Santos R.F.S.,Federal University of Pernambuco |
Andrade C.A.S.,Federal University of Pernambuco |
Dos Santos C.G.,Institute Educacao |
De Melo C.P.,Federal University of Pernambuco
Journal of Nanoparticle Research | Year: 2013
We describe the use of solution chemistry methods to prepare polyaniline/(gold nanoparticles) - PANI/AuNPs - composites as colloidal particles that exhibit an intense green fluorescence after excitation in the ultraviolet region. Measurements of the relative fluorescence quantum yield indicate that the intensity of the observed luminescence of these nanocomposites is a few orders of magnitude higher than the corresponding fluorescence of either the isolated polymer or the pure AuNPs. Hence, cooperative effects between the conducting polymer chains and the metallic particles must dominate the emission behavior of these materials. Transmission electron microscopy reveals the existence of metal nanoparticle aggregates with sizes in the 2-3 nm range dispersed in the polymer matrix. By implementing an experimental planning, we have been able to change the preparation parameters so as to vary in a controlled manner the intensity and the profile of the luminescence spectrum as well as the size and aggregation characteristics of the colloidal particles. We also show that when the pH of the medium is varied, the dielectric properties (such as the degree of conductivity) of the PANI/AuNPs colloidal solutions and the intensity of their luminescence change in a consistent manner. Due to the polycation nature of the doped PANI chains, we suggest that these composites may find interesting applications as fluorescent markers of biologic molecules. © 2013 Springer Science+Business Media Dordrecht.
PubMed | Institute Pesquisa Clinica Evandro Chagas, Institute Educacao, Federal University of Rio de Janeiro and Grande Rio University
Type: | Journal: Materials science & engineering. C, Materials for biological applications | Year: 2015
The aim of this work was to develop and characterize nanoparticles as carriers of lapazine, a phenazine derived from -lapachone; its antimycobacterial activity is described for the first time as a potential treatment for tuberculosis. The lapazine was synthesized, and by using gas chromatography coupled to a flame ionization detector, it was possible to evaluate its purity degree of almost 100%. For better elucidation of the molecular structure, mass spectroscopy and 1H NMR were carried out and compared to the literature values. Lapazine was assayed in vitro against H37Rv Mycobacterium tuberculosis and a rifampicin-resistant strain, with minimum inhibitory concentration values of 3.00 and 1.56 g mL(-1), respectively. The nanoparticles showed a polydispersity index of 0.16,mean diameter of 188.5 1.7 mm, zeta potential of -15.03 mV, and drug loading of 54.71 mg g(-1) for poly--caprolactone (PCL) nanoparticles and a polydispersity index of 0.318,mean diameter of 197.4 2.7 mm, zeta potential of -13.43 mV and drug loading of 137.07 mg g(-1) for poly(DL-lactide-co-glycolide) (PLGA) nanoparticles. These results indicate that both polymeric formulations have good characteristics as potential lapazine carriers in the treatment of tuberculosis.
PubMed | Grande Rio University and Institute Educacao
Type: Journal Article | Journal: Historia, ciencias, saude--Manguinhos | Year: 2015
The aims of the study are to look at methods and strategies used for analyzing people and classifying them as homosexual and to discuss how certain mechanisms which have been established have made it possible to look at their bodies and arrive at conclusions with regard to such persons. We analyze articles from Science Direct, using a Foucaultian approach. We observe the operation of two technologies: medical body imaging techniques and examinations. These techniques transform the individuals into parts of a strategic device which can be used to build up knowledge, produce files and data, and classify the subjects. The development of this research makes it possible for us to identify certain relationships between homosexuality, the production of scientific knowledge, prejudice, politics and health.
Martins A.C.V.,Federal University of Ceará |
De Lima-Neto P.,Federal University of Ceará |
Barroso-Neto I.L.,Federal University of Ceará |
Cavada B.S.,Federal University of Ceará |
And 2 more authors.
