Determinação de ph e potássio em solos do meio norte de mato grosso utilizando eletrodos seletivos de íons

Amostragens de solo em grades regulares na agricultura de precisão são comumente utilizadas comercialmente em campos na região meio norte de Mato Grosso com sucesso. Porém, a confiabilidade dos mapas depende muito da densidade amostral, sendo mais confiáveis quando são mais intensivamente amostrados. Além da limitação técnica da utilização da krigagem com poucos pontos, existe uma necessidade de baratear o custo laboratorial de amostragens intensas. Neste sentido, o objetivo desde trabalho foi determinar o teor de pH e potássio em solos utilizando eletrodos seletivos de íons e também realizar uma comparação de mapas gerados por amostras laboratoriais convencionais comparadas com amostras medidas com eletrodos seletivos de íons. Foram realizadas amostragens em grades regulares de 4 ha em talhões no meio norte de Mato Grosso tentando cobrir uma amplitude de solos representativos da região, sendo realizadas 9 subamostras em cada 4 ha. As amostras foram enviadas para laboratório comercial e também realizadas medidas diretas com eletrodos de íons seletivos em bancada. Resultados preliminares mostram boas correlações entre os métodos, sendo r=0.56 e 0.61, para pH e potássio, respectivamente. Comparações espaciais mostram que além da similaridade entre os mapas houve uma tendência de suavização dos valores para medições feitas com os eletrodos, mostrando mais coerência das manchas dos teores no solo

Magnetic properties of Co film in Pt/Co/Cr₂O₃/Pt structure

Magnetic properties of Co film in Pt/Co/α-Cr₂O₃/Pt/α-Al₂O₃ structure were investigated. Co layer thickness tCo dependence of perpendicular magnetic anisotropy energy density K reveals that the bulk magnetic anisotropy plays an important role in the system in addition to the interfacial anisotropy. Damping constant α monotonically increases with the decrease of tCo but not proportionally to 1/tCo. Both K and α increase with the increase of Pt layer thickness tPt from 3 nm to 5 nm and keeps almost constant in the tPt range between 5 nm to 20 nm. These results are of importance to understand the magnetization switching behavior driven by the magneto-electric (ME) effect as well as to design the spintronics device using the ME effect.T. V. A. Nguyen, Y. Shiratsuchi, H. Sato, S. Ikeda, T. Endoh, and Y. Endo, AIP Advances 10, 015152 (2020); https://doi.org/10.1063/1.5130439

Giant magnetoelectric effect in an L 2₁-ordered Co₂FeSi/Pb(Mg₁/₃Nb₂/₃)O₃-PbTiO₃ multiferroic heterostructure

We experimentally show a giant magnetoelectric (ME) effect at room temperature in an interfacial multiferroic heterostructure consisting of L2₁-ordered Co₂FeSi and Pb(Mg₁/₃Nb₂/₃)O₃-PbTiO₃ (PMN-PT). Molecular beam epitaxy growth at 400 °C enables us to obtain epitaxial and L2₁-ordered Co₂FeSi films on PMN-PT(001). For the epitaxial Co₂FeSi/PMN-PT heterostructure, the remanent magnetization state can be largely modulated by varying electric fields. We note that the room-temperature ME coupling coefficient (α) is estimated to be 6.0-6.3 × 10 - ⁶ s/m, comparable to the highest α value reported previously. Nonvolatile and repeatable magnetization changes in remanent states are also demonstrated. These results will pave the way for room-temperature electric-field control of the magnetization of half-metallic Heusler alloys in high-performance spintronic devices.T. Usami, S. Fujii, S. Yamada, Y. Shiratsuchi, R. Nakatani, and K. Hamaya, Appl. Phys. Lett. 118, 142402 (2021); https://doi.org/10.1063/5.004409

Significant effect of interfacial spin moments in ferromagnet-semiconductor heterojunctions on spin transport in a semiconductor

Using controlled ferromagnet (FM) -semiconductor (SC) interfaces in SC-based lateral spin-valve (LSV) devices, we experimentally study the effect of interfacial spin moments in FM-SC heterojunctions on spin transport in SC. First-principles calculations predict that the spin moment of FM-SC junctions can be artificially reduced by inserting 3d transition metal V, Cr, or Cu atomic layers between FM and SC. When all-epitaxial FM-SC Schottky-tunnel contacts with a 0.4-0.5-nm-thick V, Cr, or Cu interfacial layer are formed, we find that the spin signals in FM-SC LSV devices are significantly decreased at 8 K. When we increase the interfacial spin moment by inserting an ∼0.3-nm-thick Co layer between FM and SC, the spin signals at 8 K are significantly enhanced again. From these experiments, we conclude that the interfacial spin moments at FM-SC interfaces are one of the important factors to achieve large spin signals even in SC-based spintronic devices.T. Naito, R. Nishimura, M. Yamada, A. Masago, Y. Shiratsuchi, Y. Wagatsuma, K. Sawano, R. Nakatani, T. Oguchi, and K. Hamaya, Significant effect of interfacial spin moments in ferromagnet-semiconductor heterojunctions on spin transport in a semiconductor, Phys. Rev. B 105, 195308

Variabilidade espacial da resistência à penetração no perfil do solo sob semeadura direta e preparo convencional.

