bluuebunny/crossref_metadata_2025 huggingface dataset:
Helium Migration Mechanisms in Polycrystalline Uranium Dioxide
Authors: Martin Guillaume , Desgardin Pierre , Garcia Philippe , Sauvage Thierry , Carlot Gaëlle , Barthe Marie-France
Published: October 2011

This study aims at identifying the release mechanisms of helium in uranium dioxide. Two sets of polycrystalline UO2 sintered samples presenting different microstructures were implanted with 3He ions at concentrations in the region of 0.1 at.%. Changes in helium concentrations were monitored using two Nuclear Reaction Analysis (NRA) techniques based on the 3He(d,α)1H reaction. 3He release is measured in-situ during sample annealing at temperatures ranging between 700°C and 1000°C. Accurate helium depth profiles are generated after each annealing stage. Results that provide data for further understanding helium release mechanisms are discussed. It is found that helium diffusion appears to be enhanced above 900°C in the vicinity of grain boundaries possibly as a result of the presence of defects.
Chlorine Diffusion in Uranium Dioxide : Thermal Effects versus Radiation Enhanced Effects
Authors: Pipon Yves , Toulhoat Nelly , Moncoffre Nathalie , Bererd Nicolas , Jaffrezic Henri , Barthe Marie France , Desgardin Pierre , Raimbault Louis , Scheidegger Andre M. , Carlot Gaelle
Published: October 2011

Chlorine is present as an impurity in the UO2 nuclear fuel. 35Cl is activated into 36Cl by thermal neutron capture. In case of interim storage or deep geological disposal of the spent fuel, this isotope is known to be able to contribute significantly to the instant release fraction because of its mobile behavior and its long half life (around 300000 years). It is therefore important to understand its migration behavior within the fuel rod. During reactor operation, chlorine diffusion can be due to thermally activated processes or can be favoured by irradiation defects induced by fission fragments or alpha decay. In order to decouple both phenomena, we performed two distinct experiments to study the effects of thermal annealing on the behaviour of chlorine on one hand and the effects of the irradiation with fission products on the other hand. During in reactor processes, part of the 36Cl may be displaced from its original position, due to recoil or to collisions with fission products. In order to study the behavior of the displaced chlorine, 37Cl has been implanted into sintered depleted UO2 pellets (mean grain size around 18 μm). The spatial distribution of the implanted and pristine chlorine has been analyzed by SIMS before and after treatment. Thermal annealing of 37Cl implanted UO2 pellets (implantation fluence of 1013 ions.cm−2) show that it is mobile from temperatures as low as 1273 K (Ea=4.3 eV). The irradiation with fission products (Iodine, E=63.5 MeV) performed at 300 and 510 K, shows that the diffusion of chlorine is enhanced and that a thermally activated contribution is preserved (Ea=0.1 eV). The diffusion coefficients measured at 1473 K and under fission product irradiation at 510 K are similar (D = 3.10-14 cm2.s−1). Considering in first approximation that the diffusion length L can be expressed as a function of the diffusion coefficient D and time t by : L=(Dt)1/2, the diffusion distance after 3 years is L=17 μm. It results that there is a great probability for the chlorine contained in the UO2 grains to have reached the grain boundaries after 3 years, in the core of the fuel rod as well as at its periphery. Moreover, diffusion and concentration of chlorine at grain boundaries has been evidenced using SIMS mapping. Our results indicate therefore, that, during reactor operation and after, the majority of 36Cl is likely to have moved to grain boundaries, rim and gap. This fraction might then significantly contribute to the rapid or instant release of chlorine. This could have important consequences for safety assessment.
Computational Investigation of the Formation of Hyperstoichiometric Uranium Dioxide (UO2+x)
Authors: Skomurski Frances , Becker Udo , Ewing Rodney
Published: October 2011

The stability of spent nuclear fuel as a waste form largely depends upon the oxidation behavior of uranium dioxide (UO2) under repository conditions. Because U6+ phases are more soluble than U4+ phases, and changes in oxidation state can lead to volume changes which increase the susceptibility of spent fuel to corrosion, understanding the mechanisms behind the formation of more highly oxidized UO2 phases is important. While a variety of diffraction and spectroscopic studies have been used to investigate the oxidation behavior of UO2 to U4O9, questions still remain as to the effect of interstitial oxygen on the oxidation state of uranium in hyperstoichiometric UO2. In this study, computational techniques were used to investigate questions such as: Is the formation of U5+ or U6+ more energetically favorable upon the oxidation of UO2

A density functional theory (DFT) approach was used to investigate energetically favorable locations of interstitial oxygen atoms and to determine their effect on the charge distribution of uranium in U4O9, specifically. A single unit cell of U4O9 is used as a starting model, and the optimized geometry and charge distribution is tested by using starting models with different U charge assignments. Results from our calculations suggest that the formation of one U5+ per addition of interstitial oxygen at a perpendicular bisector site is favorable. Deflection of two lattice oxygen atoms along the body diagonal of the cubic sites is also observed upon the addition of one interstitial oxygen atom. Structural and bond length data are compared with experimental data whenever possible.
A Science-Based Approach to Understanding Waste Form Durability in Open and Closed Nuclear Fuel Cycles
Authors: Peters M. T. , Ewing R. C.
Published: October 2011

