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Search Results: 1 - 10 of 294305 matches for " E. H. Alcantara "
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On the water thermal response to the passage of cold fronts: initial results for Itumbiara reservoir (Brazil)
E. H. Alcantara,M. P. Bonnet,A. T. Assireu,J. L. Stech
Hydrology and Earth System Sciences Discussions , 2010, DOI: 10.5194/hessd-7-9437-2010
Abstract: The passage of meteorological systems such as cold fronts or convergence zones over reservoirs can cause significant modifications in several aquatic variables. Cold fronts coming from higher latitudes and reaching the Southeastern Brazilian territory modify the mean wind field and have important impact over physical, chemical and biological processes that act in the hydroelectric reservoirs. The mean period of cold front passages along the Southeastern Brazilian coast is 6 days during the winter and between 11 and 14 days in the summer. Most of these fronts also affect the hinterland of S o Paulo, Minas Gerais and Goiás states. The objective of this work is to analyze the influence of cold front passages in the thermal stratification and water quality of the Itumbiara hydroelectric reservoir which is located in Minas Gerais and Goiás. The characterization of cold front passages over the study area was done through the analysis of GOES satellite images. The analyzed data set includes time series of meteorological (wind direction and intensity, short-wave radiation, air temperature, relative humidity, atmospheric pressure) and water temperature in four depths (5, 12, 20 and 40 m). The data set was acquired in the interior of the reservoir by an autonomous anchored buoy system at a sampling rate of 1 h. The stratification was assessed by non-dimensional parameter analysis. The lake number an indicator of the degree of stability and mixing in the reservoir was used in this analysis. We will show that during the cold front all atmospheric parameters respond and this response are transferred immediately to the water surface. The main effect is observed in the water column, when the heat loss in the surface allows the upwelling events caused by convective cooling due to the erosion of thermal stratification.
Electrodialysis of Phosphates in Industrial-Grade Phosphoric Acid
J. J. Machorro,J. C. Olvera,A. Larios,H. M. Hernández-Hernández,M. E. Alcantara-Gardu?o,G. Orozco
ISRN Electrochemistry , 2013, DOI: 10.1155/2013/865727
Abstract: The objective of this research was to study the purification of industrial-grade phosphoric acid (P2O5) by conventional electrodialysis. The experiments were conducted using a three-compartment cell with anion and cation membranes, and industrial acid solution was introduced into the central compartment. The elemental analysis of the diluted solution indicated that the composition of magnesium, phosphates, and sodium was reduced in the central compartment. The ratios of the concentration of the ions and the phosphates were essentially unchanged by the process. Consequently, electrodialysis could not purify the acid in the central compartment, and the migration of phosphate ions to the anolyte produced a highly concentrated phosphoric acid solution containing sulfates and chlorides as impurities. However, the migration of the phosphate ions across the membrane consumed a large amount of energy. Detailed speciation diagrams were constructed in this study. These diagrams showed that metal-phosphate complexes were predominant in the industrial phosphoric acid solution. This result explains why the ratios of the concentrations of the ion metals and the phosphates did not change in the purification process. The energy consumed in the electrodialysis indicated that the metal-phosphate complexes were less mobile than the free-phosphate ions. The speciation diagrams explained the experimental results satisfactorily. 1. Introduction The annual global phosphorus consumption is approximately 20,764 million metric tons [1]. Phosphoric acid and phosphate salts have several applications. For example, phosphoric acid fuel cells use liquid phosphoric acid as an electrolyte [2, 3]. Industrial-grade phosphoric acid is produced from phosphate rock and consequently has a high content of mineral impurities, which lower the acid quality for commercial use. This industrial-grade phosphoric acid (52–54% P2O5) is also named as merchant-grade acid. Phosphoric acid purification is a major challenge, and a variety of methods have been used to eliminate the impurities in the industrial-grade phosphoric acid [4–18]. These methods which are described in the literature are enumerated in Table 1. In addition, Table 2 shows electrodialysis process for concentrating industrial-grade phosphoric acid [19–27]. These studies in Table 2 provided more comprehensive and consistent information on the energy requirements for the process. Comparing these methods is very difficult for the following reasons: (a) there is a wide variation in the types of the impurities in industrial-grade acid because
Accessing the Potential of Satellite and Telemetric Data to Evaluate the Influence of the Heat Flux Exchange in the Water Column Mixing and Stratification  [PDF]
Enner Alcantara
International Journal of Geosciences (IJG) , 2012, DOI: 10.4236/ijg.2012.325092
Abstract: The objective of this work is to evaluate the feasibility of moderate resolution satellite data estimating the surface heat balance in a tropical hydroelectric reservoir. Each component of the heat flux balance was computed using the MODIS (Moderate Resolution Imaging Spectroradiometer) water surface temperature (WST) level 2, 1 km nominal resolution data (MOD11L2, version 5) from 2003 to 2008. The consequence of the heat flux exchange in the water column thermal structure is also investigated. The passage of cold front over a region decreases the atmospheric pressure and air temperature, enhancing the relative humidity. The sensible flux presents a small variability but an increase occurs due to a convective turbulence caused by front passage. The latent flux decrease but insufficiently to cause a condensation, just the evaporation decreases. The upwelling events are the responsible to maintain the loss of heat after the cold front pas- sage.
