bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiolysis and Ageing of C2-BTP in Cinnamaldehyde/Hexanol Mixtures
Authors: Fermvik Anna , Ekberg Christian , Retegan Teodora , Skarnemark Gunnar
Published: October 2011

The separation of actinides from lanthanides is an important step in the alternative methods for nuclear waste treatment currently under development. Polycyclic molecules containing nitrogen are synthesised and used for solvent extraction. A potential problem in the separation process is the degradation of the molecule due to irradiation or ageing. An addition of nitrobenzene has proved to have an inhibitory effect on degradation when added to a system containing C2-BTP in hexanol before irradiation. In this study, 2,6 di(5,6 diethyl 1,2,4 triazin 3 yl)pyridine (C2-BTP) was dissolved in different mixtures of cinnamaldehyde and hexanol and the effects on extraction after ageing and irradiation were investigated. Similar to nitrobenzene, cinnamaldehyde contains an aromatic ring which generally has a relatively high resistance towards radiolysis. Both C2-BTP in cinnamaldehyde and C2-BTP in hexanol seem to degrade with time. The system with C2-BTP in pure hexanol is relatively stable up to 17 days but then starts slowly to degrade. The solution with pure cinnamaldehyde as diluent started to degrade after only ∼20 hours. The opposite is true for degradation caused by radiolysis; hexanol systems are more sensitive to radiolysis than cinnamaldehyde systems. Most of the radiolytic degradation took place during the first days of irradiation, up to a dose of 4 kGy.
Application of a Comprehensive Sensitivity Analysis Method on the Safety Assessment of TRU Waste Disposal in JAPAN
Authors: Ohi Takao , Takase Hiroyasu , Inagaki Manabu , Oyamada Kiyoshi , Sone Tomoyuki , Mihara Morihiro , Ebashi Takeshi , Nakajima Kunihiko
Published: October 2011

A comprehensive sensitivity analysis method has been developed with the aim of providing quantitative information in an efficient manner. This methodology is composed of the following two components: (1) a statistical method with random sampling of independent parameters, which identifies important parameters and extracts threshold values of parameters and/or combinations yielding a 'successful condition' where maximum dose does not exceed a target value, (2) A nuclide migration model that as far as possible incorporates a comprehensive set of phenomena occurring within the repository. This approach was applied as part of a safety assessment of the geological disposal of TRU waste in Japan (TRU-2). It was shown that the concept of TRU waste disposal is robust from the point of view of safety.
Development of Ceramic Waste Forms for High-Level Nuclear Waste over the Last 30 years
Authors: Vance Eric
Published: October 2011

Many types of ceramics have been put forward for immobilisation of high-level waste (HLW) from reprocessing of nuclear power plant fuel or weapons production. After describing some historical aspects of waste form research, the essential features of the chemical design and processing of these different ceramic types will be discussed briefly. Given acceptable laboratory and long-term predicted performance based on appropriately rigorous chemical design, the important processing parameters are mostly waste loading, waste throughput, footprint, offgas control/minimisation, and the need for secondary waste treatment. It is concluded that the “problem of high-level nuclear waste” is largely solved from a technical point of view, within the current regulatory framework, and that the main remaining question is which technical disposition method is optimum for a given waste.
Hydrothermal Methods as a New Way of Actinide Phosphate Preparation
Authors: Clavier Nicolas , Dacheux Nicolas , Wallez Gilles , Quarton Michel
Published: October 2011

Precipitation processes driven in hydrothermal conditions were applied to the preparation of phosphate-based ceramics. Three systems composed by a crystallized precursor linked with a high temperature compound were particularly examined: M(OH)PO4 / M2O(PO4)2 (M = Th, U), MPO40.5 H2O / MPO4 (M = La - Dy) and Th2-x/2Anx/2(PO4)2(HPO4) H2O / β-Th4-xAnx(PO4)4P2O7 (M = U, Np, Pu). A significant improvement of several physico-chemical properties of the powders, especially in the sintering capability and the homogeneity of the final solids was evidenced when starting from the precursors. Furthermore, these phases were also found to control the solubility of lanthanides and actinides during leaching experiments when reaching the saturation conditions in the solution.
Rare Earth-Bearing Murataite Ceramics
Authors: Stefanovsky Sergey , Yudintsev Sergey , Nikonov Boris , Stefanovsky Olga
Published: October 2011

Phase composition of the murataite-based ceramics containing 10 wt.% lanthanum, cerium, neodymium, europium, gadolinium, yttrium, zirconium oxides was studied. The ceramics were prepared by melting of oxide mixtures in glass-carbon ampoules in air at ∼1500° C. They are composed of predominant murataite-type phases and minor extra phases: rutile, crichtonite, perovskite, ilmenite/pyrophanite, and zirconolite (in the Zr-bearing sample only). Three murataite-related phases with five- (5C), eight- (8C), and three-fold (3C) elementary fluorite unit cell are normally present in all the ceramics. These phases form core, intermediate zone, and rim of the murataite grains, respectively. They are predominant host phases for the rare earth elements whose concentrations are reduced in a row: M-5C>M-8C>M-3C. Appreciate fraction of La and Ce may enter the perovskite phase.
Synroc-D Type Ceramics Produced by Hot Isostatic Pressing and Cold Crucible Melting for Immobilisation of (Al, U) Rich Nuclear Waste
Authors: Vance Eric R. , La Robina Michael , Li Huijun , Davis Joel
Published: October 2011