There are two compelling reasons for understanding source term and near-field processes in a radioactive waste geologic repository. First, almost all of the radioactivity is initially in the waste form, mainly in the spent nuclear fuel (SNF) or nuclear waste glass. Second, over long periods, after the engineered barriers are degraded, the waste form is a primary control on the release of radioactivity. Thus, it is essential to know the physical and chemical state of the waste form after hundreds of thousands of years. The United States Department of Energy's Yucca Mountain Repository Program has initiated a long-term program to develop a basic understanding of the fundamental mechanisms of radionuclide release and a quantification of the release as repository conditions evolve over time. Specifically, the research program addresses four critical areas: a) SNF dissolution mechanisms and rates; b) formation and properties of U6+-secondary phases; c) waste form–waste package interactions in the near-field; and d) integration of in-package chemical and physical processes. The ultimate goal is to integrate the scientific results into a larger scale model of source term and near-field processes. This integrated model will be used to provide a basis for understanding the behavior of the source term over long time periods (greater than 105 years). Such a fundamental and integrated experimental and modeling approach to source term processes can also be readily applied to development of advanced waste forms as part of a closed nuclear fuel cycle. Specifically, a fundamental understanding of candidate waste form materials stability in high temperature/high radiation environments and near-field geochemical/hydrologic processes could enable development of advanced waste forms “tailored” to specific geologic settings.
Comparative Study on the Corrosion Resistance of Fe-Based Amorphous Metal, Borated Stainless Steel and Ni-Cr-Mo-Gd Alloy
Authors: Lian Tiangan , Day Daniel , Hailey Phillip , Choi Jor-Shan , Farmer Joseph
Published: October 2011

Iron-based amorphous alloy Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 was compared to borated stainless steel and Ni-Cr-Mo-Gd alloy on their corrosion resistance in various high-[Cl-] solutions. The melt-spun ribbon of this iron-based amorphous alloy have demonstrated a better corrosion resistance than the bulk borated stainless steel and the bulk Ni-Cr-Mo-Gd alloy, in high-[Cl-] brines at temperatures 90ºC or higher.
Oxide Film Aging on Alloy 22 in Halide Containing Solutions
Authors: Rodríguez Martín A. , Rebak Raúl B. , Carranza Ricardo M.
Published: October 2011

Passive and corrosion behaviors of Alloy 22 in chloride and fluoride containing solutions, changing the heat treatment of the alloy, the halide concentration and the pH of the solutions at 90°C, was investigated. The study was implemented using electrochemical techniques, which included open circuit potential monitoring over time, potentiodynamic polarization and electro-chemical impedance spectroscopy (EIS) measurements carried out at open circuit and at passiv-ity potentials. Corrosion rates obtained by EIS measurements after 24 h immersion in naturally aerated solutions were below 0.5 m/year. The corrosion rates were practically independent of solution pH, alloy heat treatment and halide ion nature and concentration. EIS low frequency resistance values increased with applied potential in the passive domain and with polarization time in pH 6 - 1M NaCl at 90ºC. This effect was attributed to an increase in the oxide film thick-ness and oxide film aging. High frequency capacitance measurements indicated that passive ox-ide on Alloy 22 presented a double n-type/p-type semiconductor behavior in the passive potential range.
Evolution of Chemistry and Its Effects on the Corrosion of Engineered Barrier Materials
Authors: Dunn Darrell , Pan Yi-Ming , He Xihua , Yang Lietai , Pabalan Roberto
Published: October 2011

The evolution of environmental conditions within the emplacement drifts of a potential high-level waste repository at Yucca Mountain, Nevada, may be influenced by several factors, including the temperature and relative humidity within the emplacement drifts and the composition of seepage water. The performance of the waste package and the drip shield may be affected by the evolution of the environmental conditions within the emplacement drifts. In this study, tests evaluated the evolution of environmental conditions on the waste package surfaces and in the surrounding host rock. The tests were designed to (i) simulate the conditions expected within the emplacement drifts; (ii) measure the changes in near-field chemistry; and (iii) determine environmental influence on the performance of the engineered barrier materials. Results of tests conducted in this study indicate the composition of salt deposits was consistent with the initial dilute water chemistry. Salts and possibly concentrated calcium chloride brines may be more aggressive than either neutral or alkaline brines.
Radiation Tolerance of A2Ti2O7 Materials - A Question of Bonding?
Authors: Whittle Karl , Lumpkin Gregory R , Smith Katherine L , Blackford Mark G , Harvey Elizabeth J , Zaluzec Nestor J
Published: October 2011

The resistance of Ln2Ti2O7 (Ln=lanthanide) compounds to radiation damage is an important topic in the understanding and development of new materials by which radioactive nuclear waste can safely be immobilised. A model has been developed, from previously published density functional theory and molecular orbital theory simulations of the band structure for Ln2Ti2O7 materials. This model provides a chemical interpretation of radiation stability.
Kinetic and Thermodynamic Study of the Chemistry of Neoformed Phases during the Dissolution of Phosphate Based Ceramics
Authors: du Fou de Kerdaniel Erwan , Clavier Nicolas , Dacheux Nicolas , Podor Renaud
Published: October 2011

Phosphate matrices are considered as potential candidates for the specific immobilization of tri- and tetravalent actinides. One of the main properties of interest of these matrices concerns their chemical durability. It was studied through their behavior regarding to the retention of actinides and developped using under- and over-saturation experiments. In this field, neoformed phases were precipitated. Lanthanides were used as surrogates for trivalent actinides while uranium and thorium were used for tetravalent actinides. These phases were extensively characterized through several analytical and spectroscopic techniques (SEM, EPMA, XRD, µ - Raman, TRLFS…).