In-beam gamma ray spectroscopy of 58Co
Silveira, M. A. G.;Medina, N. H.;Oliveira, J. R. B.;Alcantara-Nu?ez, J. A.;Cybulska, E. W.;Dias, H.;Rao, M. N.;Ribas, R. V.;Seale, W. A.;Wiedemann, K. T.;
Brazilian Journal of Physics , 2005, DOI: 10.1590/S0103-97332005000500027
Abstract: the odd-odd 58co nucleus has been studied with the 51v(10b, p2n) reaction at 33-mev incident energy and the g-spectrometer saci-pererê. excited states up to 8.0 mev and spin up to 11+ have been observed. the results are compared to shell model calculations using the gxpf1 effective interaction, developed for use in the fp shell. the pf7/2-1?n(p3/22f5/21) configuration was assigned to the yrast levels.
Twenty years of research on cholesteric lyotropic liquid crystals at the Chemistry Institute of the University of S?o Paulo
Alcantara, M. R.;Fernandes Jr., E. G.;
Brazilian Journal of Physics , 2002, DOI: 10.1590/S0103-97332002000300009
Abstract: in this paper we present a review of twenty years of research on cholesteric liquid crystals at the chemistry institute of the university of s?o paulo. the results on the interaction forces, responsible for the maintenance of the helical structure, are a function of the chemical variability obtained in these systems. the last results obtained using rheological techniques are presented, and research in this field was undertaken in order to understand the cholesterization process when different systems and inductors are involved.
Twenty years of research on cholesteric lyotropic liquid crystals at the Chemistry Institute of the University of S o Paulo
Alcantara M. R.,Fernandes Jr. E. G.
Brazilian Journal of Physics , 2002,
Abstract: In this paper we present a review of twenty years of research on cholesteric liquid crystals at the Chemistry Institute of the University of S o Paulo. The results on the interaction forces, responsible for the maintenance of the helical structure, are a function of the chemical variability obtained in these systems. The last results obtained using rheological techniques are presented, and research in this field was undertaken in order to understand the cholesterization process when different systems and inductors are involved.
Recomendaciones para el diagnóstico y tratamiento del síndrome coronario agudo sin elevación del segmento ST
Civeira Murillo,E.; Nogal Saez,F. Del; álvarez Ruiz,A.P.; Ferrero Zorita,J.; Alcantara,á.G.; Aguado,G.H.; López Messa,J.B.; Montón Rodríguez,J.A.; ,;
Medicina Intensiva , 2010,
Abstract: these recommendations are designed to be of assistance to doctors in icus when making first evaluations of these patients. they are mainly intended to assist with early diagnosis, risk stratification and initial treatment. the need for individualised treatment is at present one of the main objectives in the management of acute coronary syndrome (acs), with or without st elevation, and this is why we believe the recommendations should be of a predominantly practical nature, given that they affect decision making in the day to day practice of medicine.