A synroc-D ceramic consisting mostly of spinel, hollandite, pyrochlore-structured CaUTi2O7, UO2, and Ti-rich regions shows promise for immobilisation of a HLW containing mainly Al and U, together with fission products. Ceramics with virtually zero porosities and waste loadings of 50-60 wt% on an oxide basis were prepared by cold crucible melting (CCM) at ∼1500°C, and also by subsolidus hot isostatic pressing (HIP) at 1100°C to prevent volatile losses. PCT leaching test values for Cs were < 13 g/L, with all other normalised elemental extractions being well below 1 g/L.
Experimental Study and Monte Carlo Modeling of Calcium Borosilicate Glasses Leaching
Authors: Arab Mehdi , Cailleteau Celine , Angeli Frederic , Devreux Francois
Published: October 2011

During aqueous alteration of glass an alteration layer appears on the glass surface. The properties of this alteration layer are of great importance for understanding and predicting the long-term behavior of high-level radioactive waste glasses. Numerical modeling can be very useful for understanding the impact of the glass composition on its aqueous reactivity and long-term properties but it is quite difficult to model these complex glasses. In order to identify the effect of the calcium content on glass alteration, seven oxide glass compositions (57SiO2 17B2O3 (22−x)Na2O xCaO 4ZrO2; 0 < x < 11) were investigated and a Monte Carlo model was developed to describe their leaching behavior. The specimens were altered at constant temperature (T = 90°C) at a glass-surface-area-to-solution-volume (SA/V) ratio of 15 cm 1 in a buffered solution (pH 9.2). Under these conditions all the variations observed in the leaching behavior are attributable to composition effects. Increasing the calcium content in the glass appears to be responsible for a sharp drop in the final leached boron fraction. In parallel with this experimental work, a Monte Carlo model was used to investigate the effect of calcium content on the leaching behavior. The glass structure was built with a random distribution of silicon and boron on the lattice points of a diamond lattice with sodium atoms located in interstitial position. The model was upgraded to take into account the effect of zirconium and calcium. Zirconium atoms are placed in interstitial position (with cations acting as charge compensators) and interact with six lattice atoms (Si or B) by decreasing their dissolution probability. Acting like sodium but with less effect, calcium atoms increase the dissolution probability of atoms placed in their neighborhood. Monte Carlo simulations performed with this model are in good agreement with the experimental results. The dependence of the dissolution rate on the calcium content can be described by a quadratic function: fitting the simulated points gives a minimum alteration rate at about 7.4 mol% calcium. This value is consistent with the figure of 8.0 mol% obtained from the experimental work. The model was also used to investigate the role of calcium in the glass structure and it pointed out that calcium act preferentially as a network modifier rather than a charge compensator in this kind of glasses.
The Influence of Preoxidation on the Corrosion of Copper Nuclear Waste Canisters in Aqueous Anoxic Sulphide Solutions
Authors: Smith Jared M. , Qin Z. , Wren J. C. , Shoesmith D. W.
Published: October 2011

Scandinavian/Canadian high-level nuclear waste repository conditions are expected to evolve from initially warm and oxic to eventually cool and anoxic. During the warm oxic period, corrosion products will accumulate on the container surface. These deposits could impede the reaction of Cu with aqueous sulphide, the only reaction that could lead to the significant accumulation of additional corrosion damage under the long-term anoxic conditions. The kinetics of reaction of Cu with aqueous sulphide solutions have been studied using electrochemical and surface analytical techniques. Corrosion potential measurements were used to follow the evolution of the surface as oxides/hydroxides were converted to sulphides in the sulphide concentration range 10-5 to 10-3 mol/L. Changes in composition were followed by in-situ Raman spectroscopy. Of critical importance is whether or not a period of preoxidation of a Cu container surface can prevent subsequent reaction of the surface with remotely produced sulphide
Geopolymers as Candidates for the Immobilisation of Low- and Intermediate-Level Waste
Authors: Vance Eric , Vance Eric , Kiyama Satoshi , Aly Zaynab , Yee Patrick
Published: October 2011

Geopolymers should be serious waste form candidates for intermediate level waste (ILW), insofar as they are more durable than Portland cement and can pass the PCT-B test for high-level waste. Thus an alkaline ILW could be considered to be satisfactorily immobilised in a geopolymer formulation. However a simulated Hanford tank waste was found to fail the PCT-B criterion even for a waste loading as low as 5 wt%, very probably due to the formation of a soluble sodium phosphate compound(s). This suggests that it could be worth developing a “mixed” GP waste form in which the amorphous material can immobilise cations and a zeolitic component to immobilise anions. The PCT -B test is demonstrably subject to significant saturation effects, especially for relatively soluble waste forms.
Frequency Characteristics of Acoustic Emission Signals from Cementitious Wasteforms with Encapsulated Al
Authors: Spasova Lyubka , Ojovan Michael I.
Published: October 2011

Acoustic emission (AE) signals were continuously recorded and their intrinsic frequency characteristics examined in order to evaluate the mechanical performance of cementitious wasteform with encapsulated Al waste. The primary frequency in the power spectrum and its range of intensity for the detected acoustic waves were potentially related with appearance of different micromechanical events caused by Al corrosion within the encapsulating cement system. In addition the process of cement matrix hardening has been shown as a source of AE signals characterised with essentially higher primary frequency (above 2 MHz) compared with those due to Al corrosion development (below 40 kHz) and cement cracking (above 100 kHz).
Phase Relations and Elemental Distribution Among Co-Existing Phases in the Ceramics of the Pseudobinary System CaZrTi2O7-LnAlO3 (Ln= Nd, Sm)
Authors: Stefanovsky Sergey , Stefanovsky Sergey , Ochkin Alexander
Published: October 2011