New phosphate form such as Nd1-2xCaxThx-yUy(PO4,F). ½ H2O rhabdophane were identified during the dissolution of britholites. The precipitation of Nd1-2xCaxThxPO4. ½ H2O rhabdophane was obtained and it appeared that there was a segregation between neodymium, calcium and thorium after a few days to several months depending on the thorium weight loadings and the precipitation time, thorium precipitating as TPHPH and neodymium as NdPO4  ½ H2O. The determination of the solubility constants showed very low values which means that these phases exhibit some interesting properties for the retention of radionuclides.
Pretreatment of Tc-Containing Waste and Its Effect on Tc-99 Leaching from Grouts
Authors: Aloy Albert , Kovarskaya Elena N , Harbour John R. , Langton Christine A. , Holtzscheiter E William
Published: October 2011

A salt solution (doped with Tc-99), that simulates the salt waste stream to be processed at the Saltstone Production Facility, was immobilized in grout waste forms with and without (1) ground granulated blast furnace slag and (2) pretreatment with iron salts. The degree of immobilization of Tc-99 was measured through monolithic and crushed grout leaching tests. Although Fe (+2) was shown to be effective in reducing Tc-99 to the +4 state, the strong reducing nature of the blast furnace slag present in the grout formulation dominated the reduction of Tc-99 in the cured grouts. An effective diffusion coefficient of 4.75 x 10-12 (Leach Index of 11.4) was measured using the ANSI/ANS-16.1 protocol. The leaching results show that, even in the presence of a concentrated salt solution, blast furnace slag can effectively reduce pertechnetate to the immobile +4 oxidation state. The measured diffusivity was introduced into a flow and transport model (PORFLOW) to calculate the release of Tc-99 from a Saltstone Vault as a function of hydraulic conductivity of the matrix.
Fluidized Bed Steam Reformed (FBSR) Mineral Waste Forms: Characterization and Durability Testing
Authors: Jantzen Carol , Lorier Troy H. , Pareizs John M. , Marra James C.
Published: October 2011

Fluidized Bed Steam Reforming (FBSR) is being considered as a potential technology for the immobilization of a wide variety of high sodium low activity wastes (LAW) such as those existing at the Hanford site, at the Idaho National Laboratory (INL), and the Savannah River Site (SRS). The addition of clay, charcoal, and a catalyst as co-reactants with the waste denitrates the aqueous wastes and forms a granular mineral waste form that can subsequently be made into a monolith for disposal if necessary. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage and ring structures and iron bearing spinel minerals. The mineralization occurs at moderate temperatures between 650-750°C in the presence of superheated steam. The cage and ring structured feldspathoid minerals atomically bond radionuclides like Tc-99 and Cs-137 and anions such as SO4, I, F, and Cl. The spinel minerals stabilize Resource Conservation and Recovery Act (RCRA) hazardous species such as Cr and Ni. Granular mineral waste forms were made from (1) a basic Hanford Envelope A low-activity waste (LAW) simulant and (2) an acidic INL simulant commonly referred to as sodium-bearing waste (SBW) in pilot scale facilities at the Science Applications International Corporation (SAIC) Science and Technology Applications Research (STAR) facility in Idaho Falls, ID. The FBSR waste forms were characterized and the durability tested via ASTM C1285 (Product Consistency Test), the Environmental Protection Agency (EPA) Toxic Characteristic Leaching Procedure (TCLP), and the Single Pass Flow Through (SPFT) test. The results of the SPFT testing and the activation energies for dissolution are discussed in this study.
Rare Earth Elements: A Tool for Understanding the Behaviour of Trivalent Actinides in the Geosphere
Authors: Buil Belen , Gómez Paloma , Garralón Antonio , Turrero M. Jesús
Published: October 2011

REE concentrations have been determined in groundwaters, granite and fracture fillings in a restored uranium mine.

The granitoids normalized REE patterns of groundwaters show HREE-enrichment and positive Eu anomalies. This suggests that the REE are fractionated during leaching from the source rocks by groundwaters. Preferential leaching of HREE would be consistent with the greater stability of their aqueous complexes compared to those of the LREE, together with the dissolution of certain fracture filling minerals, dissolution/alteration of phyllosilicates and colloidal transport.
Determination of Matrix Diffusion Properties of Granite
Authors: Holtta Pirkko , Siitari-Kauppi Marja , Huittinen Nina , Poteri Antti
Published: October 2011

Rock–core column experiments were introduced to estimate the diffusion and sorption properties of Kuru Grey granite used in block–scale experiments. The objective was to examine the processes causing retention in solute transport through rock fractures, especially matrix diffusion used to estimate the importance of retention processes during transport in different scales and flow conditions. Rock–core columns were constructed from cores drilled into the fracture and were placed inside tubes to form flow channels in the 0.5 mm gap between the cores and the tube walls. Tracer experiments were performed using uranine, HTO, 36Cl, 131I, 22Na and 85Sr at flow rates of 1–50 µlmin-1. Rock matrix was characterized using 14C–PMMA method, scanning electron microscopy (SEM), energy dispersive X–ray micro analysis (EDX) and the B.E.T. method.