Horm?nio do crescimento ou somatotrófico: novas perspectivas na deficiência isolada de GH a partir da descri??o da muta??o no gene do receptor do GHRH nos indivíduos da cidade de Itabaianinha, Brasil
Souza, Anita Hermínia O.;Salvatori, Roberto;Martinelli Jr, Carlos E.;Carvalho, Walter M.O.;Menezes, Carlos A.;Barretto, Elenilde S. de A.;Barreto Filho, José A.S.;Alcantara, Marta R.S. de;Oliveira, Carla R.P.;Alcantara, Paula R.S. de;Ramalho, Roberto J.R.;Oliveira, Hélio A.;Lima, Ivana B. de;Carneiro, Jamille N.;Santos, Marcos M.;Gill, Matthew S.;Clayton, Peter E.;Oliveira, Manuel H. A;
Arquivos Brasileiros de Endocrinologia & Metabologia , 2004, DOI: 10.1590/S0004-27302004000300013
Abstract: in addition to stimulating body growth, growth or somatotrophic hormone plays an important role in metabolism, body composition, lipid profile, cardiovascular status and longevity. its control is multiregulated by hormones, metabolites and hypothalamic peptides. obtained data of the isolated growth hormone deficiency (ighd) after the description of the ivs1+1g?a ghrh receptor gene mutation in individuals of itabaianinha county are reviewed. new perspectives about the growth hormone resistance model, the importance of ghrh in the control of gh secretion, the frequency of ghrh-r gene mutations, the diagnostic relevance of igf-i and the metabolic, cardiovascular and quality of life findings are approached.
The turbidity behavior in an Amazon floodplain
E. Alcantara,E. Novo,J. Stech,J. Lorenzzetti
Hydrology and Earth System Sciences Discussions , 2009,
Abstract: The main objective of this study is to understand the turbidity behavior of an Amazon Floodplain Lake. Observations of turbidity provide quantitative information about water quality. However, the number of available in situ measurements for water quality determination is usually limited in time and space. Here, we present an analysis of the temporal and spatial variability using two approaches: (i) the first is based on wavelet analysis of a turbidity time series measured by an automatic monitoring system; (ii) the second is based on turbidity samples measured in different locations and then interpolated by an ordinary kriging algorithm. The space/time turbidity variability is clearly related to the Amazon River flood pulses in the floodplain. When the water level in the floodplain is rising or receding, the exchange between the Amazon River and the floodplain is the major driving force in turbidity variability. At high water level, the turbidity variability is controlled by the lake bathymetry. Finally, when the water level is low, the wind action and lake morphometry are the main causes of turbidity variability. The combined use of temporal and spatial data showed a great potential for understanding the turbidity behavior in a complex aquatic system, like the Amazon floodplain.
Paleoseismology of the southwestern Morelia-Acambay fault system, central México
Gardu?o-Monroy, V. H.;Pérez-Lopez, R;Israde-Alcantara, I;Rodríguez-Pascua, M. A.;Szynkaruk, E;Hernández-Madrigal, V. M.;García-Zepeda, M. L.;Corona-Chávez, P;Ostroumov, M;Medina-Vega, V. H.;García-Estrada, G;Carranza, O;Lopez-Granados, E;Mora Chaparro, J. C.;
Geofísica internacional , 2009,
Abstract: fr the morelia-acambay fault system (mafs) consists of a sequence of e-w and nne-ssw trending normal faults within the trans-mexican volcanic belt. the fault system is associated to the chapala, zacapu, cuitzeo, maravatio and acambay lacustrine depressions. the e-w faults of mafs appear to be 7-9 million yr old while the nnw-sse faults are older and were reactivated producing stepped east-west geometry with a transtensional-right hand deformation. seismic magnitudes of the e-w structures in the morelia-cuitzeo region are estimated. cartography, structural geology, and trench stratigraphy of these faults suggest holocene activity. historical earthquakes disrupted paleosols containing pirinda-purepecha shards. these historical earthquakes are also imprinted in seisms along e-w faults at los azufres geothermal field. in the pátzcuaro region, the e-w structures are also linked to strong seismic events occurred during prehistoric and historical times. the jaracuaro lacustrine sequence in the southern patzcuaro lake contains evidence at least three important earthquakes (postclassic, 1845 and 1858) and a possible tsunami associated to the 1858 event. the magnitude of this earthquake was estimated at ~7.3. an earthquake of this magnitude would damage a density populated area of michoacán state. on october 17, 2007, three small earthquakes were felt in morelia associated to normal e-w fault mechanisms of central camionera fault corroborating the seismic potential of mafs in the tmbv.
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