In the ceramics in series (1-õ) CaZrTi2O7 – x NdAlO3 and (1-õ) CaZrTi2O7 – x SmAlO3 (õ = 0.25, 0.5 and 0.75) produced by cold pressing and sintering at 1400, 1450 and 1500 0Ñ zirconolite was found to be a major phase, perovskite was an extra phase and traces of residual baddeleyite occurred. At x = 0.75 the perovskite was major phase and zirconolite and cubic oxide of fianite or tazheranite type were extra phases. Major Nd and Sm host phase at x = 0.25 was found to be zirconolite (about 65% of total Nd2O3 and 74% of total Sm2O3). With the x value increasing perovskite becomes major host phase for Nd and Sm accumulating of up to about 92% of total Nd and about 72% of total Sm. As follows from SEM/EDS data Nd and Sm contents in the zirconolite may reach ∼1 formula unit (fu).
Partitioning and Leaching Behavior of Actinides and Rare Earth Elements in a Zirconolite-bearing Hydrothermal Vein System
Authors: Payne Timothy E , Giere Reto , Hart Kaye P , Lumpkin Gregory R , McGlinn Peter J
Published: October 2011

Chemical extraction techniques and scanning electron microscopy were used to study the distribution and behavior of actinides and rare earth elements (REE) in hydrothermal veins at Adamello, (Italy). The six samples discussed in this paper were from the phlogopite zone, which is one of the major vein zones. The samples were similar in their bulk chemical composition, mineralogy, and leaching behavior of major elements (determined by extraction with 9M HCl). However, there were major differences in the extractability of REE and actinides. The most significant influence on the leaching characteristics appears to be the amounts of U, Th and REE incorporated in resistant host phases. Uranium and Th are very highly enriched in zirconolite grains. Actinides were more readily leached from samples with a higher content of U and Th, relative to the amount of zirconolite. The results show that REE and actinides present in chemically resistant minerals can be retained under aggressive leaching conditions.
Migration Behavior of Plutonium in Compacted Bentonite Under Reducing Condition Using Electromigration
Authors: Idemitsu Kazuya , Yamasaki Yosuke , Nessa Syeda Afsarun , Inagaki Yaohiro , Arima Tatsumi , Mitsugashira Toshiaki , Hara Mitsuo , Suzuki Yoshimitsu
Published: October 2011

Carbon steel is one of the candidate overpack materials for high-level waste disposal and is expected to assure complete containment of vitrified waste glass during an initial period of 1000 years in Japan. Carbon steel overpack will be corroded by consuming oxygen introduced by repository construction after closure of repository and then will keep the reducing environment in the vicinity of repository. The migration of iron corrosion products through the buffer material will affect migration of redox-sensitive radionuclides. Therefore the authors have carried out electromigration experiments with source of iron ions supplied by anode corrosion of iron coupons attached to compacted bentonite. Authors tried to use plutonium in this experimental configuration to obtain the knowledge of migration behavior of actinides. Authors also used cesium as reference. The concentrations of iron and sodium showed nearly complementary distributions. It is expected that iron ion could migrate as ferrous ion through the interlayer of montmorillonite replacing exchangeable sodium ions in the interlayer. Concentration profiles of plutonium in bentonite grew as time supplying electric potential as long as 168 h. Plutonium migrated from the iron anode toward cathode as deeper than 1 mm of the interior of bentonite even in 48 h, though plutonium could not diffuse 1 mm for 2 years. On the other hand, profiles of cesium seemed to be controlled by ordinary diffusion because of large diffusion coefficient of cesium in bentonite as large as 10$^{-12}$ m$^{2}$/s. Drift of the cesium profile by electric potential gradient could be observed clearly after 240 h at individual experiment for cesium. Apparent dispersion coefficients of plutonium were calculated from the profiles and were as large as 10$^{-13}$ m$^{2}$/s. Since plutonium migration was accelerated by electric potential, plutonium chemical species would have positive charge and were estimated as PuOH$^{2+}$ or PuCl$^{2+}$ by the thermodynamic calculation. Thus this experiment can provide a diffusion field for cations under a reducing condition with ferrous ions in water-saturated bentonite.
Characterizing Low-Permeable Granitic Rock from Micrometer to Centimeter Scale: X-ray Microcomputed Tomography, Confocal Laser Scanning Microscopy and 14C-PMMA Method
Authors: Siitari-Kauppi Marja , Kelokaski M. , Siitari-Kauppi M. , Voutilainen M. , Myllys M. , Turpeinen T. , Timonen J. , Mateos F. , Montoto M.
Published: October 2011

First results of combining X-ray microcomputer tomography (µCT), confocal laser-scanning microscopy (CLSM) and 14C-polymethylmethacrylate (14C-PMMA) impregnation techniques in the study of granitic rock samples are reported. Combining results of µCT and CLSM with those of the 14C-PMMA technique, the mineral-specific porosity and morphology of the open pore space, as well as its connectivity, could be analyzed from a micrometer up to a decimeter scale.