Solute mass flux through a column was modelled by applying the assumption of a linear velocity profile and a molecular diffusion. Coupling of the advection and diffusion processes was based on the model of generalised Taylor dispersion in the linear velocity profile. Experiments could be modelled applying a consistent parameterization and transport processes. The results provide evidence that it is possible to investigate matrix diffusion at the laboratory scale. The effects of matrix diffusion were demonstrated on the slightly–sorbing tracer breakthrough curves. Based on scoping calculations matrix diffusion begins to be clearly observable for non–sorbing tracer when the flow rate is 0.1 μl×min-1. The experimental results presented here cannot be transferred directly to the spatial and temporal scales that prevail in an underground repository. However, the knowledge and understanding of transport and retention processes gained from this study is transferable to different scales from laboratory to in–situ conditions.
Surface Complexation of Neptunium(V) with Goethite
Authors: Jerden James L , Kropf A Jeremy
Published: October 2011

Batch adsorption experiments in which neptunium bearing solutions were reacted with goethite (alpha-FeOOH) have been performed to study uptake mechanisms in sodium chloride and calcium-bearing sodium silicate solutions. This paper presents results identifying and quantifying the mechanisms by which neptunium is adsorbed as a function of pH and reaction time (aging). Also presented are results from tests in which neptunium is reacted with goethite in the presence of other cations (uranyl and calcium) that may compete with neptunium for sorption sites. The desorption of neptunium from goethite has been studied by resuspending the neptunium-loaded goethite samples in solutions containing no neptunium. Selected reacted sorbent samples were analyzed by x-ray absorption spectroscopy (XAS) to determine the oxidation state and molecular speciation of the adsorbed neptunium. Results have been used to establish the pH adsorption edge of neptunium on goethite in sodium chloride and calcium-bearing sodium silicate solutions. The results indicate that neptunium uptake on goethite reaches 95% at a pH of approximately 7 and begins to decrease at pH values greater than 8.5. Distribution coefficients for neptunium sorption range from less than 1000 (moles/kg)sorbed / (moles/kg)solution at pH less than 5.0 to greater than 10,000 (moles/kg)sorbed / (moles/kg)solution at pH greater than 7.0. Distribution coefficients as high as 100,000 (moles/kg)sorbed / (moles/kg)solution were recorded for the tests done in calcite equilibrated sodium silicate solutions. XAS results show that neptunium complexes with the goethite surface mainly as Np(V) (although Np(IV) is prevalent in some of the longer-duration sorption tests). The neptunium adsorbed to goethite shows Np-O bond length of approximately 1.8 angstroms which is representative of the Np-O axial bond in the neptunyl(V) complex. This neptunyl(V) ion is coordinated to 5 or 6 equatorial oxygens with Np-O bond lengths of 2.45 angstroms. The absence of a clearly recognizable Np-Fe interaction for the sodium chloride sorption tests suggests that neptunium in these solutions adsorbs as an outer-sphere complex. XAS results from the calcium-bearing sodium silicate sorption tests show evidence for a neptunyl(V) inner-sphere surface complex with a Np-Fe interaction at 3.5 angstroms. Desorption tests indicate that samples in which neptunium is bound as inner-sphere complexes show significant sorption hysteresis relative to samples in which neptunium is bound largely as outer-sphere complexes.
Perrhenate and Pertechnetate Behavior on Iron and Sulfur-Bearing Compounds
Authors: Anderson B. Elizabeth , Becker U. , Helean K. B. , Ewing R. C.
Published: October 2011

Investigations on the behavior of the radioactive element technetium frequently use a stable isotope of rhenium as an analogue. This is justified by citing the elements' similar radii, major oxidation states of +7 and +4, and eH-pH diagrams. However, recent studies (e.g.,[1] have shown this analogy to be imperfect. Therefore, one goal of our study is to compare the behavior of these elements with emphasis on the adsorption of perrhenate and pertechnetate (the major forms of Re and Tc in natural waters) on mineral surfaces.

Quantum mechanical calculations were performed on the adsorption of these two anions on relaxed clusters of the well-characterized sulfide galena (PbS) and some other Fe and S-bearing materials. With these calculations, we gain insight into differences between the anions' adsorption behavior, including geometry, adsorption energies, and electronic structure. Differences between interactions on terraces and step edges, the effects of co-adsorbates such as Na+ and Cl-, and chloride complexation are also explored. The influence of water was calculated using homogeneous dielectric fluids.

As a complement to the calculations, batch sorption tests are in progress involving ReO4-/TcO4- solution in contact with Fe metal, 10% Fe-doped hydroxyapatite, goethite, hematite, magnetite, pyrite, galena, and sphalerite.
Coupling Hydrological and Geochemical Simulations to Assess Spatial Heterogeneity and Chemical Evolution of Groundwaters at Two Candidate Repository Sites in Sweden
Authors: Puigdomenech Ignasi , Gimeno María José , Gómez Javier B. , Puigdomenech Ignasi
Published: October 2011

The chemical composition of groundwater surrounding a high level radioactive waste re-pository is of importance to many factors that affect repository performance. The geochemical characteristics of Swedish groundwater systems are governed by successive mixing events be-tween several end-member waters during their paleogeographical evolution. An approach is pro-posed here to investigate the spatial and temporal evolution of groundwater geochemical condi-tions by coupling hydrogeological and geochemical models in a sequential way.

The procedure combines hydrogeological results by others of a discrete fracture net-work using CONNECTFLOW with a mixing and reaction-path simulation using PHREEQC. The hydrological results contain mixing proportions of four reference waters (a deep brine, gla-cial meltwater, marine water, and meteoric infiltration) at each time step and at every node of the 3D model domain. In this work mixing fractions are fed into PHREEQC using software devel-oped to build formatted input files and to extract the information from output files for subsequent plotting and analysis. The geochemical calculations included both chemical mixing and equilib-rium reactions with selected minerals: calcite, chalcedony and an Fe(III) oxyhydroxide.

