient of 100%, a requirement value of .56% true digestible threonine was obtained