Three different types of granite were studied. In two cases part of the micro-fissure and pore apertures were found to be in a micrometer scale, but in one case all grain-boundary openings were below the detection limit. Micrometer-scale apertures could be analyzed by CLSM and µCT. The benefit of µCT is that it can also provide the heterogeneous distribution of minerals in 3D. The 2D porosity distributions in the mineral phases, consisting of nanometer-scale pores, could be measured by the 14C-PMMA method together with the micro-fissures. This method does not, however, give the exact pore apertures. The limitations and applicability of the methods are discussed.
State of a Bentonite Barrier after 8 Years of Heating and Hydration in the Laboratory
Authors: Villar Maria Victoria , Fernández Ana María , Gómez Roberto , Barrenechea José F. , Luque F. Javier , Martín Pedro Luis , Barcala José Miguel
Published: October 2011

The conditions of the bentonite in an engineered barrier for HLW disposal have been simulated in a laboratory test. Six cylindrical blocks of bentonite compacted at a dry density of 1.64 g/cm3 were piled up in a hermetic Teflon cell. The total length of clay inside the cell was 60 cm. The bottom surface of the bentonite was heated at 100°C while the top surface was injected with granitic water. The duration of the test was 7.6 years. The water intake was measured during the test and, at the end, the cell was dismounted and the dry density, water content, specific surface area, mineralogy, geochemistry and swelling capacity of the clay were measured in different sections along the blocks. The material used in this test is the FEBEX bentonite.
Experimental Approach to Study the Colloid Generation from the Bentonite Barrier to Quantify the Source Term and to Assess its Relevance on the Radionuclide Migration
Authors: Alonso Ursula , Missana Tiziana , García-Gutiérrez Miguel
Published: October 2011

A geological repository for high-level radioactive waste (HLWR) consists on a multi-barrier system, emplaced hundred meters deep in a geological medium. In most of the repository concepts, the waste would be located in metal canisters surrounded by a layer of compacted clay, i.e. bentonite. To guarantee the long-term safety of a repository, all mechanisms that could affect the radionuclide (RN) migration rate must be well defined and quantified. The particular interest of this work lies on the possible contribution of bentonite colloids to RN transport. The first parameter necessary to assess the colloid-mediated transport is the quantification of the bentonite colloid source term. Secondly, it is necessary to define if colloids remain stable in the geochemical conditions of the medium.

Several mechanisms that are basically related to the hydration of the clay can lead to bentonite colloid generation. In the present work the colloid generation is evaluated at laboratory scale under “realistic” conditions, considering static hydration (no flow). To do so, two experimental set-ups were designed with the aim of quantifying the bentonite colloid generation rates. The experimental cells were designed to study the colloid formation in a confined system by introducing compacted bentonite, at different compactation densities, in stainless steel porous filters. The bentonite hydration is facilitated by immersing the confined cells in different electrolytes, from the most favorable conditions (lowest ionic strength) to different groundwaters of interest as aqueous phase. The concentration of bentonite colloids and the average particle size are evaluated as function of time by Photon Correlation Spectroscopy measurements in the aqueous phase.

Preliminary results showed that all the bentonite particles generated have average size in the colloid range, equivalent to that of bentonite colloids prepared in the laboratory, despite the filter porous sizes were hundred times higher. The experimental set up allows performing stability evaluation at the same time and that after months the colloids generated in the lower strength electrolytes remain stable. The configuration allows quantification of the colloid generation rates. The mechanisms responsible of colloid generation are discussed according to the obtained results in different experimental conditions.
Hydrothermal Synthesis and Structure of Neptunium(V) Oxide
Authors: Forbes Tori Z. , Burns Peter C. , Soderholm L. , Skanthakumar S.
Published: October 2011

Single crystals of Np2O5 have been synthesized by low-temperature hydrothermal reaction of a Np5+ stock solution with natural calcite crystals. The structure of Np2O5 was solved by direct methods and refined on the basis of F2 for all unique data collected on a Bruker X-ray diffractometer equipped with an APEX II CCD detector. Np2O5 is monoclinic, space group P2/c, with a = 8.168(2) Å, b = 6.584(1) Å, c = 9.3130(2) Å, β = 116.01(1)˚, V = 449.8(2) Å3, and Z = 1. The structure contains chains of edge-sharing neptunyl pentagonal bipyramids linked into sheets through cation-cation interactions with distorted neptunyl square bipyramids. Additional cation-cation interactions connect the sheets into a three-dimensional framework. The formation of Np2O5 on the surface of calcite crystals has important implications for the precipitation of isolated neptunyl phases in natural aqueous systems.
New Synthesis Route and Characterization of Siderite (FeCO3) and Coprecipitation of 99Tc
Authors: Llorens Isabelle , Fattahi Massoud , Grambow Bernd
Published: October 2011

Technetium-99 is a long-lived product of nuclear fission. In the ground-waters of European disposal sites Tc is expected to be in the tetravalent state since the geochemical conditions are reducing due to the presence of redox couples such as Fe(II)/Fe(III), and the presence of reducing minerals such as pyrite and siderite (FeCO3). Siderite is expected to be formed as well as container corrosion product. Experiments of coprecipitation of Fe2+ and Tc(IV) were conducted in the laboratory under an inert atmosphere at room temperature. High resolution transmission electron microscopy shows that the coprecipitate is around 3 nm sized particles. Analytical electron microscopy indicates that the precipitate contains 30 atom % of Tc and 70 atom % Fe. The Tc was homogeneously distributed. Selected Area Electron Diffraction doesn't reveal the formation of siderite, which suggests that the presence of technetium in high concentration inhibit the formation of this phase.
The geological research in France - The Dosssier 2005 Argile
Authors: Plas Frederic , WENDLING Jacques
Published: October 2011