Some results for the Forsmark site, about 170 km north of Stockholm, Sweden, are graphi-cally presented. Cross sections, where each node is color-coded with respect to an important variable (pH, Eh or concentrations of main elements), are used to visualize the future evolution of the site. Sensitivity analyses were made to evaluate the effects of the different reactions and/or assumptions. The proposed methodology has proved useful for evaluating the future geochemical evolution of the repository sites and to increase the confidence in the site descriptions.
Water, Vapor, and Salt Dynamics in a Hot Repository
Authors: Bahrami Davood , Danko George , Walton John
Published: October 2011

The purpose of this paper is to report the results of a new model study critically examining the high temperature nuclear waste disposal concept at Yucca Mountain using MULTIFLUX, an integrated in-drift- and mountain-scale thermal-hydrologic model. In addition to new results the paper summarizes results of a previous study. The results show that a large amount of vapor flow into the drift is expected during the period of above-boiling temperatures in the emplacement drift. This phenomenon makes the emplacement drift a water/moisture attractor for thousands of years during the above-boiling temperature operation.

The evaporation of the percolation water into the drift gives rise to salt accumulation in the rock wall, especially in the crown of the drift for about 1500 years in the example. The deposited salts over the drift footprint, almost entirely present in the fractures, may enter the drift either by rock fall or by water drippage. During the high temperature operation mode the barometric pressure variation creates fluctuating relative humidity in the emplacement drift with a time period of approximately 10 days. Potentially wet and dry conditions and condensation on the surfaces over salt-laden drift wall sections are unfavorable to the storage environment. Corrosive salt accumulation during the above-boiling temperature operation must be sufficiently addressed to fully understand the waste package environment during the thermal period. Until the questions are resolved, a below-boiling repository design is favored where the Alloy-22 will be less susceptible to localized corrosion.
Specialized Disposal Sites for Different Reprocessing Plant Wastes
Authors: Forsberg Charles W. , Driscoll Michael J.
Published: October 2011

Once-through fuel cycles directly dispose of one primary waste form: spent nuclear fuel (SNF). In contrast, the reprocessed SNF yields multiple waste streams with different chemical, physical, and radionuclide characteristics. These different characteristics of each waste stream imply that there are potential cost and performance benefits to developing different disposal sites that best match the disposal requirements of each waste stream. Disposal sites as defined herein may be located in different geologies or in a single repository containing multiple sections, each with different design characteristics. The paper describes the results of a series of studies on disposal options for specific wastes and the potential for a waste management system that better couples various reprocessing plant wastes with disposal facilities.
Políticas para o ensino médio no Brasil: perspectivas para a universalização
Authors: Melo Savana Diniz Gomes , Duarte Adriana
Published: October 2011

Este artigo busca analisar as inflexões ocorridas nas políticas para o ensino médio no Brasil, a partir de 2007, problematizando o contexto em que foram produzidas e as contradições presentes nesse processo. Procura identificar as mudanças empreendidas, os discursos que lhes deram sustentação e as medidas e programas governamentais decorrentes. Retrata e analisa essas mudanças e suas implicações no âmbito dos estados, enfocando o caso de Minas Gerais. Com base nos argumentos reunidos, aponta algumas considerações e tendências observadas no rumo traçado pelas políticas atuais, no que tange às finalidades e à universalização dessa etapa da educação básica no país.
Navegação na artroplastia total do joelho: existe vantagem?
Authors: Matos Luiz Felipe Carvalho , Alves André Lopes Quintas , Sobreiro Alberto Lima , Giordano Marcos Noberto , Albuquerque Rodrigo Satamini Pires de , Carvalho Antônio Carlos Pires
Published: October 2011

OBJETIVO: Avaliar se a cirurgia auxiliada por navegação oferece vantagens sobre a técnica convencional, foi desenvolvido um estudo randômico, prospectivo e comparativo analisando o posicionamento do implante, alinhamento do membro, tempo de cirurgia, perda sanguínea e reabilitação funcional. MÉTODOS: Foram estudados 39 pacientes submetidos a 42 Artroplastias Totais de Joelho. No grupo 1 (n=21) a cirurgia foi navegada e no grupo 2 (n=21) convencional. Os pacientes foram avaliados com radiografia panorâmica de membros inferiores, tomografia computadorizada e pelo Knee Society Score (KSS) no pré-operatório e com três meses de pós-operatório. O tempo de cirurgia e a perda sanguínea pós-operatória também foram avaliados. RESULTADOS: O tempo de cirurgia foi maior no grupo 1. Não houve diferença significativa quanto à perda sanguínea e ao KSS. Houve maior proximidade dos três graus de rotação externa e dos cinco graus de inclinação coronal nos pacientes do grupo 2. O eixo mecânico aproximou-se mais de zero grau no grupo 1. CONCLUSÕES: A navegação promove um posicionamento individualizado dos componentes da prótese oferecendo vantagens no realinhamento do membro. O tempo cirúrgico tende a ser maior na técnica navegada, porém, não foi estatisticamente significante. Não há diferenças na perda sanguínea e na melhora do KSS. Nivel de Evidência I, estudo terapeutico.
Desempenho muscular, dor, rigidez e funcionalidade de idosas com osteoartrite de joelho
Authors: Santos Mary Luci Avelar Di Sabatino , Gomes Wellington Fabiano , Queiroz Bárbara Zille de , Rosa Nayza Maciel de Brito , Pereira Daniele Sirineu , Dias João Marcos Domingues , Pereira Leani Souza Máximo
Published: October 2011