RSC Advances | Year: 2013
We report quantum biochemistry calculations focusing on the binding pocket of the glutamate receptor co-crystallized with agonists (full and partial) and a antagonist. The calculated electronic binding energy follows the order AMPA > glutamate > kainate > DNQX, which explains published experimental data on GluR2 activation and antagonism strength. © The Royal Society of Chemistry 2013.
Meira M.,Institute Educacao |
Quintella C.M.,Federal University of Bahia |
Ribeiro E.M.O.,Federal University of Bahia |
Silva H.R.G.,Federal University of Bahia |
Guimaraes A.K.,Federal University of Bahia
Biomass Conversion and Biorefinery | Year: 2015
This paper presents an overview of the main challenges in the production of biodiesel. Whereas the cost of biodiesel is determined for about 85 % by the cost of the raw material and that the most employed feedstock are oils used also for nutrition, it seems obvious that it is necessary to search for nonedible feedstock with low cost for the production of biodiesel. The choice of feedstock is based on variables such as the oil yield, local availability, cost, and government support. Feedstocks with higher oil yields are more preferable in the biodiesel industry because they can reduce the production cost. In Brazil, approximately 80 % of the biodiesel produced is made from soybean despite of its low oil content (18–21 %). The leadership of soybeans as feedstock for biodiesel production is explained by the increasing demand for more protein meal. Coconut and babassu with more oil yield respectively with 62 and 60 % of oil content are likely substitutes for soybean. Castor bean, despite of its high oil content (50 %) and advantages, such as low production cost and its resistance to hydric stress, has some difficulties to meet the ANP regulations, mainly due to its high viscosity. However, castor bean biodiesel-diesel blends of up to 40 % are within specifications. Yield per hectare is another factor that should be considered in the choice of raw material for the production of biodiesel. Among the various oilseeds, oil palm deserves to be highlighted as the most productive. © 2014, Springer-Verlag Berlin Heidelberg.
Costa S.N.,Federal University of Ceará |
Sales F.A.M.,Federal University of Ceará |
Freire V.N.,Federal University of Ceará |
Maia F.F.,Rural University |
And 4 more authors.
Crystal Growth and Design | Year: 2013
The X-ray diffraction data of l-serine anhydrous crystals was taken into account to initialize the total energy minimization process of their unit cell through density functional theory (DFT) computations, which were performed within both the local density and generalized gradient approximations with dispersion, LDA, and GGA+D, respectively. The calculated lattice parameters are in good agreement with the experimental results for the dispersion corrected generalized gradient approximation functional, with a unit cell volume larger by only about 0.32%; the Mulliken and Hirschfield charges show the zwitterionic state of the l-serine molecules in the DFT converged crystals. The electronic (band structure, density of states) and optical absorption properties were calculated to explain the light absorption of the l-serine anhydrous crystalline powder we have measured at room temperature. The optical absorption related to transitions between the top of the valence band and the bottom of the conduction band involves O-2p valence states and H-1s conduction states. The LDA (4.74 eV) and GGA+D (4.75 eV) estimated energy gaps are about 1 eV below the estimated value from optical absorption measurements (5.90 eV). Small values were obtained for the electron effective masses, which are almost isotropic, whereas large anisotropic values were found for hole effective masses, suggesting that the l-serine anhydrous crystal behaves like an n-type wide gap semiconductor. Different dielectric function profiles obtained for some of the most important symmetry directions also demonstrate the optical anisotropy of l-serine anhydrous crystals. © 2013 American Chemical Society.
Schmidt F.,Institute Educacao |
Fortes M.A.,Federal University of Pelotas |
Wesz J.,Federal University of Pelotas |
Buss G.L.,Federal University of Pelotas |
de Sousa R.O.,Federal University of Pelotas
Revista Brasileira de Ciencia do Solo | Year: 2013
Iron toxicity is recognized as the most widely distributed nutritional disorder in flooded and irrigated rice (Oryza sativa L.), derived from the excessive amounts of ferrous ions (Fe2+) generated by the reduction of iron oxides. The effects of water management on the redox potential of a flooded Albaqualf soil and on iron toxicity symptoms in rice were evaluated in a greenhouse experiment. Treatments were arranged in a randomized complete block design with four replications, and consisted of five water management: T1 - Beginning of flooding in the stage V2-V3; T2 - Beginning of flooding in the stage V6-V7; T3 - as T1 and drainage in the stage V10-V11; T4 - T2 and drainage in the stage V10-V11; and T5 - T1 and drainages in the stage V7-V8 and V10-V11. The delay of flooding until V6-V7 maintained a higher potential of the soil resulting in less available Fe and shifting the maximum Fe release in soil solution to later stages of rice growth. Draining throughout the rice vegetative growth promoted soil re-oxidation, which increase the redox potential and decrease Fe concentration in the soil solution. The use of repeated drainages during the vegetative growth was efficient to control Fe toxicity in rice grown in flooded soil.