At the end of fifteen years of researchs defined by the French act of December 30, 1991 on radwaste management, Andra gave a report, “Dossier Argile 2005”, which concluded with the feasibility of a reversible disposal in the argillaceous Callovo-Oxfordien formation studied by means of an underground research laboratory at Meuse/Haute-Marne site. Starting from source data like the characteristics of the geological medium and the waste inventory, the process followed by Andra to achieve at this conclusion is of type sequential and iterative between concept design, scientific knowledge, in particular that of the phenomenological evolution of the reposiroty and its geological environment from operating period to long term, and Safety assessment. The “Dossier Argile 2005” covers a broad radwaste inventory, ILLW, HLW and Spent Fuel, so that it makes it possible to cover whole of the technological, scientific and safety topics. This article will give an overview of the geological disposal studies in France and draw the main conclusion of the Dossier 2005 Argile. It will be focused on the near field (Engineering components and near field host rock), while considering if necessary its integration within the whole system. After a short description of the concepts (incl. waste inventory and the characteristics of the Meuse/Haute the Marne site) and the functions of the components of repository and geological medium, one will describe successively the broad outline of the phenomenological evolution of repository and the geological medium in near field, by in particular releasing the time scales of processes and uncertainties of knowledge. On this basis, one will indicate the safety scenarios which were considered and the broad outline of performance and dose calculations. Lessons learn from the Dossier 2005 Argile will be discussed and perspective and priority for future will be indicated.
The Effects of Dry Density and Porewater Salinity on the Physical and Microbiological Characteristics of Compacted 100% Bentonite
Authors: Stroes-Gascoyne Simcha , Hamon C.J. , Dixon D.A. , Kohle C.L. , Maak P.
Published: October 2011

This study examined the conditions required to suppress microbial activity in compacted bentonite, such that microbially influenced corrosion (MIC) of copper waste containers, surrounded by compacted bentonite in a future deep geologic repository, would become insignificant. Experiments were carried out to determine the effects of dry density and porewater salinity on swelling pressure, water activity (aw) and the culturable microbial community in compacted bentonite. A dry density ³ 1.6 g/cm3 ensures that aw is < 0.96 and the swelling pressure > 2 MPa. Both conditions suppress microbial culturability below background levels (2.1 x 102 Colony-Forming Units/g) in as-purchased bentonite. Under such conditions, cells likely survive as dormant cells or inactive spores, which greatly reduces the possibility of significant MIC. Observations in natural clay-rich environments support these findings.
Measurements of Eh and pH in Compacted MX-80 Bentonite
Authors: Carlsson Torbjörn , Muurinen Arto
Published: October 2011

The low-content free water and high swelling pressure in compacted bentonite, planned to be used as a buffer in nuclear waste repositories, create adverse conditions for direct measurements of the chemical conditions. This paper presents laboratory results from online measurements with Eh and pH electrodes in water-saturated compacted MX-80 bentonite. The Eh was measured with Au and Pt wires as electrodes, while the pH was determined with IrOx electrodes. The latter were prepared in accordance with the method by Yao et al. [1]. The measurements were carried out in two types of cells: 'squeezing cells' and 'diffusion cells'. The squeezing cell excludes almost completely all chemical interactions between the sample and the surrounding environment outside the cell. The diffusion cell, on the other hand, contains a sample that stays in contact with an external solution and therefore allows following of the physico-chemical interaction between the sample and the external solution. The measuring electrodes were positioned inside the cell in the compacted bentonite, while the reference electrode was positioned outside the cell.
Juventude, trabalho e escola: elementos para análise de uma posição social fecunda
Authors: Peregrino Mônica
Published: October 2011

No quadro da retração estrutural do número de postos de trabalho e da expansão da escolarização, a juventude emerge como um problema social. A extensão do tempo de convivência entre trabalho e escola é uma das bases da questão. No Brasil, o problema entra em cena a partir da década de 1990 com contornos próprios: aqui é a expansão da escola que permite a convivência desta instituição para com aquela que se apresentava, até então como umas das mais importantes instituições de socialização dos jovens do país: o trabalho. O presente artigo se propõe a analisar a questão, no quadro particular da situação brasileira, a partir de dois movimentos: primeiramente, pela constituição da noção de juventude como posição social e analítica desta sociedade; em segundo lugar, pelo uso da "ferramenta" na análise da importância relativa da escola e do trabalho na transição do jovem para a vida adulta, a partir do estudo do caso particular de conjunto de jovens de periferia do Rio de Janeiro.
Transplante autólogo de condrócitos
Authors: Barreto Ronald Bispo , Pécora José Ricardo , Gobbi Riccardo Gomes , Rezende Márcia Uchôa de , Camanho Gilberto Luis
Published: October 2011

Esta revisão da literatura descreve o processo do transplante autólogo de condrócitos em todas as suas etapas, indicações clínicas, técnica operatória, técnica laboratorial, reabilitação e resultados clínicos. Desde 1994, quando a técnica de ACI foi descrita pela primeira vez, este procedimento foi aprimorado e tornou-se uma das mais importantes alternativas cirúrgicas para o tratamento das lesões condrais do joelho. Nivel de Evidência II, Prospectivo Comparativo.
Biomassa e nutrição mineral de forrageiras cultivadas em solos do semiárido adubados com esterco
Authors: Araújo Eduardo R. , Silva Tácio O. da , Menezes Rômulo S. C. , Fraga Vânia da S. , Sampaio Everardo V. de S. B.
Published: October 2011