OBJETIVO: Verificar a correlação do desempenho dos músculos do joelho e os domínios dor, rigidez e funcionalidade do Questionário Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) de idosas com osteoartrite de joelho (OA). MÉTODOS: Estudo transversal observacional com uma amostra de 80 idosas (71,2 ± 5,3 anos) com diagnóstico clínico de OA de joelho. Força, resistência e equilíbrio musculares foram avaliados por meio do dinamômetro isocinético Biodex System 3 Pro, nas velocidades angulares de 60º/s e 180º/s; a funcionalidade, presença de dor e rigidez foram avaliadas pelo questionário WOMAC. A correlação entre as variáveis foi analisada pelo teste de Spearman. RESULTADOS: Houve correlação inversa significativa da força e resistência musculares do quadríceps (QUA) e isquiossurais (IQS) nas velocidades de 60º/s e 180°/s, respectivamente, e da relação de equilíbrio muscular IQS/QUA a 180°/s com todos os domínios do WOMAC (p<0.05). CONCLUSÕES: A redução da força e da resistência e a presença de desequilíbrio dos músculos do joelho correlacionaram-se inversamente com todos os domínios do WOMAC, apontando para a necessidade de intervenções que envolvam um trabalho de fortalecimento, resistência e equilíbrio muscular de extensores e flexores de joelho, visando a redução do impacto da OA na dor, rigidez e funcionalidade do idoso. Nivel de Evidência I, Estudos diagnósticos, Investigação de um exame para diagnóstico.
Fluxograma diferencial entre a artrite séptica e sinovite transitória do quadril em crianças
Authors: Rosa João Roberto Polydoro , Kojima Claudio Marcos , Fernandes Laura Filippini Lorimier , Hehn Bruno Jacopucci , Santili Cláudio
Published: October 2011

O diagnóstico diferencial entre a artrite séptica e a sinovite transitória do quadril não é fácil de ser realizado, pois não há um exame que seja simples, nem satisfatoriamente sensível e específico para diferenciá-las. Sendo assim, é muitas vezes utilizada uma propedêutica armada de exames que demanda maior custo e requer melhor infra-estrutura da instituição de saúde. Perante isso, torna-se evidente a necessidade de uma análise multifatorial dos dados clínicos e laboratoriais envolvidos para a proposição de um fluxograma em que se possa racionalizar exames visando a correta abordagem e evitar a indicação de procedimentos, muitas vezes, desnecessários como a ressonância magnética ou mais invasivos como a artrocentese e a própria drenagem cirúrgica. Realizamos uma ampla revisão da literatura nas bases de dados do Pubmed e Cochrane até maio de 2009 em que foi analisada a importância do exame clínico, dos testes laboratoriais e de imagem para a diferenciação entre as duas afecções. Mediante o cruzamento dos dados foi elaborado um fluxograma para o diagnóstico e conduta na criança e no adolescente, com idade de seis meses a dezoito anos, com sintoma de dor no quadril, na suspeita de quadro inflamatório. Nivel de Evidência III, estudos diagnósticos, investigação de um exame para diagnóstico.
Impacto do posicionamento da placa na osteotomia em cunha de fechamento lateral em cúbito varo
Authors: Yu Min , Wang Wan-Chun , Ni Jiang-Dong , Li Yu-Jia
Published: October 2011

OBJETIVO: O cúbito varo é uma doença muito comum em crianças e adultos, ocasionada por fratura supracondilar. Existem vários procedimentos cirúrgicos e fixações internas para correção do cúbito varo, com diferentes desfechos, embora a fixação interna com placa e parafusos seja o mais comum. Contudo, o impacto do posicionamento da placa sobre a cirurgia raramente foi estudado até agora. MÉTODO: Em nosso estudo, 12 pacientes com cúbito varo foram divididos em dois grupos, operados pelo método de osteotomias em cunha com fechamento lateral e fixações internas com placa e parafusos. Em um grupo, as placas foram colocadas no lado póstero-lateral; no outro, as placas foram colocadas no lado lateral do úmero. RESULTADO: O período de acompanhamento foi 4,5 meses (faixa de 2 a 7 meses). Houve cinco resultados excelentes (83,3%) e um bom (16,7%) em cada grupo. Em todos os casos, a aparência é muito semelhante ao lado oposto; não há diferenças de amplitude de movimento (AM) no cotovelo depois da cirurgia. Um paciente no grupo B teve paralisia nervosa transitória; não houve infecções nem osteomielite. CONCLUSÃO: A posição da placa de fixação interna não tem impacto sobre a osteotomia em cunha de fechamento lateral. Nivel de Evidência II, Prospectivo Comparativo.
Irrigação, matéria orgânica e cobertura morta na produção de mudas de cumaru (Amburana cearensis)
Authors: Pimentel João V. F. , Guerra Hugo O. C.
Published: October 2011

Conduziu-se um experimento em um viveiro visando estudar os efeitos da irrigação, da adubação orgânica e da cobertura morta no solo, sobre o crescimento das mudas de cumaru (Amburana cearensis), planta nativa de múltiplas utilidades. Cinco quantidades de água foram aplicadas no solo, determinadas em função da evapotranspiração (0,25; 0,50; 0,75; 1,00; 1,25 ET); três níveis de esterco de boi no solo, como fração do volume total do solo (0,25; 0,50; 0,75) e presença e ausência de cobertura morta. O delineamento experimental foi em blocos casualizados, com quatro repetições. Aos 147 dias após a semeadura, observou-se que, com exceção da altura das plantas, afetada pela cobertura do solo, nenhuma das variáveis estudadas foi afetada significativamente pelos tratamentos utilizados. O cumaru parece adaptar-se às condições adversas de água e matéria orgânica no solo. A presença de cobertura morta no solo além de aumentar a altura das mudas significou uma economia de 41% da água de irrigação utilizada.
Metodologia para determinação das necessidades nutricionais de melão e melancia
Authors: Paula José A. de A. , Medeiros José F. de , Miranda Neyton de O. , Oliveira Francisco de A. de , Lima Carlos J. G. de S.
Published: October 2011

