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.

Effect of Harvest Time and Nitrogen Doses on Cassava Root Yield and Quality

Abstract: Nitrogen is considered the most limiting nutrient for cassava, and N availability can influence the crop cycle, including earlier harvest. The aim of this study was to study the effect of harvest time on the production components of cassava, “Aciolina” cultivar, at different rates of N fertiliser. The experiment was carried out in an area newly incorporated into the productive system in a savannah ecosystem in the northern Amazon. A randomised block experimental design was used in a split [...]

Tayassuidae, cervidae e tapiridae da gruta do urso fóssil, holoceno, parque nacional de ubajara, ceará, brasil

Abstract: TAYASSUIDAE, CERVIDAE, AND TAPIRIDAE FROM THE GRUTA DO URSO FOSSIL (HOLOCENE), UBAJARA NATIONAL PARK, CEARA, BRAZIL. Here are described syncranial and postcranial fragments of the holartic ungulates Tayassu pecari (Link), Tapirus terrestris Linnaeus, Mazama Rafi nesque, Tayassuidae indet., and Cervidae indet., from the Gruta do Urso Fossil, Ubajara National Park, Northwest of the State of Ceara, Brazil. The majority of the material was collected on surface of different levels of the cave, except for specimens from the Sala da Entrada portion of the cave, which were collected in subsurface layers at 0.40 m and 0.50 m. These latter points, dated through the thermoluminescence method, indicated 8,000 and 8,200 years BP, respectively. The presence of T. pecari and T. terrestris suggest a forested environment and a humid climate; whereas Mazama may also inhabit other environments. The scarcity and/or disappearance of T. pecari and T. terrestris in the northern region of the State of Ceara could be related to anthropic reasons associated to climate and environmental changes during the late Quaternary. This seems to be corroborated by the current fauna indicating a semiarid (Caatinga) environment. The presence of Mazama however, suggests that this change has not occurred drastically.

Magnetic nanoparticles coated with polyaniline to stabilize immobilized trypsin

Abstract: It is reported the synthesis of magnetic nanoparticles via the chemical co-precipitation of Fe 3+ ions and their preparation by coating them with polyaniline. The electronic micrograph analysis showed that the mean diameter for the nanoparticles is ∼15 nm. FTIR, powder X-ray diffraction and Mossbauer spectroscopy were used to understand the chemical, crystallographic and 57Fe hyperfine structures for the two samples. The nanoparticles, which exhibited magnetic behavior with relatively high spontaneous magnetization at room temperature, were identified as being mainly formed by maghemite (γFe2O3). The coated magnetic nanoparticles (sample labeled “mPANI”) presented a real ability to bind biological molecules such as trypsin, forming the magnetic enzyme derivative (sample “mPANIG-Trypsin”). The amount of protein and specific activity of the immobilized trypsin were found to be 13±5 μg of protein/mg of mPANI (49.3 % of immobilized protein) and 24.1±0.7 U/mg of immobilized protein, respectively. After 48 days of storage at 4 ∘C, the activity of the immobilized trypsin was found to be 89 % of its initial activity. This simple, fast and low-cost procedure was revealed to be a promising way to prepare mPANI nanoparticles if technological applications addressed to covalently link biomolecules are envisaged. This route yields chemically stable derivatives, which can be easily recovered from the reaction mixture with a magnetic field and recyclable reused.

Influência do estádio de maturação na qualidade físico-química de frutos de umbu (Spondias tuberosa)

Abstract: Harvesting at suitable maturation stages is determinant in maintaining post-harvest quality of umbu fruit. In this sense, the aim of this work was to determine the influence of the maturation stage on the physical-chemical quality of umbu fruits from the brazilian northeast. The experiment was conducted at the Food Technology Laboratory of the Agrarian Sciences Center of the Federal University of Roraima, Boa Vista, Roraima, Brazil. The experimental design was a completely randomized design with ten replicates and one fruit per experimental unit. The treatments consisted of three maturation stages of the fruits: green, once and ripe. The physical characteristics evaluated were: fruit length, fruit diameter, seed mass, bark mass, pulp mass, total mass and pulp yield. The determination of the chemical quality was evaluated: pH, soluble solids content, titratable acidity and soluble solids / titratable acidity ratio. It was concluded that the stages of maturation of umbu fruits exert different response capacities regarding their biometry. Fruits of umbu in the green stage have higher mass and consequently higher yield of pulp. The fruit quality of umbu is not influenced by the different maturation stages of the fruits.