A produção de biomassa e as absorções de N, P e K de quatro espécies forrageiras foram comparadas em três solos representativos da região semi-árida da Paraíba, cultivadas sem e com adubação orgânica. As espécies foram jureminha (Desmanthus virgatus), orelha-de-onça (Macroptilium martii), feijão-de-rolinha (Macroptilium lathyroides) e capim buffel (Cenchrus ciliaris); os solos foram Neossolo Flúvico, Neossolo Regolítico e Planossolo Háplico e a adubação foi realizada com esterco bovino (20 Mg ha-1) comparado com a testemunha. A adubação com esterco promoveu grandes incrementos na produção de biomassa e nas acumulações dos nutrientes, em todas as plantas e solos. O esterco parece ter suprido P às plantas em quantidades suficientes mas não de N e K, confirmando que é uma boa fonte do primeiro elemento. O feijão de rolinha e a orelha de onça tiveram as maiores capacidades de acumulação de biomassa, principalmente em resposta à adubação. O capim buffel atinge maiores teores e conteúdos de K na matéria seca que as leguminosas. Não houve correspondência entre a análise dos solos e sua capacidade de suprimento de nutrientes.
Crescimento e nutrição mineral de milho forrageiro em cultivo hidropônico com soro de leite bovino
Authors: Paula Leila de , Rolim Mário M. , Bezerra Neto Egídio , Soares Tales M. , Pedrosa Elvira M. R. , Silva Ênio F. de F. e
Published: October 2011

Realizou-se este trabalho com o objetivo de avaliar a eficiência nutricional da forragem de milho e a utilização do soro de leite bovino em substituição à solução nutritiva no cultivo de forragem hidropônica de milho. O experimento foi conduzido em casa de vegetação em delineamento experimental inteiramente casualizado, com seis tratamentos e cinco repetições, sendo o tratamento controle representado por solução nutritiva convencionalmente empregada nesse tipo de cultivo; os demais tratamentos foram distribuídos em diferentes níveis de diluição (20, 40, 60, 80 e 100%) do soro de leite em água potável. A colheita foi feita 15 dias após a germinação, separando-se a biomassa da parte aérea da biomassa do substrato com as raízes. Determinaram-se a massa fresca e seca, os teores de macronutrientes (N, P, K, Ca, Mg e S) e micronutrientes (Fe, Cu, Zn e Mn), além dos elementos em níveis tóxicos (Na e Cl), tanto da parte aérea como do sistema radicular. O aumento nas concentrações de soro de leite promoveu redução na produtividade da forragem hidropônica, acréscimo nos teores de N, S e Zn, estabilidade no teor de K e redução do Ca e Mg, não apresentando efeito nos teores de P, Fe e Cu, na parte aérea, enquanto nas raízes ocorreu acréscimo nos teores de P, K, Ca, Mg, S e Cu.
Storage of cut Heliconia bihai (L.) cv. Lobster Claw flowers at low temperatures
Authors: Costa Andreza S. , Nogueira Luis C. , Santos Venézio F. dos , Camara Terezinha R. , Loges Vivian , Willadino Lilia
Published: October 2011

The postharvest conservation of cut Heliconia flowers is an important factor to the success of commercialization, especially with regard to exportation. In the present study, the maximal storage time of cut inflorescences of Heliconia bihai cv. Lobster Claw at two different temperatures (12 and 19 °C) was evaluated and compared to laboratory conditions (25 °C, control treatment). Changes in visual quality, fresh weight and bract color (L*, a* and b*) were determined. The visual quality of the inflorescences and fresh weight decreased with time in all treatments. Symptoms of chilling injury were observed on the inflorescences stored at 12 °C for six and eight days. Bract color was not affected by temperature, storage time or the senescence process. The results indicate that a temperature of 12 °C is not recommended for a storage time longer than four days, whereas 19 °C can be used for a storage time of up to eight days for cut inflorescences of H. bihai cv. Lobster Claw.
Ocupação do solo e ilha de calor noturna em avenidas marginais a um córrego urbano
Authors: Rocha Luciani Maria Vieira , Souza Léa Cristina Lucas , Castilho Francisco José Vigeta
Published: October 2011

Este artigo trata da influência da morfologia urbana na temperatura do ar ao longo das avenidas Alberto Andaló e José Munia, em São José do Rio Preto. Quatro pontos dessas avenidas, ambas situadas ao longo do Córrego Canela, foram selecionados como pontos de coleta de dados de temperatura do ar. Os resultados revelaram que há diferenças de temperaturas entre os pontos. Foram utilizados mapas contendo dados cadastrais e morfológicos, tais como levantamento topográfico, uso e ocupação do solo, configuração das quadras e lotes, altura das edificações e cobertura do solo, obtidos da Prefeitura ou por imagem de satélite e observações de campo. A relação dos dados com as características de uso e ocupação do solo demonstrou uma influência significativa da presença de vegetação e permeabilidade do solo na diminuição da temperatura do ar noturna e, consequentemente, minimização das ilhas de calor. Também se verificou que as áreas com maior ocupação com construções e com maior pavimentação nas ruas e quadras perderam menos calor, levando à formação de ilhas de calor noturnas mais intensas.
A programação arquitetônica sob a ótica da ergonomia: um estudo de caso no setor público
Authors: Patterson Claudia Bartolo , Abrahão Júlia Issy
Published: October 2011