Realizou-se este trabalho visando definir a necessidade nutricional de nitrogênio, fósforo e potássio de melão e melancia, em função da produtividade esperada, a partir de dados médios citados na literatura, e validá-los com dados obtidos em experimentos com melão e melancia, realizados no Agropolo Assu/Mossoró. O experimento com melão seguiu o delineamento em blocos ao acaso, com três repetições, no esquema fatorial 3 x 3 + 3, que constou da combinação de três doses de N (N1 = 42, N2 = 84 e N3 = 126 kg ha-1) e de K (K1 = 106, K2 = 212 e K3 = 322 kg ha-1), mais três tratamentos adicionais (N0K0, N0K2 e N2K0), sendo que N0 e K0 não receberam N nem K. O experimento com melancia seguiu o mesmo delineamento experimental, modificando as doses de N (N1 = 45, N2 = 91 e N3 = 136 kg ha-1) e de K (K1 = 78, K2 = 156 e K3 = 234 kg ha-1), havendo dois tratamentos adicionais (N0K2 e N2K0). O modelo que melhor se ajustou, tanto para a melancia como para o melão, seguiu a relação produtividade (kg planta-1) x nutrientes exportados (g planta-1). Os índices de concordância observados entre os valores estimados pelo modelo de absorção total de N e K e valores obtidos experimentalmente, são considerados aceitáveis, tanto para melancia como para melão.
Uso de bentonita na remediação de solos contaminados com zinco: efeito na produção de feijão
Authors: Tito Gilvanise A. , Chaves Lucia H. G. , Guerra Hugo O. C. , Soares Frederico A. L.
Published: October 2011

Diversos procedimentos têm sido propostos para reduzir a concentração de metais pesados nos solos, e, conseqüentemente, seus efeitos poluidores. Dentre eles destacam-se a aplicação de materiais, como a bentonita, capazes de adsorver estes elementos, tornando-os menos disponíveis para as plantas. Objetivou-se com este trabalho avaliar a capacidade da bentonita na remediação de solos contaminados com zinco. Conduziu-se experimento em condições de casa de vegetação com delineamento inteiramente casualizado com três repetições e uma planta por parcela, utilizando-se como planta indicadora o feijão caupi (Vigna unguiculata L.). Os tratamentos consistiram de uma combinação fatorial 3 x 3, sendo o primeiro fator composto por três doses de Zn (50, 250 e 450 mg kg-1) e o segundo fator por três doses de bentonita (0, 30 e 60 t ha-1). Para o estudo, utilizou-se vasos com capacidade de18 kg, preenchidos com 15 kg de solo em mistura com as respectivas doses de bentonita e com o zinco. Os tratamentos permaneceram incubados por um período de 10 dias, e em seguida foi realizada a semeadura da planta indicadora. Aos 65 dias após a semeadura colheram-se folhas, caules, raízes, sementes e casca, que, depois de secos em estufa de circulação de ar (65°C), foram pesados, moídos e analisados quanto aos teores de zinco. Os resultados evidenciaram que a bentonita parece ser um excelente material inorgânico para remediar solos contaminados com zinco. A incorporação de bentonita ao solo aumenta a adsorção do zinco diminuindo a disponibilidade deste elemento para a planta tendendo, consequentemente, aumentar a produção de massa seca.
Modelagem da variação horária da temperatura do ar em Petrolina, PE, e Botucatu, SP
Authors: Ramos Clóvis M. C. , Silva Alessandra F. da , Sartori Anderson A. da C. , Zimback Célia R. L. , Bassoi Luís H.
Published: October 2011

A temperatura do ar é um elemento climático de interesse para diversos estudos relacionados à produção agrícola. A partir de dados de temperatura do ar de Botucatu, SP, e Petrolina, PE (diferentes classificações climáticas), medidos entre janeiro de 2004 e dezembro de 2005, foram selecionados dados pontuais com intervalos de seis horas entre cada observação para cada dia. Desta forma, foram analisados três conjuntos de dados, variando a hora do primeiro registro, utilizando a técnica de geoestatística com o intuito de verificar e quantificar o grau de dependência temporal entre as observações. Comprovada a dependência temporal, o método da krigagem ordinária foi utilizado a fim de modelar a variação da temperatura do ar com o intervalo de uma hora. A análise geoestatística demonstrou a dependência temporal com ajuste ao modelo esférico, em ambas as localidades, (alcance de 11,6 h para Botucatu e 12,7 h para Petrolina). Para ambas as localidades o horário de medida da temperatura do ar, foi fator importante na exatidão de estiamtiva da variação da temperatura. Os registros às 2, 8, 14 e 20 h e às 4, 10, 16 e 22 h, geraram modelos com melhor desempenho, os modelos baseados nos registros às 9, 15 e 21 h, mostraram desempenho inferior.
Fatores-chave de sucesso para sistemas de indicadores de desempenho para benchmarking colaborativo entre empresas construtoras
Authors: Costa Dayana Bastos , Formoso Carlos Torres
Published: October 2011

