Stopping and straggling of 60-250-keV backscattered protons on nanometric Pt films

The stopping power and straggling of backscattered protons on nanometric Pt films were measured at low to medium energies (60-250 keV) by using the medium-energy ion scattering technique. The stopping power results are in good agreement with the most recent measurements by Primetzhofer Phy s. Rev. B 86, 094102 (2012) and are well described by the free electron gas model at low projectile energies. Nevertheless, the straggling results are strongly underestimated by well-established formulas up to a factor of two. Alternatively, we propose a model for the energy-loss straggling that takes into account the inhomogeneous electron-gas response, based on the electron-loss function of the material, along with bunching effects. This approach yields remarkable agreement with the experimental data, indicating that the observed enhancement in energy-loss straggling is due to bunching effects in an inhomogeneous electron system. Nonlinear effects are of minor importance for the energy-loss straggling

Disponibilidade de fósforo, cobre, manganes e zinco em três solos incubados com carbonato de cálcio.

Os solos tropicais são normalmente ácidos, devido a lixiviação de bases e ausência de minerais responsáveis pela reposição dessas bases (VITTI; PROCHNOW, 1996). Além da ocorrência natural, as práticas agrícolas de manejo podem acentuar a acidez do solo, Para Gama (1998) a recomendação correta de calcário tem grande importância, principalmente para que se tenhà uma adequada correção da acidez e aumente a eficiência dos fertilizantes. Isso torna-se mais relevante no caso do fósforo e dos micronutrientes metálicos, pois a acidez do solo exerce grande influência no controle da disponibilidade destes nutrientes. Segundo Lopes (1989) além da acidez, fatores como tipo e quantidade de argila do solo também influenciam a disponibilidade de P no mesmo. De acordo com Abreu et aI. (2001), o cobre tem sua disponibilidade controlada pela reação do solo e por altos teores de matéria orgânica que pode complexa-lo. No caso do manganês baixos teores naturais e o desequilíbrio de outros metais (Ca, Fe, Mg) condicionam a sua disponibilidade no solo (BORKET et al., 2001). Para estes autores a correção da acidez dos solos sob cerrados, com elevação da saturação por bases a 70% contribuiu para o surgimento de deficiências de manganês na cultura da soja, daí a recomendação atual de considerar 50% de saturação por bases como valor mais adequado àquela cultura. Quanto ao comportamento do zinco, Abreu et al.(200 1) relacionam que além da acidez baixa, altos teores de fósforo e matéria orgânica, podem reduzir a sua disponibilidade no solo. Esse trabalho teve como objetivo avaliar a disponibilidade de fósforo, cobre, manganês e zinco em três solos incubados com CaC03

Characterization of oxygen self-diffusion in TiO2 resistive-switching layers by nuclear reaction profiling

Oxygen self-diffusion was investigated in TiO2 layers employed for resistive-switching memories using resonant nuclear reaction profiling (NRP) and 18O labeling. The layers were grown using physical vapor deposition technique (sputtering) and were polycrystalline. The diffusivity was measured over the temperature range 600–800 °C and the activation energy for oxygen self-diffusion in sputter-deposited TiO2 films determined to be 1.09 ± 0.16 eV, a value consistent with results obtained by previous studies (Marmitt et al., 2017).This study was financed in part by the Coordena de Aperfei oamento de Pessoal de Nvel Superior – Brasil (CAPES) – Finance Code 001, by CNPq and PRONEX-FAPERGS. We acknowledge support from the NCRIS ANFF and Heavy-Ion Accelerator Capabilities, with particular thanks to Dr. Fouad Karouta for the deposition of the (Si3N4) at ANU. RGE and MV further acknowledge the ARC funding program for financial support

Hepcidin Expression in Iron Overload Diseases Is Variably Modulated by Circulating Factors

Hepcidin is a regulatory hormone that plays a major role in controlling body iron homeostasis. Circulating factors (holotransferrin, cytokines, erythroid regulators) might variably contribute to hepcidin modulation in different pathological conditions. There are few studies analysing the relationship between hepcidin transcript and related protein expression profiles in humans. Our aims were: a. to measure hepcidin expression at either hepatic, serum and urinary level in three paradigmatic iron overload conditions (hemochromatosis, thalassemia and dysmetabolic iron overload syndrome) and in controls; b. to measure mRNA hepcidin expression in two different hepatic cell lines (HepG2 and Huh-7) exposed to patients and controls sera to assess whether circulating factors could influence hepcidin transcription in different pathological conditions. Our findings suggest that hepcidin assays reflect hepatic hepcidin production, but also indicate that correlation is not ideal, likely due to methodological limits and to several post-trascriptional events. In vitro study showed that THAL sera down-regulated, HFE-HH and C-NAFLD sera up-regulated hepcidin synthesis. HAMP mRNA expression in Huh-7 cells exposed to sera form C-Donors, HFE-HH and THAL reproduced, at lower level, the results observed in HepG2, suggesting the important but not critical role of HFE in hepcidin regulation

Stopping and straggling of 60-250-keV backscattered protons on nanometric Pt films

The stopping power and straggling of backscattered protons on nanometric Pt films were measured at low to medium energies (60-250 keV) by using the medium-energy ion scattering technique. The stopping power results are in good agreement with the most recent measurements by Primetzhofer Phys. Rev. B 86, 094102 (2012) and are well described by the free electron gas model at low projectile energies. Nevertheless, the straggling results are strongly underestimated by well-established formulas up to a factor of two. Alternatively, we propose a model for the energy-loss straggling that takes into account the inhomogeneous electron-gas response, based on the electron-loss function of the material, along with bunching effects. This approach yields remarkable agreement with the experimental data, indicating that the observed enhancement in energy-loss straggling is due to bunching effects in an inhomogeneous electron system. Nonlinear effects are of minor importance for the energy-loss straggling.This study was financed in part by: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001; Conselho Nacional de Desenvolvimento Cientfico e Tecnológico - Brazil (CNPq) Projects No. 141833/2017-3, No. 160018/2019-6, No. 406750/2016- 5 and No. 404301/2016-9; and PRONEX-FAPERGS. J.M., P.L.G., and F.F.S. acknowledge support by RADIATE project under the Grant Agreement 824096 from the EU Research and Innovation program HORIZON 2020. M.V. acknowledges the Australian Research Council - Australia (ARC) funding program for financial support. P.L.G. and F.F.S. acknowledge D. Primetzhofer for the enlightening discussion

Search for the exotic Ξ−−(1860)\Xi^{--}(1860) Resonance in 340GeV/c Σ−\Sigma^--Nucleus Interactions

We report on a high statistics search for the $\Xi^{--}(1860)$ resonance in $\Sigma^-$-nucleus collisions at 340GeV/c. No evidence for this resonance is found in our data sample which contains 676000 $\Xi^-$ candidates above background. For the decay channel $\Xi^{--}(1860) \to \Xi^-\pi^-$ and the kinematic range 0.15$<x_F<$0.9 we find a 3$\sigma$ upper limit for the production cross section of 3.1 and 3.5 $\mu$b per nucleon for reactions with carbon and copper, respectively.Comment: 5 pages, 4 figures, modification of ref. 43 and 4