A falta de correspondência entre os ambientes construídos e o uso de edifícios destinados ao Judiciário brasileiro sugerem a dificuldade dos arquitetos em atender, em seus projetos, os requisitos qualitativos e quantitativos das necessidades dos servidores e da organização. A associação da abordagem da ergonomia da atividade à programação arquitetônica foi realizada em resposta à demanda de um novo edifício-sede para um órgão judicial. Tendo uma dissertação de mestrado como referência empírica, este artigo pretende definir parâmetros, fundamentados em procedimentos metodológicos, como suporte para o processo de programação. A equipe multidisciplinar envolvida com a investigação facilitou a articulação das diferentes etapas da análise ergonômica do trabalho. A formação de grupos focais possibilitou a coleta dos dados por meio das representações dos servidores das diferentes unidades do órgão. A definição de módulos de áreas, fundamentada nos dados coletados, permitiu que elementos qualitativos fossem incorporados ao dimensionamento do projeto. Observações sistemáticas em um recorte da situação de estudo complementam a validação dos dados. Ressalta-se a importância do tema na expectativa de aproximação dos arquitetos aos edifícios projetados para o setor público, agregando a realidade de trabalho nos ambientes construídos por eles projetados.
Sincronismo de dispositivos para o georreferenciamento de imagens digitais
Authors: Reis Thiago Tiedtke dos , Camargo Paulo de Oliveira , Tommaselli Antonio Maria Garcia
Published: October 2011

Sensores de posição e orientação podem ser adquiridos e integrados com um custo relativamente baixo para aplicações em mapeamento. A utilização de câmaras digitais de pequeno e médio formato em sistemas de aquisição de imagens aéreas, proporciona vantagens sobre sistemas fotogramétricos convencionais, como: redução de custo, dimensões e peso. Este trabalho teve como objetivo a implementação e avaliação de hardware e software para permitir o sincronismo entre receptores GPS e câmaras digitais de modo a fornecer diretamente as coordenadas do centro perspectivo. O sincronismo foi realizado com o uso do sistema operacional Linux, juntamente com o software NTP, responsável por sincronizar o relógio do computador com uma referência de tempo externa. A validação foi realizada comparando-se diretamente os instantes registrados pelo sistema comercial SPAN-CPT e a técnica proposta neste trabalho. Além disto, os Centros Perspectivos (CPs) determinados pelas técnicas implementadas foram usados em experimentos com fototriangulação de um bloco de imagens, possibilitando a análise de discrepâncias nos pontos de verificação. O resultado do sincronismo apresentou discrepâncias da ordem de 0,15 m em relação ao sistema comercial, implicando na determinação das coordenadas dos CPs com qualidade compatível com a aplicação da técnica desenvolvida em projetos de mapeamento.
Modelagem tridimensional de superfícies planas a partir de imagem TOF
Authors: Oliveira Andrey Augusto Alves de , Centeno Jorge Antonio Silva
Published: October 2011

Neste artigo é apresentado um estudo para a modelagem tridimensional de superfícies utilizando imagens obtidas com uma câmara TOF. O sistema utilizado é a câmara PMD CamCube 2.0, que calcula a distância de objetos utilizando o princípio TOF (Time-Of-Flight). Inicialmente, a câmara foi calibrada, o que possibilitou a correção geométrica da imagem a partir de Parâmetros de Orientação Interior (POI). Outro fator que afeta a qualidade dos dados é a presença de ruído em função da iluminação exterior ao sistema, que pode ser controlada variando o tempo de integração na captação da imagem. Posteriormente realizou-se a segmentação da imagem TOF para identificar as superfícies planas do objeto estudado. A solução encontrada utiliza o cálculo dos autovalores locais em superfícies, em pequenas janelas móveis. Com isto, gera-se uma nova imagem com bordas evidenciadas. A nova imagem é segmentada através do algoritmo de deslocamento pela média, com o objetivo de obter superfícies planas do objeto de interesse. Os píxeis da imagem segmentada são então projetados ortogonalmente, gerando uma nuvem de pontos com coordenadas tridimensionais das superfícies. Finalmente, as dimensões do objeto são comparadas com medidas de referência, sendo verificado que a diferença na medida tridimensional obtida é de aproximadamente 2 centímetros.
Orientação de imagens CBERS-2B usando o modelo rigoroso de colinearidade com dados orbitais
Authors: Marcato Junior José , Tommaselli Antonio Maria Garcia , Oliveira Raquel Alves de , Medeiros Nilcilene das Graças , Marcato Vanessa Jordão
Published: October 2011

Atualmente, o imageamento orbital é uma das principais técnicas de coleta de informações geoespaciais. Embora os sistemas orbitais sejam equipados com sensores de orientação direta (GNSS, giroscópios, sensores de estrelas, dentre outros), nem sempre as imagens corrigidas a partir dos dados (efemérides e atitude) provenientes destes sensores apresentam a acurácia requerida para certas aplicações. Uma das alternativas para solucionar este problema é a orientação dessas imagens considerando as informações de órbita (efemérides e atitude) com o uso adicional de pontos de apoio. O objetivo principal deste trabalho consiste em avaliar experimentalmente o modelo de colinearidade com dados orbitais no processo de orientação de imagens CBERS-2B. Este modelo foi implementado no programa TMS (Triangulação MultiSsensor), seguindo a abordagem de triangulação multissensor. Foram realizados experimentos com imagens do nível 1 (com apenas correção radiométrica) coletadas pelos sensores CCD e HRC. Nos casos estudados verificou-se que a utilização das informações de órbita possibilita a orientação de imagens CBERS-2B com um número reduzido de pontos de apoio.
Italian water services reform from 1994 to 2008: decisional rounds and local modes of governance
Authors: Carrozza Chiara
Published: October 2011