bitstream/CPAC-2010/30249/1/bolpd-208.pd

Spatial Distribution of Dung in Integrated Dairy Systems

Animals in grazing work as catalyst in the nutrient cycling processes of the ecosystems. Part of biomass that animal intake returning to soil in the degraded way like faeces and urine. The return is around 90% of the mineral nutrients, including nitrogen. However, it is necessary to know how these dejects are distributed on the area by animals. The environment management affects directly spatial distribution of these dejects. Drinking fountain, salt and feed trough, portress, rest area and shadow are structures that change the way that animal graze. Sward structure and herbage morphology affect the grazing behaviour as well. So, the objective this experiment was evaluate the spatial distribution of dung from dairy heifers in integrated systems of production at Mato Grosso, Brazil. The experiment was accomplished at Embrapa (Sinop/Mato Grosso/ Brazil). The experimental area was 10 ha divided in three systems: full sun, marginal shadowing (300 trees per ha) and intensive shadowing (750 trees per ha). Each system had different sizes, but 2.4 ha was useful area for all systems divided in 10 paddocks each. The tree used was Eucalyptus urograndis, H13 clone and the pasture was piata Grass (Urochloa brizantha). The grazing was done when the sward reached 95% light interception. It was evaluated a group of 24 breed heifers with 350 kg in three periods of year. Each paddock was divided in 25 grids for count of faeces boards. The spatial faeces distribution was evaluated with GPS, by walking and capturing points where there was faeces boards in all steps for the grassland paddocks, in three periods of year (rainy, rainy-drought transition and dry period). The dataset was analysed by SAS 9.2 version, using PROC MIXED and PDIFF to 5% of significance. The spatial distribution of dung had significant difference only in rainy-drought transition period (P=0.0165) and interaction effect between shadowing and site (P=0.0025) in this period of year and dry period as well (P=0. 0465). In both periods, the distribution was the same. The full sun system promoted more concentration of faeces boards in sites next portress and border fence in site opposite to portress. In marginal shadowing system, the major concentration was in the central area and under shadow. In intensive shadowing system, the major concentration of dung boards was under shadow, sites preferred by heifers for rumination and leisure activities. The kind of shade and the year periods affected in spatial dung distribution. There were places with more dung concentration, in all kind of shade, but when the pasture had the intensive shade, the dispersion was more homogeneous. Unlike expected, the dung deposition didn?t happens only under treetops. The distribution is more homogeneous when trees are in large quantities. The shadow area available in the grassland affected the spatial dung distribution, and can be more homogeneous than no shadow

Overexpression of the p53-inducible brain-specific angiogenesis inhibitor 1 suppresses efficiently tumour angiogenesis

The brain-specific angiogenesis inhibitor 1 gene has been isolated in an attempt to find fragments with p53 “functional” binding sites. As reported herein and by others, brain-specific angiogenesis inhibitor 1 expression is present in some normal tissues, but is reduced or lost in tumour tissues. Such data and its particular structure prompted the hypothesis that brain-specific angiogenesis inhibitor 1 may act as a mediator in the local angiogenesis balance. We herein demonstrate that brain-specific angiogenesis inhibitor 1 over-expression suppresses tumour angiogenesis, delaying significantly the human tumour growth in immunodeficient mice. The inhibitory effect of brain-specific angiogenesis inhibitor 1 was documented using our intravital microscopy system, strongly implicating brain-specific angiogenesis inhibitor 1 as a mediator in the control of tumour angiogenesis. In contrast, in vitro tumour cell proliferation was not inhibited by brain-specific angiogenesis inhibitor 1 transfection, whereas some level of cytotoxicity was assessed for endothelial cells. Immunohistochemical analysis of tumour samples confirmed a reduction in the microvessel density index in brain-specific angiogenesis inhibitor 1-overexpressing tumours. At messenger level, moderate changes could be detected, involving the down-regulation of vascular endothelial growth factor and collagenase-1 expression. Furthermore, brain-specific angiogenesis inhibitor 1 expression that was lost in a selection of human cancer cell lines could be restored by wild-type p53 adenoviral transfection. Brain-specific angiogenesis inhibitor 1 should be considered for gene therapy and development of efficient drugs based on endogenous antiangiogenic molecules

Improved grazing activity of dairy heifers in shaded tropical grasslands.

Trees in the production systems can effectively reduce hot weather-induced stress in the Brazilian Midwest. High temperatures cause changes in animals daily routine, and trees into pastures can promote benefits. The aim of this research was to evaluate the behavior of dairy heifers in silvopastoral systems in the state of Mato Grosso, Brazil. A herd of 24 crossbreed heifers (3/4 and 7/8 Holstein/Zebu), 350kg average weight, was evaluated over three seasons. Piatã grass was managed under three shade levels: full-sun, moderate-shade, and intensive-shade provided by 10 to 12m high Eucalyptus trees. Behavior data were collected every 15 minutes from 8:30h to 16h. Shade availability significantly impacted heifer behavior, mainly affecting grazing frequency and time during the hottest hours. Grazing behavior was affected by shade levels during the different seasons. Heifers showed preferred grazing times. Heifers in the intensive-shade system visited shady areas during the hottest hours throughout the seasons. Heifers in the full sun-system avoided grazing during the warmer times, ceasing feeding activities. Our results from the Brazilian Midwest showed that shade availability causes breed heifers to change their daily routine