Federal University of Roraima

About: Federal University of Roraima is a based out in . It is known for research contribution in the topics: Population & Thermogravimetry. The organization has 981 authors who have published 1218 publications receiving 7849 citations. The organization is also known as: Federal University of Roraima.

Inoculação de Bradyrhizobium em soja por pulverização em cobertura

Abstract: The objective of this work was to evaluate a Bradyrhizobium inoculation method on soybean by spraying inoculant over plants. An experiment was conducted in the Cerrado of Roraima. Treatments tested were: control without inoculation; standard inoculation method with two doses of inoculant per hectare applied on seeds; inoculation with threefold standard inoculation dose applied 18 days after plants emergence (DAE); fertilization with 200 kg ha-1 of nitrogen, without inoculation. The inoculation by spraying on covering increased nodulation and plant dry matter in the 45 and 60 DAE. It also increased significantly grain yield and N content, similarly to N fertilization treatment, and was superior to the control, and inferior to the standard inoculation related to grain yield.

Dynamics of the formation of carbon nanotube serpentines.

Abstract: Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] reported the experimental realization of carbon nanotube S-like shaped nanostructures, the so-called carbon nanotube serpentines. We report here results from multimillion fully atomistic molecular dynamics simulations of their formation. We consider one-� m-long carbon nanotubes placed on stepped substrates with and without a catalyst nanoparticle on the top free end of the tube. A force is applied to the upper part of the tube during a short period of time and turned off; then the system is set free to evolve in time. Our results show that these conditions are sufficient to form robust serpentines and validates the general features of the ‘‘falling spaghetti model’’ proposed to explain their formation.

Synthesis, characterization, solid state and aqueous solution fluorescence study for lanthanide-crown ether-terpyridine complexes

Abstract: The complexes [Eu(12-crown-4)(terpy)(H2O)]3Cl, [Eu(15-crown-5)(terpy)]3Cl, [Tb(12-crown-4)(terpy)(H2O)]3Cl, [Tb(15-crown-5)(terpy)]3Cl, [Gd(12-crown-4)(terpy)(H2O)]3Cl and [Gd(15-crown-5)(terpy)]3Cl (terpy = 2,2′,6′,2′′-terpyridine) were synthesized and characterized by CHN elemental analysis, infrared spectroscopy and fluorescence spectroscopy. Emission spectra were obtained on both, solid state and aqueous solutions for europium and terbium complexes. The complexes exhibit good emission, even in aqueous solution, enhancing their potential for biological applications. The reduction of emission intensity, from solid state to aqueous solution, is lower for europium complexes, in comparison to terbium complexes. The [Eu(12-crown-4)(terpy)(H2O)] · 3Cl complex exhibits an emission lifetime of 0.64 ms while [Eu(15-crown-5)(terpy)] · 3Cl exhibits a value of 0.38 ms. Furthermore, the 15-crown-5 complex emission intensity is about 3.8 times larger than the emission intensity of the 12-crown-4 complex. This ratio ...