Italian water services reform, started in 1994, has been surrounded by a lively debate on water management models; however, the story of the reform is difficult to understand if only those models chosen by local public agencies are considered. This paper provides a general picture of the reform, analyzes the decision-making process and presents a map of local outcomes. The decision-making analysis considers the course of action taken by the actors involved in reform from 1994 to 2008, and summarizes the events into three rounds. The map of the local modes of governance is focused on the relationship between local authorities and utilities, and has been realized through a collection of data from the 91 areas in which the national system has been reorganized, which has allowed the definition of four ideal types of outcome. The analysis shows that the range of solutions is wider (and the boundaries between them more ambiguous) than commonly assumed by the mainstream national debate which appears to overestimate the role of tools and of formal instruments, and, conversely, to underestimate the real and differentiated abilities and power of the actors in the water sector.
Sanitation under challenge: contributions from the social sciences
Authors: van Vliet Bas J. M. , Spaargaren Gert , Oosterveer Peter
Published: October 2011

This paper reviews the contribution the social sciences can make to the challenge of providing access to sustainable sanitation services and infrastructures for billions of people, in both the over- and underdeveloped parts of the world. The paper reviews and discusses three particular social scientific topics relevant for the sanitation challenge: the nature of socio-technical change, the issue of multilevel governance, and the role of the citizen-consumer. It is argued that sanitation is as much a social as it is a technical issue, and that the role of social scientific knowledge needs to be strengthened and given more attention in this context. The key contribution from the social sciences is to be found in its capacity to help widen the narrow, technical definitions of sanitation by including actors and their needs and belief systems, and by highlighting the alternative socio-technical tools and governance arrangements that are instrumental in moving beyond some of the dead-end roads of traditional water engineering and sanitation provision.
Bioremediation of soil polluted with crude oil and its derivatives: Microorganisms, degradation pathways, technologies
Authors: Beskoski Vladimir , Gojgic-Cvijovic Gordana , Milic Jelena , Ilic Mila , Miletic Srdjan , Jovancicevic Branimir , Vrvic-Miroslav M.
Published: October 2011

The contamination of soil and water with petroleum and its products occurs
due to accidental spills during exploitation, transport, processing, storing
and use. In order to control the environmental risks caused by petroleum
products a variety of techniques based on physical, chemical and biological
methods have been used. Biological methods are considered to have a
comparative advantage as cost effective and environmentally friendly
technologies. Bioremediation, defined as the use of biological systems to
destroy and reduce the concentrations of hazardous waste from contaminated
sites, is an evolving technology for the removal and degradation of petroleum
hydrocarbons as well as industrial solvents, phenols and pesticides.
Microorganisms are the main bioremediation agents due to their diverse
metabolic capacities. In order to enhance the rate of pollutant degradation
the technology optimizes the conditions for the growth of microorganisms
present in soil by aeration, nutrient addition and, if necessary, by adding
separately prepared microorganisms cultures. The other factors that influence
the efficiency of process are temperature, humidity, presence of surfactants,
soil pH, mineral composition, content of organic substance of soil as well as
type and concentration of contaminant. This paper presents a review of our ex
situ bioremediation procedures successfully implemented on the industrial
level. This technology was used for treatment of soils contaminated by crude
oil and its derivatives originated from refinery as well as soils polluted
with oil fuel and transformer oil.
Preconcentration and determination of heavy metals in water, sediment and biological samples
Authors: Shirkhanloo Hamid , Mousavi Zavvar , Rouhollahi Ahmad
Published: October 2011

In this study, a simple, sensitive and accurate column preconcentration
method was developed for the determination of Cd, Cu and Pb ions in river
water, urine and sediment samples by flame atomic absorption spectrometry.
The procedure is based on the retention of the analytes on a mixed cellulose
ester membrane (MCEM) column from buffered sample solutions and then their
elution from the column with nitric acid. Several parameters, such as pH of
the sample solution, volume of the sample and eluent and flow rates of the
sample were evaluated. The effects of diverse ions on the preconcentration
were also investigated. The recoveries were >95 %. The developed method was
applied to the determination of trace metal ions in river water, urine and
sediment samples, with satisfactory results. The 3? detection limits for Cu,
Pb and Cd were found to be 2, 3 and 0.2 ?g dm?3, respectively. The presented
procedure was successfully applied for determination of the copper, lead and
cadmium contents in real samples, i.e., river water and biological samples.
Do Debt Constraints Influence Firms' Sensitivity to a Temporary Tax Holiday on Repatriations?
Authors: Albring Susan M. , Mills Lillian F. , Newberry Kaye J.
Published: October 2011

We examine whether U.S. multinationals' private and public debt constraints influence their responses to a temporary reduction in repatriation taxes (tax holiday). Using a sample of 421 U.S. multinationals with permanently reinvested earnings, we find that external debt constraints played an important role in determining their responses to the tax holiday. Specifically, we find that firms subject to fewer financial covenants in their private debt agreements or with greater access to public bond markets repatriated significantly more of their eligible funds. Our results suggest that U.S. multinationals with greater access to external debt markets have more flexibility to time their repatriations around a tax holiday and, as such, they are the primary beneficiaries of any tax savings. It is unlikely that these firms were the intended target of the American Jobs Creation Act (AJCA) 2004, given the stated legislative goals of directing repatriated funds toward financial stabilization and previously unfunded positive return investments.

JEL Classifications: M4; H2; L1.