De Freitas D.B.,Institute Educacao |
De Freitas D.B.,Federal University of Rio Grande do Norte |
De Medeiros J.R.,Federal University of Rio Grande do Norte
EPL | Year: 2012
In the present study, we analyze the radial-velocity distribution as a function of different stellar parameters such as stellar age, mass, rotational velocity and distance to the Sun for a sample of 6781 single low-mass field dwarf stars, located in the solar neighborhood. We show that the radial-velocity distributions are best fitted by q-Gaussians that arise within the Tsallis nonextensive statistics. The obtained distributions cannot be described by the standard Gaussian that emerges within Boltzmann-Gibbs (B-G) statistical mechanics. The results point to the existence of a hierarchical structure in phase space, in contrast to the uniformly occupied phase space of B-G statistical mechanics, driven by the q-Central Limit Theorem, consistent with nonextensive statistical mechanics. © Europhysics Letters Association.
de Oliveira I.A.,São Paulo State University |
Campos M.C.C.,Institute Educacao |
Soares M.D.R.,Federal University of Acre |
de Aquino R.E.,São Paulo State University |
And 2 more authors.
Revista Brasileira de Ciencia do Solo | Year: 2013
Considering the importance of knowledge of the spatial distribution of soil properties, the purpose of this study was to evaluate the spatial variability of physical properties in a Cambisolunder different land uses in the southern Amazon region. The study was conducted on three farms with cassava, sugarcane, and agroforestry, in the region of Humaitá, in the south of the State of Amazonas. In these areas, 70 x 70 m grids were established, with a regular spacing of 10 x 10 m and a total of 64 points, where soils were sampled at 0.0-0.10 m depth. Texture (sand, silt, and clay), macroporosity, microporosity, total porosity, bulk density, and aggregate stabilitywere determined. The data were analyzed using descriptive statistics and geostatistics. It was found that the propertiesvaried spatially and that the range of these variations between land uses was different, with the highest variability for the sugarcane management.
Sabaini D.S.,Institute Educacao |
Casagrande L.P.,Institute Educacao |
de Barros A.F.,Mato Grosso State University
Boletim do Instituto de Pesca | Year: 2015
Farmers and entrepreneurs in the northern region of the Brazil have shown interest in investing on the cultivation of the Amazon spotted catfish (Pseudoplatystoma spp.) in a system of net cages. However, the lack of information regarding the activity limits its development. Therefore, the objective of this study was to determine investment and startup costs and technical and economic feasibility of the cultivation of this species in cages system in the state of Rondônia. The study determined the theoretical total production cost per kilogram of fish, for implementing 50 cages of 18 m3. To obtain the average total cost of kilogram of fish production was used the methodology of the total cost of production. Based on technical data obtained directly from the productive sector, were used juveniles with an initial average weight 0.1 kg, reaching a final stocking biomass of 42 kg m-3, survival rate of 95%, feed conversion of 1.98, a final average weight of 3.0 kg and a growth period of 12 months. The cage system production demonstrated economic feasibility, with a total investment of R$ 182,201.20. The average total cost of producing 33,949 kg of fish was R$ 7.27 kg-1, the average sales price was of R$ 7.38 kg-1 and a net profit of R$ 3,655.92 per year. The period of return on capital was of 3.15 years and internal return index of 19.04%, over project’s horizon of six years. © 2015, Instytut Technologii Drewna. All rights reserved.