Nos últimos anos, diversas iniciativas têm sido realizadas para o desenvolvimento de clubes de benchmarking e sistemas de indicadores de desempenho para benchmarking, em diferentes países. Estes clubes consistem em grupos colaborativos, nos quais diferentes empresas podem adquirir e compartilhar conhecimentos. Entretanto, ainda são escassos os estudos que discutem sob quais condições estes processos colaborativos mostram-se eficazes e os reais benefícios alcançados pelas empresas. O presente artigo tem como objetivo principal identificar os fatores-chave de sucesso para a construção de sistemas de indicadores para benchmarking por meio de processo colaborativo entre empresas construtoras. Este artigo apresenta ainda a definição de um conjunto de indicadores para benchmarking, uma estrutura para avaliação do grau de maturidade dos sistemas de indicadores das empresas construtoras participantes, assim como a identificação das melhorias implementadas nos sistemas de indicadores pelas empresas. No presente trabalho, foi utilizada a estratégia da pesquisa-ação, tendo sido realizado um estudo com um grupo de vinte empresas de construção, as quais formaram um clube de benchmarking.
Use of sodium chloride and zeolite during shipment of Ancistrus triradiatus under high temperature
Authors: Ramírez-Duarte Wilson F. , Pineda-Quiroga Carolina , Martínez Nhora , Eslava-Mocha Pedro R.
Published: October 2011

The use of sodium chloride (0.5 g/L and 1 g/L) and zeolite (22.7 g/L) during shipment (48 h) of Ancistrus triradiatus at high temperatures (between 24.5 and 34ºC) were evaluated. Several water quality parameters (dissolved oxygen, pH, conductivity, and total ammonia) were measured before and after shipment. Glycemia was measured before shipment and at 24 and 48 h after shipment. After shipment, a resistance test was carried out in a high concentration of sodium chloride, and mortality was recorded after shipment, and 7 days post-shipment. While the two evaluated substances increased survival of A. triradiatus challenged by high temperatures during shipment, the best result was obtained with 1 g/L of sodium chloride.
Mixed-species schooling behavior and protective mimicry involving coral reef fish from the genus Haemulon (Haemulidae)
Authors: Pereira Pedro Henrique Cipresso , Feitosa João Lucas Leão , Ferreira Beatrice Padovani
Published: October 2011

The present study analyzed heterotypic schooling behavior and protective mimicry relationships involving species of the genus Haemulon and other coral reef fishes on coastal reefs at Tamandaré, Pernambuco State, Northeastern Brazil. The work was performed during 35 hours of direct observation using the "focal animal" method. The observed events involved 14 species of reef fish in eight different families. The phenomenon of mixed schooling appeared to be related to the large number of individuals of the genus Haemulon present in reef environments and to the tendency of individuals with limited populations to try to aggregate in schools (e.g. genus Scarus).
Perspectives on supercapacitors, pseudocapacitors and batteries
Authors: Bakker Martin G. , Frazier Rachel M. , Burkett Susan , Bara Jason E. , Chopra Nitin , Spear Scott , Pan Shanlin , Xu Cailing
Published: October 2011

With the anticipated increase in renewable wind and solar energy, efficient storage of electrical energy for balancing energy generation and demand on various time scales is becoming increasingly important. This review summarises the fundamentals of electrical energy storage in capacitors and batteries, discusses the similarities and differences of the two classes of devices and addresses the potential impact of the current research. A number of new materials and device structures that are anticipated to play roles in new devices are reviewed in greater detail. Topics covered are carbon nanotubes (CNTs), graphene, nanostructured transition metal oxides, silicon-based devices, ionic liquids (ILs), ion-conductive polymers and asymmetric supercapacitors.
Paraffin Wax Deposition: Mitigation & Removal Techniques
Authors: Al-Yaari Mohammed
Published: October 2011

Flow assurance is critical and difficult for deepwater pipeline since the seawater temperature, surrounding pipeline, is usually much colder than the surface air temperature. In the deepwater, the fluid heat can be quickly lost to the water if there is no thermal insulation layer surrounding the pipe wall. When the inner wall temperature falls below the crude oil cloud point temperature, wax deposition occurs. Such problem starts when paraffin components in crude oil precipitate and deposit on the cold pipeline wall. Whereas wax precipitation during oil flow results in wax deposition and flow restriction, wax precipitation during a production shutdown results in problems when attempting to restart the flow.

In this review, wax deposition problem in flow and during the shut-in conditions are discussed. Also, proposed wax deposition physics and mechanisms are outlined. Furthermore, different wax deposition mitigation techniques are explained. These techniques include: Cold Flow, Chemical Additives and Different Pipes and Coatings Techniques. In addition, different wax deposition removal techniques are reviewed. These techniques include: Fused Chemical Reaction, Mechanical Techniques, Heat Application, Chemical Additives, Magnetic Fluid Conditioning (MFC) technology and Use of Microbial Products.
Artificial Intelligence Application in Reservoir Characterization and Modeling: Whitening the Black Box
Authors: Anifowose Fatai Adesina
Published: October 2011

There are two schools of thought on the application of Artificial Intelligence (AI) techniques in reservoir characterization and modeling. The first school considers AI as a step forward in the future of reservoir characterization and modeling in line with the increased advancement in technology. The other school argues that AI techniques are "black boxes" with vague architectures, whose concepts do not follow fundamental petroleum engineering principles.

This paper presents AI as a "white box", highlighting its basic concepts, revealing the architectural composition of some of its techniques, and showcasing examples of its successful applications in various reservoir characterization and modeling tasks. AI techniques are used in the prediction of oil and gas reservoir properties such as porosity, permeability, water saturation, well-bore stability and identification of lithofacies. The recent developments in the hybridization and "ensemblage" of some AI techniques are also discussed.

The outcome of this paper will provide a better understanding of the basic concepts of AI and offer a strong background for further study of AI techniques. Overall, it will provide an appraisal of the successful applications of AI in petroleum engineering and increase the necessary synergy required for a multi-disciplinary collaboration among petroleum engineers, computer scientists and mathematicians; and to ensure the delivery of the future AI-driven/AI-assisted reservoir models for better exploration, production and management of petroleum resources.