631 research outputs found

    Short-range Charge and Spin Superstructures in Doped Layered Co Perovskites

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    We have investigated cobaltite relatives of the layered perovskite cuprates and nickelates, Pr2x_{2-x}Cax_xCoO4_4 (0.39x0.730.39 \leq x \leq 0.73) and La2x_{2-x}Srx_xCoO4_4 (x=0.61x = 0.61), using elastic neutron scattering. We have discovered doping-dependent incommensurate short-range ordering of charges and magnetic moments, which in cobaltites occur in the range of heavy doping, 0.5x0.75 0.5 \lesssim x \lesssim 0.75. The charge order exists already at room temperature and shows no change on cooling. The incommensurability of its propagation vector, Qc=(ϵc,0,l){\bf Q}_c = (\epsilon_c,0,l), roughly scales with the concentration of Co2+^{2+} ions, ϵc(1x)\epsilon_c \sim (1-x). Magnetic order is only established at low T40\lesssim 40 K and has twice larger periodicity, indicating a dominant antiferromagnetic correlation between the nearest Co2+^{2+} spins.Comment: 4 pages 4 figure

    Plant breeding with marker-assisted selection in Brazil.

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    Over the past three decades, molecular marker studies reachedextraordinary advances, especially for sequencing and bioinformatics techniques.Marker-assisted selectionbecamepart of the breeding program routines of important seed companies, in order to accelerate and optimize the cultivar developing processes. Private seed companies increasingly use marker-assisted selection, especially for the species of great importance to the seed market, e.g. corn, soybean, cotton, and sunflower. In the Brazilian public institutions few breeding programs use it efficiently.The possible reasons are: lack of know-how, lack of appropriate laboratories, few validated markers, high cost, and lack of urgency in obtaining cultivars. In this article we analyze the use and the constraints of marker-assisted selection in plant breeding programs of Brazilian public institute

    BMP12 induces tenogenic differentiation of adipose-derived stromal cells

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    <div><p>Adipose-derived stromal cells (ASCs) are pluripotent cells that have the capacity to differentiate into tendon fibroblasts (TFs). They are abundant in adults, easy to access, and are therefore an ideal cell source for tendon tissue engineering. Despite this potential, the molecular cues necessary for tenogenic differentiation of ASCs are unknown. Unlike other bone morphogenetic proteins (BMPs), BMP12, BMP13, and BMP14 have been reported to be less osteo-chondrogenic and to induce tendon rather than bone formation <i>in vivo</i>. This study investigated the effects of BMP12 and BMP14 on ASC differentiation <i>in vitro</i>. In canine ASCs, BMP12 effectively increased the expression of the tendon markers scleraxis and tenomodulin at both mRNA and protein levels. Consistent with these results, BMP12 induced scleraxis promoter driven-GFP and tenomodulin protein expression in mouse ASCs. Although BMP12 also enhanced the expression of the cartilage matrix gene aggrecan in ASCs, the resulting levels remained considerably lower than those detected in tendon fibroblasts. In addition, BMP12 reduced expression of the bone marker osteocalcin, but not the osteogenic transcription factor runx-2. BMP14 exhibited similar, but marginally less potent and selective effects, compared to BMP12. BMPs are known to signal through the canonical Smad pathway and the non-canonical mitogen-activated protein kinase (MAPK) pathway. BMP12 triggered robust phosphorylation of Smad1/5/8 but not Smad2/3 or p38 MAPK in ASCs. The effect was likely conveyed by type I receptors ALK2/3/6, as phosphorylation of Smad1/5/8 was blocked by the ALK2/3/6 inhibitor LDN-193189 but not by the ALK4/5/7 inhibitor SB-505124. Moreover, ALK6 was found to be the most abundant type I receptor in ASCs, with mRNA expression 100 to 10,000 times that of any other type I receptor. Collectively, results support the conclusion that BMP12 induces tenogenic differentiation of ASCs via the Smad1/5/8 pathway.</p> </div

    Intercalação de leguminosas herbáceas perenes no manejo de plantas daninhas do cafezal no Cerrado.

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    O manejo sustentável dos sistemas de produção do café no Cerrado para minimizar os impactos ambientais, requer práticas alternativas, devido os espaçamentos largos das lavouras, que permite a ampla utilização de insumos químicos e de máquinas agrícolas. A cobertura viva com leguminosas perenes proporciona melhorias das condições do solo e redução da infestação de plantas daninhas com menores custos pela diminuição de aplicação de fertilizantes nitrogenados e de herbicidas. O objetivo deste trabalho foi de avaliar a influência de leguminosas herbáceas perenes no manejo das plantas daninhas e na cultura do café do cerrado
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